From 1a68fdb4f6144ffbdeb9959800e2a25f64a33c67 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Tue, 13 Feb 2018 19:27:56 -0500
Subject: [PATCH 1/5] add support for ssh host key checking

Add `host_key` and `bastion_host_key` fields to the ssh communicator
config for strict host key checking.

Both fields expect the contents of an openssh formated public key. This
key can either be the remote host's public key, or the public key of the
CA which signed the remote host certificate.

Support for signed certificates is limited, because the provisioner
usually connects to a remote host by ip address rather than hostname, so
the certificate would need to be signed appropriately. Connecting via
a hostname needs to currently be done through a secondary provisioner,
like one attached to a null_resource.
---
 communicator/ssh/communicator.go |  8 +++--
 communicator/ssh/provisioner.go  | 51 +++++++++++++++++++++++++++-----
 terraform/eval_validate.go       |  2 ++
 3 files changed, 52 insertions(+), 9 deletions(-)

diff --git a/communicator/ssh/communicator.go b/communicator/ssh/communicator.go
index 4ad67aefc..ba0efe482 100644
--- a/communicator/ssh/communicator.go
+++ b/communicator/ssh/communicator.go
@@ -117,11 +117,13 @@ func (c *Communicator) Connect(o terraform.UIOutput) (err error) {
 				"  User: %s\n"+
 				"  Password: %t\n"+
 				"  Private key: %t\n"+
-				"  SSH Agent: %t",
+				"  SSH Agent: %t\n"+
+				"  Checking Host Key: %t",
 			c.connInfo.Host, c.connInfo.User,
 			c.connInfo.Password != "",
 			c.connInfo.PrivateKey != "",
 			c.connInfo.Agent,
+			c.connInfo.HostKey != "",
 		))
 
 		if c.connInfo.BastionHost != "" {
@@ -131,11 +133,13 @@ func (c *Communicator) Connect(o terraform.UIOutput) (err error) {
 					"  User: %s\n"+
 					"  Password: %t\n"+
 					"  Private key: %t\n"+
-					"  SSH Agent: %t",
+					"  SSH Agent: %t\n"+
+					"  Checking Host Key: %t",
 				c.connInfo.BastionHost, c.connInfo.BastionUser,
 				c.connInfo.BastionPassword != "",
 				c.connInfo.BastionPrivateKey != "",
 				c.connInfo.Agent,
+				c.connInfo.BastionHostKey != "",
 			))
 		}
 	}
diff --git a/communicator/ssh/provisioner.go b/communicator/ssh/provisioner.go
index 69923017e..b6cb1b05f 100644
--- a/communicator/ssh/provisioner.go
+++ b/communicator/ssh/provisioner.go
@@ -18,6 +18,7 @@ import (
 	"github.com/xanzy/ssh-agent"
 	"golang.org/x/crypto/ssh"
 	"golang.org/x/crypto/ssh/agent"
+	"golang.org/x/crypto/ssh/knownhosts"
 )
 
 const (
@@ -43,6 +44,7 @@ type connectionInfo struct {
 	Password   string
 	PrivateKey string `mapstructure:"private_key"`
 	Host       string
+	HostKey    string `mapstructure:"host_key"`
 	Port       int
 	Agent      bool
 	Timeout    string
@@ -53,6 +55,7 @@ type connectionInfo struct {
 	BastionPassword   string `mapstructure:"bastion_password"`
 	BastionPrivateKey string `mapstructure:"bastion_private_key"`
 	BastionHost       string `mapstructure:"bastion_host"`
+	BastionHostKey    string `mapstructure:"bastion_host_key"`
 	BastionPort       int    `mapstructure:"bastion_port"`
 
 	AgentIdentity string `mapstructure:"agent_identity"`
@@ -144,34 +147,38 @@ func prepareSSHConfig(connInfo *connectionInfo) (*sshConfig, error) {
 		return nil, err
 	}
 
+	host := fmt.Sprintf("%s:%d", connInfo.Host, connInfo.Port)
+
 	sshConf, err := buildSSHClientConfig(sshClientConfigOpts{
 		user:       connInfo.User,
+		host:       host,
 		privateKey: connInfo.PrivateKey,
 		password:   connInfo.Password,
+		hostKey:    connInfo.HostKey,
 		sshAgent:   sshAgent,
 	})
 	if err != nil {
 		return nil, err
 	}
 
+	connectFunc := ConnectFunc("tcp", host)
+
 	var bastionConf *ssh.ClientConfig
 	if connInfo.BastionHost != "" {
+		bastionHost := fmt.Sprintf("%s:%d", connInfo.BastionHost, connInfo.BastionPort)
+
 		bastionConf, err = buildSSHClientConfig(sshClientConfigOpts{
 			user:       connInfo.BastionUser,
+			host:       bastionHost,
 			privateKey: connInfo.BastionPrivateKey,
 			password:   connInfo.BastionPassword,
+			hostKey:    connInfo.HostKey,
 			sshAgent:   sshAgent,
 		})
 		if err != nil {
 			return nil, err
 		}
-	}
 
-	host := fmt.Sprintf("%s:%d", connInfo.Host, connInfo.Port)
-	connectFunc := ConnectFunc("tcp", host)
-
-	if bastionConf != nil {
-		bastionHost := fmt.Sprintf("%s:%d", connInfo.BastionHost, connInfo.BastionPort)
 		connectFunc = BastionConnectFunc("tcp", bastionHost, bastionConf, "tcp", host)
 	}
 
@@ -188,11 +195,41 @@ type sshClientConfigOpts struct {
 	password   string
 	sshAgent   *sshAgent
 	user       string
+	host       string
+	hostKey    string
 }
 
 func buildSSHClientConfig(opts sshClientConfigOpts) (*ssh.ClientConfig, error) {
+	hkCallback := ssh.InsecureIgnoreHostKey()
+
+	if opts.hostKey != "" {
+		// The knownhosts package only takes paths to files, but terraform
+		// generally wants to handle config data in-memory. Rather than making
+		// the known_hosts file an exception, write out the data to a temporary
+		// file to create the HostKeyCallback.
+		tf, err := ioutil.TempFile("", "tf-known_hosts")
+		if err != nil {
+			return nil, fmt.Errorf("failed to create temp known_hosts file: %s", err)
+		}
+		defer tf.Close()
+		defer os.RemoveAll(tf.Name())
+
+		// we mark this as a CA as well, but the host key fallback will still
+		// use it as a direct match if the remote host doesn't return a
+		// certificate.
+		if _, err := tf.WriteString(fmt.Sprintf("@cert-authority %s %s\n", opts.host, opts.hostKey)); err != nil {
+			return nil, fmt.Errorf("failed to write temp known_hosts file: %s", err)
+		}
+		tf.Sync()
+
+		hkCallback, err = knownhosts.New(tf.Name())
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	conf := &ssh.ClientConfig{
-		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+		HostKeyCallback: hkCallback,
 		User:            opts.user,
 	}
 
diff --git a/terraform/eval_validate.go b/terraform/eval_validate.go
index e48af84ac..16bca3587 100644
--- a/terraform/eval_validate.go
+++ b/terraform/eval_validate.go
@@ -144,8 +144,10 @@ func (n *EvalValidateProvisioner) validateConnConfig(connConfig *ResourceConfig)
 
 		// For type=ssh only (enforced in ssh communicator)
 		PrivateKey        interface{} `mapstructure:"private_key"`
+		HostKey           interface{} `mapstructure:"host_key"`
 		Agent             interface{} `mapstructure:"agent"`
 		BastionHost       interface{} `mapstructure:"bastion_host"`
+		BastionHostKey    interface{} `mapstructure:"bastion_host_key"`
 		BastionPort       interface{} `mapstructure:"bastion_port"`
 		BastionUser       interface{} `mapstructure:"bastion_user"`
 		BastionPassword   interface{} `mapstructure:"bastion_password"`

From e3e6104007c57a11533a8effa8f66d34721d9cb1 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Tue, 13 Feb 2018 19:28:10 -0500
Subject: [PATCH 2/5] update x/crypt/ssh and add knownhosts package

---
 .../internal/chacha20/chacha_generic.go       | 198 +++++++
 .../golang.org/x/crypto/poly1305/poly1305.go  |  33 ++
 .../golang.org/x/crypto/poly1305/sum_amd64.go |  22 +
 .../golang.org/x/crypto/poly1305/sum_amd64.s  | 125 ++++
 .../golang.org/x/crypto/poly1305/sum_arm.go   |  22 +
 vendor/golang.org/x/crypto/poly1305/sum_arm.s | 427 ++++++++++++++
 .../golang.org/x/crypto/poly1305/sum_ref.go   | 141 +++++
 vendor/golang.org/x/crypto/ssh/certs.go       |   6 +-
 vendor/golang.org/x/crypto/ssh/cipher.go      | 244 ++++++--
 vendor/golang.org/x/crypto/ssh/client_auth.go |  95 +--
 vendor/golang.org/x/crypto/ssh/common.go      |  16 +-
 .../x/crypto/ssh/knownhosts/knownhosts.go     | 546 ++++++++++++++++++
 vendor/golang.org/x/crypto/ssh/transport.go   |  58 +-
 vendor/vendor.json                            |  26 +-
 14 files changed, 1820 insertions(+), 139 deletions(-)
 create mode 100644 vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go
 create mode 100644 vendor/golang.org/x/crypto/poly1305/poly1305.go
 create mode 100644 vendor/golang.org/x/crypto/poly1305/sum_amd64.go
 create mode 100644 vendor/golang.org/x/crypto/poly1305/sum_amd64.s
 create mode 100644 vendor/golang.org/x/crypto/poly1305/sum_arm.go
 create mode 100644 vendor/golang.org/x/crypto/poly1305/sum_arm.s
 create mode 100644 vendor/golang.org/x/crypto/poly1305/sum_ref.go
 create mode 100644 vendor/golang.org/x/crypto/ssh/knownhosts/knownhosts.go

diff --git a/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go b/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go
new file mode 100644
index 000000000..0f8efdbaa
--- /dev/null
+++ b/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go
@@ -0,0 +1,198 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ChaCha20 implements the core ChaCha20 function as specified in https://tools.ietf.org/html/rfc7539#section-2.3.
+package chacha20
+
+import "encoding/binary"
+
+const rounds = 20
+
+// core applies the ChaCha20 core function to 16-byte input in, 32-byte key k,
+// and 16-byte constant c, and puts the result into 64-byte array out.
+func core(out *[64]byte, in *[16]byte, k *[32]byte) {
+	j0 := uint32(0x61707865)
+	j1 := uint32(0x3320646e)
+	j2 := uint32(0x79622d32)
+	j3 := uint32(0x6b206574)
+	j4 := binary.LittleEndian.Uint32(k[0:4])
+	j5 := binary.LittleEndian.Uint32(k[4:8])
+	j6 := binary.LittleEndian.Uint32(k[8:12])
+	j7 := binary.LittleEndian.Uint32(k[12:16])
+	j8 := binary.LittleEndian.Uint32(k[16:20])
+	j9 := binary.LittleEndian.Uint32(k[20:24])
+	j10 := binary.LittleEndian.Uint32(k[24:28])
+	j11 := binary.LittleEndian.Uint32(k[28:32])
+	j12 := binary.LittleEndian.Uint32(in[0:4])
+	j13 := binary.LittleEndian.Uint32(in[4:8])
+	j14 := binary.LittleEndian.Uint32(in[8:12])
+	j15 := binary.LittleEndian.Uint32(in[12:16])
+
+	x0, x1, x2, x3, x4, x5, x6, x7 := j0, j1, j2, j3, j4, j5, j6, j7
+	x8, x9, x10, x11, x12, x13, x14, x15 := j8, j9, j10, j11, j12, j13, j14, j15
+
+	for i := 0; i < rounds; i += 2 {
+		x0 += x4
+		x12 ^= x0
+		x12 = (x12 << 16) | (x12 >> (16))
+		x8 += x12
+		x4 ^= x8
+		x4 = (x4 << 12) | (x4 >> (20))
+		x0 += x4
+		x12 ^= x0
+		x12 = (x12 << 8) | (x12 >> (24))
+		x8 += x12
+		x4 ^= x8
+		x4 = (x4 << 7) | (x4 >> (25))
+		x1 += x5
+		x13 ^= x1
+		x13 = (x13 << 16) | (x13 >> 16)
+		x9 += x13
+		x5 ^= x9
+		x5 = (x5 << 12) | (x5 >> 20)
+		x1 += x5
+		x13 ^= x1
+		x13 = (x13 << 8) | (x13 >> 24)
+		x9 += x13
+		x5 ^= x9
+		x5 = (x5 << 7) | (x5 >> 25)
+		x2 += x6
+		x14 ^= x2
+		x14 = (x14 << 16) | (x14 >> 16)
+		x10 += x14
+		x6 ^= x10
+		x6 = (x6 << 12) | (x6 >> 20)
+		x2 += x6
+		x14 ^= x2
+		x14 = (x14 << 8) | (x14 >> 24)
+		x10 += x14
+		x6 ^= x10
+		x6 = (x6 << 7) | (x6 >> 25)
+		x3 += x7
+		x15 ^= x3
+		x15 = (x15 << 16) | (x15 >> 16)
+		x11 += x15
+		x7 ^= x11
+		x7 = (x7 << 12) | (x7 >> 20)
+		x3 += x7
+		x15 ^= x3
+		x15 = (x15 << 8) | (x15 >> 24)
+		x11 += x15
+		x7 ^= x11
+		x7 = (x7 << 7) | (x7 >> 25)
+		x0 += x5
+		x15 ^= x0
+		x15 = (x15 << 16) | (x15 >> 16)
+		x10 += x15
+		x5 ^= x10
+		x5 = (x5 << 12) | (x5 >> 20)
+		x0 += x5
+		x15 ^= x0
+		x15 = (x15 << 8) | (x15 >> 24)
+		x10 += x15
+		x5 ^= x10
+		x5 = (x5 << 7) | (x5 >> 25)
+		x1 += x6
+		x12 ^= x1
+		x12 = (x12 << 16) | (x12 >> 16)
+		x11 += x12
+		x6 ^= x11
+		x6 = (x6 << 12) | (x6 >> 20)
+		x1 += x6
+		x12 ^= x1
+		x12 = (x12 << 8) | (x12 >> 24)
+		x11 += x12
+		x6 ^= x11
+		x6 = (x6 << 7) | (x6 >> 25)
+		x2 += x7
+		x13 ^= x2
+		x13 = (x13 << 16) | (x13 >> 16)
+		x8 += x13
+		x7 ^= x8
+		x7 = (x7 << 12) | (x7 >> 20)
+		x2 += x7
+		x13 ^= x2
+		x13 = (x13 << 8) | (x13 >> 24)
+		x8 += x13
+		x7 ^= x8
+		x7 = (x7 << 7) | (x7 >> 25)
+		x3 += x4
+		x14 ^= x3
+		x14 = (x14 << 16) | (x14 >> 16)
+		x9 += x14
+		x4 ^= x9
+		x4 = (x4 << 12) | (x4 >> 20)
+		x3 += x4
+		x14 ^= x3
+		x14 = (x14 << 8) | (x14 >> 24)
+		x9 += x14
+		x4 ^= x9
+		x4 = (x4 << 7) | (x4 >> 25)
+	}
+
+	x0 += j0
+	x1 += j1
+	x2 += j2
+	x3 += j3
+	x4 += j4
+	x5 += j5
+	x6 += j6
+	x7 += j7
+	x8 += j8
+	x9 += j9
+	x10 += j10
+	x11 += j11
+	x12 += j12
+	x13 += j13
+	x14 += j14
+	x15 += j15
+
+	binary.LittleEndian.PutUint32(out[0:4], x0)
+	binary.LittleEndian.PutUint32(out[4:8], x1)
+	binary.LittleEndian.PutUint32(out[8:12], x2)
+	binary.LittleEndian.PutUint32(out[12:16], x3)
+	binary.LittleEndian.PutUint32(out[16:20], x4)
+	binary.LittleEndian.PutUint32(out[20:24], x5)
+	binary.LittleEndian.PutUint32(out[24:28], x6)
+	binary.LittleEndian.PutUint32(out[28:32], x7)
+	binary.LittleEndian.PutUint32(out[32:36], x8)
+	binary.LittleEndian.PutUint32(out[36:40], x9)
+	binary.LittleEndian.PutUint32(out[40:44], x10)
+	binary.LittleEndian.PutUint32(out[44:48], x11)
+	binary.LittleEndian.PutUint32(out[48:52], x12)
+	binary.LittleEndian.PutUint32(out[52:56], x13)
+	binary.LittleEndian.PutUint32(out[56:60], x14)
+	binary.LittleEndian.PutUint32(out[60:64], x15)
+}
+
+// XORKeyStream crypts bytes from in to out using the given key and counters.
+// In and out must overlap entirely or not at all. Counter contains the raw
+// ChaCha20 counter bytes (i.e. block counter followed by nonce).
+func XORKeyStream(out, in []byte, counter *[16]byte, key *[32]byte) {
+	var block [64]byte
+	var counterCopy [16]byte
+	copy(counterCopy[:], counter[:])
+
+	for len(in) >= 64 {
+		core(&block, &counterCopy, key)
+		for i, x := range block {
+			out[i] = in[i] ^ x
+		}
+		u := uint32(1)
+		for i := 0; i < 4; i++ {
+			u += uint32(counterCopy[i])
+			counterCopy[i] = byte(u)
+			u >>= 8
+		}
+		in = in[64:]
+		out = out[64:]
+	}
+
+	if len(in) > 0 {
+		core(&block, &counterCopy, key)
+		for i, v := range in {
+			out[i] = v ^ block[i]
+		}
+	}
+}
diff --git a/vendor/golang.org/x/crypto/poly1305/poly1305.go b/vendor/golang.org/x/crypto/poly1305/poly1305.go
new file mode 100644
index 000000000..f562fa571
--- /dev/null
+++ b/vendor/golang.org/x/crypto/poly1305/poly1305.go
@@ -0,0 +1,33 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package poly1305 implements Poly1305 one-time message authentication code as
+specified in https://cr.yp.to/mac/poly1305-20050329.pdf.
+
+Poly1305 is a fast, one-time authentication function. It is infeasible for an
+attacker to generate an authenticator for a message without the key. However, a
+key must only be used for a single message. Authenticating two different
+messages with the same key allows an attacker to forge authenticators for other
+messages with the same key.
+
+Poly1305 was originally coupled with AES in order to make Poly1305-AES. AES was
+used with a fixed key in order to generate one-time keys from an nonce.
+However, in this package AES isn't used and the one-time key is specified
+directly.
+*/
+package poly1305 // import "golang.org/x/crypto/poly1305"
+
+import "crypto/subtle"
+
+// TagSize is the size, in bytes, of a poly1305 authenticator.
+const TagSize = 16
+
+// Verify returns true if mac is a valid authenticator for m with the given
+// key.
+func Verify(mac *[16]byte, m []byte, key *[32]byte) bool {
+	var tmp [16]byte
+	Sum(&tmp, m, key)
+	return subtle.ConstantTimeCompare(tmp[:], mac[:]) == 1
+}
diff --git a/vendor/golang.org/x/crypto/poly1305/sum_amd64.go b/vendor/golang.org/x/crypto/poly1305/sum_amd64.go
new file mode 100644
index 000000000..4dd72fe79
--- /dev/null
+++ b/vendor/golang.org/x/crypto/poly1305/sum_amd64.go
@@ -0,0 +1,22 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build amd64,!gccgo,!appengine
+
+package poly1305
+
+// This function is implemented in sum_amd64.s
+//go:noescape
+func poly1305(out *[16]byte, m *byte, mlen uint64, key *[32]byte)
+
+// Sum generates an authenticator for m using a one-time key and puts the
+// 16-byte result into out. Authenticating two different messages with the same
+// key allows an attacker to forge messages at will.
+func Sum(out *[16]byte, m []byte, key *[32]byte) {
+	var mPtr *byte
+	if len(m) > 0 {
+		mPtr = &m[0]
+	}
+	poly1305(out, mPtr, uint64(len(m)), key)
+}
diff --git a/vendor/golang.org/x/crypto/poly1305/sum_amd64.s b/vendor/golang.org/x/crypto/poly1305/sum_amd64.s
new file mode 100644
index 000000000..2edae6382
--- /dev/null
+++ b/vendor/golang.org/x/crypto/poly1305/sum_amd64.s
@@ -0,0 +1,125 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build amd64,!gccgo,!appengine
+
+#include "textflag.h"
+
+#define POLY1305_ADD(msg, h0, h1, h2) \
+	ADDQ 0(msg), h0;  \
+	ADCQ 8(msg), h1;  \
+	ADCQ $1, h2;      \
+	LEAQ 16(msg), msg
+
+#define POLY1305_MUL(h0, h1, h2, r0, r1, t0, t1, t2, t3) \
+	MOVQ  r0, AX;                  \
+	MULQ  h0;                      \
+	MOVQ  AX, t0;                  \
+	MOVQ  DX, t1;                  \
+	MOVQ  r0, AX;                  \
+	MULQ  h1;                      \
+	ADDQ  AX, t1;                  \
+	ADCQ  $0, DX;                  \
+	MOVQ  r0, t2;                  \
+	IMULQ h2, t2;                  \
+	ADDQ  DX, t2;                  \
+	                               \
+	MOVQ  r1, AX;                  \
+	MULQ  h0;                      \
+	ADDQ  AX, t1;                  \
+	ADCQ  $0, DX;                  \
+	MOVQ  DX, h0;                  \
+	MOVQ  r1, t3;                  \
+	IMULQ h2, t3;                  \
+	MOVQ  r1, AX;                  \
+	MULQ  h1;                      \
+	ADDQ  AX, t2;                  \
+	ADCQ  DX, t3;                  \
+	ADDQ  h0, t2;                  \
+	ADCQ  $0, t3;                  \
+	                               \
+	MOVQ  t0, h0;                  \
+	MOVQ  t1, h1;                  \
+	MOVQ  t2, h2;                  \
+	ANDQ  $3, h2;                  \
+	MOVQ  t2, t0;                  \
+	ANDQ  $0xFFFFFFFFFFFFFFFC, t0; \
+	ADDQ  t0, h0;                  \
+	ADCQ  t3, h1;                  \
+	ADCQ  $0, h2;                  \
+	SHRQ  $2, t3, t2;              \
+	SHRQ  $2, t3;                  \
+	ADDQ  t2, h0;                  \
+	ADCQ  t3, h1;                  \
+	ADCQ  $0, h2
+
+DATA ·poly1305Mask<>+0x00(SB)/8, $0x0FFFFFFC0FFFFFFF
+DATA ·poly1305Mask<>+0x08(SB)/8, $0x0FFFFFFC0FFFFFFC
+GLOBL ·poly1305Mask<>(SB), RODATA, $16
+
+// func poly1305(out *[16]byte, m *byte, mlen uint64, key *[32]key)
+TEXT ·poly1305(SB), $0-32
+	MOVQ out+0(FP), DI
+	MOVQ m+8(FP), SI
+	MOVQ mlen+16(FP), R15
+	MOVQ key+24(FP), AX
+
+	MOVQ 0(AX), R11
+	MOVQ 8(AX), R12
+	ANDQ ·poly1305Mask<>(SB), R11   // r0
+	ANDQ ·poly1305Mask<>+8(SB), R12 // r1
+	XORQ R8, R8                    // h0
+	XORQ R9, R9                    // h1
+	XORQ R10, R10                  // h2
+
+	CMPQ R15, $16
+	JB   bytes_between_0_and_15
+
+loop:
+	POLY1305_ADD(SI, R8, R9, R10)
+
+multiply:
+	POLY1305_MUL(R8, R9, R10, R11, R12, BX, CX, R13, R14)
+	SUBQ $16, R15
+	CMPQ R15, $16
+	JAE  loop
+
+bytes_between_0_and_15:
+	TESTQ R15, R15
+	JZ    done
+	MOVQ  $1, BX
+	XORQ  CX, CX
+	XORQ  R13, R13
+	ADDQ  R15, SI
+
+flush_buffer:
+	SHLQ $8, BX, CX
+	SHLQ $8, BX
+	MOVB -1(SI), R13
+	XORQ R13, BX
+	DECQ SI
+	DECQ R15
+	JNZ  flush_buffer
+
+	ADDQ BX, R8
+	ADCQ CX, R9
+	ADCQ $0, R10
+	MOVQ $16, R15
+	JMP  multiply
+
+done:
+	MOVQ    R8, AX
+	MOVQ    R9, BX
+	SUBQ    $0xFFFFFFFFFFFFFFFB, AX
+	SBBQ    $0xFFFFFFFFFFFFFFFF, BX
+	SBBQ    $3, R10
+	CMOVQCS R8, AX
+	CMOVQCS R9, BX
+	MOVQ    key+24(FP), R8
+	ADDQ    16(R8), AX
+	ADCQ    24(R8), BX
+
+	MOVQ AX, 0(DI)
+	MOVQ BX, 8(DI)
+	RET
diff --git a/vendor/golang.org/x/crypto/poly1305/sum_arm.go b/vendor/golang.org/x/crypto/poly1305/sum_arm.go
new file mode 100644
index 000000000..5dc321c2f
--- /dev/null
+++ b/vendor/golang.org/x/crypto/poly1305/sum_arm.go
@@ -0,0 +1,22 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build arm,!gccgo,!appengine,!nacl
+
+package poly1305
+
+// This function is implemented in sum_arm.s
+//go:noescape
+func poly1305_auth_armv6(out *[16]byte, m *byte, mlen uint32, key *[32]byte)
+
+// Sum generates an authenticator for m using a one-time key and puts the
+// 16-byte result into out. Authenticating two different messages with the same
+// key allows an attacker to forge messages at will.
+func Sum(out *[16]byte, m []byte, key *[32]byte) {
+	var mPtr *byte
+	if len(m) > 0 {
+		mPtr = &m[0]
+	}
+	poly1305_auth_armv6(out, mPtr, uint32(len(m)), key)
+}
diff --git a/vendor/golang.org/x/crypto/poly1305/sum_arm.s b/vendor/golang.org/x/crypto/poly1305/sum_arm.s
new file mode 100644
index 000000000..f70b4ac48
--- /dev/null
+++ b/vendor/golang.org/x/crypto/poly1305/sum_arm.s
@@ -0,0 +1,427 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build arm,!gccgo,!appengine,!nacl
+
+#include "textflag.h"
+
+// This code was translated into a form compatible with 5a from the public
+// domain source by Andrew Moon: github.com/floodyberry/poly1305-opt/blob/master/app/extensions/poly1305.
+
+DATA ·poly1305_init_constants_armv6<>+0x00(SB)/4, $0x3ffffff
+DATA ·poly1305_init_constants_armv6<>+0x04(SB)/4, $0x3ffff03
+DATA ·poly1305_init_constants_armv6<>+0x08(SB)/4, $0x3ffc0ff
+DATA ·poly1305_init_constants_armv6<>+0x0c(SB)/4, $0x3f03fff
+DATA ·poly1305_init_constants_armv6<>+0x10(SB)/4, $0x00fffff
+GLOBL ·poly1305_init_constants_armv6<>(SB), 8, $20
+
+// Warning: the linker may use R11 to synthesize certain instructions. Please
+// take care and verify that no synthetic instructions use it.
+
+TEXT poly1305_init_ext_armv6<>(SB), NOSPLIT, $0
+	// Needs 16 bytes of stack and 64 bytes of space pointed to by R0.  (It
+	// might look like it's only 60 bytes of space but the final four bytes
+	// will be written by another function.) We need to skip over four
+	// bytes of stack because that's saving the value of 'g'.
+	ADD       $4, R13, R8
+	MOVM.IB   [R4-R7], (R8)
+	MOVM.IA.W (R1), [R2-R5]
+	MOVW      $·poly1305_init_constants_armv6<>(SB), R7
+	MOVW      R2, R8
+	MOVW      R2>>26, R9
+	MOVW      R3>>20, g
+	MOVW      R4>>14, R11
+	MOVW      R5>>8, R12
+	ORR       R3<<6, R9, R9
+	ORR       R4<<12, g, g
+	ORR       R5<<18, R11, R11
+	MOVM.IA   (R7), [R2-R6]
+	AND       R8, R2, R2
+	AND       R9, R3, R3
+	AND       g, R4, R4
+	AND       R11, R5, R5
+	AND       R12, R6, R6
+	MOVM.IA.W [R2-R6], (R0)
+	EOR       R2, R2, R2
+	EOR       R3, R3, R3
+	EOR       R4, R4, R4
+	EOR       R5, R5, R5
+	EOR       R6, R6, R6
+	MOVM.IA.W [R2-R6], (R0)
+	MOVM.IA.W (R1), [R2-R5]
+	MOVM.IA   [R2-R6], (R0)
+	ADD       $20, R13, R0
+	MOVM.DA   (R0), [R4-R7]
+	RET
+
+#define MOVW_UNALIGNED(Rsrc, Rdst, Rtmp, offset) \
+	MOVBU (offset+0)(Rsrc), Rtmp; \
+	MOVBU Rtmp, (offset+0)(Rdst); \
+	MOVBU (offset+1)(Rsrc), Rtmp; \
+	MOVBU Rtmp, (offset+1)(Rdst); \
+	MOVBU (offset+2)(Rsrc), Rtmp; \
+	MOVBU Rtmp, (offset+2)(Rdst); \
+	MOVBU (offset+3)(Rsrc), Rtmp; \
+	MOVBU Rtmp, (offset+3)(Rdst)
+
+TEXT poly1305_blocks_armv6<>(SB), NOSPLIT, $0
+	// Needs 24 bytes of stack for saved registers and then 88 bytes of
+	// scratch space after that. We assume that 24 bytes at (R13) have
+	// already been used: four bytes for the link register saved in the
+	// prelude of poly1305_auth_armv6, four bytes for saving the value of g
+	// in that function and 16 bytes of scratch space used around
+	// poly1305_finish_ext_armv6_skip1.
+	ADD     $24, R13, R12
+	MOVM.IB [R4-R8, R14], (R12)
+	MOVW    R0, 88(R13)
+	MOVW    R1, 92(R13)
+	MOVW    R2, 96(R13)
+	MOVW    R1, R14
+	MOVW    R2, R12
+	MOVW    56(R0), R8
+	WORD    $0xe1180008                // TST R8, R8 not working see issue 5921
+	EOR     R6, R6, R6
+	MOVW.EQ $(1<<24), R6
+	MOVW    R6, 84(R13)
+	ADD     $116, R13, g
+	MOVM.IA (R0), [R0-R9]
+	MOVM.IA [R0-R4], (g)
+	CMP     $16, R12
+	BLO     poly1305_blocks_armv6_done
+
+poly1305_blocks_armv6_mainloop:
+	WORD    $0xe31e0003                            // TST R14, #3 not working see issue 5921
+	BEQ     poly1305_blocks_armv6_mainloop_aligned
+	ADD     $100, R13, g
+	MOVW_UNALIGNED(R14, g, R0, 0)
+	MOVW_UNALIGNED(R14, g, R0, 4)
+	MOVW_UNALIGNED(R14, g, R0, 8)
+	MOVW_UNALIGNED(R14, g, R0, 12)
+	MOVM.IA (g), [R0-R3]
+	ADD     $16, R14
+	B       poly1305_blocks_armv6_mainloop_loaded
+
+poly1305_blocks_armv6_mainloop_aligned:
+	MOVM.IA.W (R14), [R0-R3]
+
+poly1305_blocks_armv6_mainloop_loaded:
+	MOVW    R0>>26, g
+	MOVW    R1>>20, R11
+	MOVW    R2>>14, R12
+	MOVW    R14, 92(R13)
+	MOVW    R3>>8, R4
+	ORR     R1<<6, g, g
+	ORR     R2<<12, R11, R11
+	ORR     R3<<18, R12, R12
+	BIC     $0xfc000000, R0, R0
+	BIC     $0xfc000000, g, g
+	MOVW    84(R13), R3
+	BIC     $0xfc000000, R11, R11
+	BIC     $0xfc000000, R12, R12
+	ADD     R0, R5, R5
+	ADD     g, R6, R6
+	ORR     R3, R4, R4
+	ADD     R11, R7, R7
+	ADD     $116, R13, R14
+	ADD     R12, R8, R8
+	ADD     R4, R9, R9
+	MOVM.IA (R14), [R0-R4]
+	MULLU   R4, R5, (R11, g)
+	MULLU   R3, R5, (R14, R12)
+	MULALU  R3, R6, (R11, g)
+	MULALU  R2, R6, (R14, R12)
+	MULALU  R2, R7, (R11, g)
+	MULALU  R1, R7, (R14, R12)
+	ADD     R4<<2, R4, R4
+	ADD     R3<<2, R3, R3
+	MULALU  R1, R8, (R11, g)
+	MULALU  R0, R8, (R14, R12)
+	MULALU  R0, R9, (R11, g)
+	MULALU  R4, R9, (R14, R12)
+	MOVW    g, 76(R13)
+	MOVW    R11, 80(R13)
+	MOVW    R12, 68(R13)
+	MOVW    R14, 72(R13)
+	MULLU   R2, R5, (R11, g)
+	MULLU   R1, R5, (R14, R12)
+	MULALU  R1, R6, (R11, g)
+	MULALU  R0, R6, (R14, R12)
+	MULALU  R0, R7, (R11, g)
+	MULALU  R4, R7, (R14, R12)
+	ADD     R2<<2, R2, R2
+	ADD     R1<<2, R1, R1
+	MULALU  R4, R8, (R11, g)
+	MULALU  R3, R8, (R14, R12)
+	MULALU  R3, R9, (R11, g)
+	MULALU  R2, R9, (R14, R12)
+	MOVW    g, 60(R13)
+	MOVW    R11, 64(R13)
+	MOVW    R12, 52(R13)
+	MOVW    R14, 56(R13)
+	MULLU   R0, R5, (R11, g)
+	MULALU  R4, R6, (R11, g)
+	MULALU  R3, R7, (R11, g)
+	MULALU  R2, R8, (R11, g)
+	MULALU  R1, R9, (R11, g)
+	ADD     $52, R13, R0
+	MOVM.IA (R0), [R0-R7]
+	MOVW    g>>26, R12
+	MOVW    R4>>26, R14
+	ORR     R11<<6, R12, R12
+	ORR     R5<<6, R14, R14
+	BIC     $0xfc000000, g, g
+	BIC     $0xfc000000, R4, R4
+	ADD.S   R12, R0, R0
+	ADC     $0, R1, R1
+	ADD.S   R14, R6, R6
+	ADC     $0, R7, R7
+	MOVW    R0>>26, R12
+	MOVW    R6>>26, R14
+	ORR     R1<<6, R12, R12
+	ORR     R7<<6, R14, R14
+	BIC     $0xfc000000, R0, R0
+	BIC     $0xfc000000, R6, R6
+	ADD     R14<<2, R14, R14
+	ADD.S   R12, R2, R2
+	ADC     $0, R3, R3
+	ADD     R14, g, g
+	MOVW    R2>>26, R12
+	MOVW    g>>26, R14
+	ORR     R3<<6, R12, R12
+	BIC     $0xfc000000, g, R5
+	BIC     $0xfc000000, R2, R7
+	ADD     R12, R4, R4
+	ADD     R14, R0, R0
+	MOVW    R4>>26, R12
+	BIC     $0xfc000000, R4, R8
+	ADD     R12, R6, R9
+	MOVW    96(R13), R12
+	MOVW    92(R13), R14
+	MOVW    R0, R6
+	CMP     $32, R12
+	SUB     $16, R12, R12
+	MOVW    R12, 96(R13)
+	BHS     poly1305_blocks_armv6_mainloop
+
+poly1305_blocks_armv6_done:
+	MOVW    88(R13), R12
+	MOVW    R5, 20(R12)
+	MOVW    R6, 24(R12)
+	MOVW    R7, 28(R12)
+	MOVW    R8, 32(R12)
+	MOVW    R9, 36(R12)
+	ADD     $48, R13, R0
+	MOVM.DA (R0), [R4-R8, R14]
+	RET
+
+#define MOVHUP_UNALIGNED(Rsrc, Rdst, Rtmp) \
+	MOVBU.P 1(Rsrc), Rtmp; \
+	MOVBU.P Rtmp, 1(Rdst); \
+	MOVBU.P 1(Rsrc), Rtmp; \
+	MOVBU.P Rtmp, 1(Rdst)
+
+#define MOVWP_UNALIGNED(Rsrc, Rdst, Rtmp) \
+	MOVHUP_UNALIGNED(Rsrc, Rdst, Rtmp); \
+	MOVHUP_UNALIGNED(Rsrc, Rdst, Rtmp)
+
+// func poly1305_auth_armv6(out *[16]byte, m *byte, mlen uint32, key *[32]key)
+TEXT ·poly1305_auth_armv6(SB), $196-16
+	// The value 196, just above, is the sum of 64 (the size of the context
+	// structure) and 132 (the amount of stack needed).
+	//
+	// At this point, the stack pointer (R13) has been moved down. It
+	// points to the saved link register and there's 196 bytes of free
+	// space above it.
+	//
+	// The stack for this function looks like:
+	//
+	// +---------------------
+	// |
+	// | 64 bytes of context structure
+	// |
+	// +---------------------
+	// |
+	// | 112 bytes for poly1305_blocks_armv6
+	// |
+	// +---------------------
+	// | 16 bytes of final block, constructed at
+	// | poly1305_finish_ext_armv6_skip8
+	// +---------------------
+	// | four bytes of saved 'g'
+	// +---------------------
+	// | lr, saved by prelude    <- R13 points here
+	// +---------------------
+	MOVW g, 4(R13)
+
+	MOVW out+0(FP), R4
+	MOVW m+4(FP), R5
+	MOVW mlen+8(FP), R6
+	MOVW key+12(FP), R7
+
+	ADD  $136, R13, R0 // 136 = 4 + 4 + 16 + 112
+	MOVW R7, R1
+
+	// poly1305_init_ext_armv6 will write to the stack from R13+4, but
+	// that's ok because none of the other values have been written yet.
+	BL    poly1305_init_ext_armv6<>(SB)
+	BIC.S $15, R6, R2
+	BEQ   poly1305_auth_armv6_noblocks
+	ADD   $136, R13, R0
+	MOVW  R5, R1
+	ADD   R2, R5, R5
+	SUB   R2, R6, R6
+	BL    poly1305_blocks_armv6<>(SB)
+
+poly1305_auth_armv6_noblocks:
+	ADD  $136, R13, R0
+	MOVW R5, R1
+	MOVW R6, R2
+	MOVW R4, R3
+
+	MOVW  R0, R5
+	MOVW  R1, R6
+	MOVW  R2, R7
+	MOVW  R3, R8
+	AND.S R2, R2, R2
+	BEQ   poly1305_finish_ext_armv6_noremaining
+	EOR   R0, R0
+	ADD   $8, R13, R9                           // 8 = offset to 16 byte scratch space
+	MOVW  R0, (R9)
+	MOVW  R0, 4(R9)
+	MOVW  R0, 8(R9)
+	MOVW  R0, 12(R9)
+	WORD  $0xe3110003                           // TST R1, #3 not working see issue 5921
+	BEQ   poly1305_finish_ext_armv6_aligned
+	WORD  $0xe3120008                           // TST R2, #8 not working see issue 5921
+	BEQ   poly1305_finish_ext_armv6_skip8
+	MOVWP_UNALIGNED(R1, R9, g)
+	MOVWP_UNALIGNED(R1, R9, g)
+
+poly1305_finish_ext_armv6_skip8:
+	WORD $0xe3120004                     // TST $4, R2 not working see issue 5921
+	BEQ  poly1305_finish_ext_armv6_skip4
+	MOVWP_UNALIGNED(R1, R9, g)
+
+poly1305_finish_ext_armv6_skip4:
+	WORD $0xe3120002                     // TST $2, R2 not working see issue 5921
+	BEQ  poly1305_finish_ext_armv6_skip2
+	MOVHUP_UNALIGNED(R1, R9, g)
+	B    poly1305_finish_ext_armv6_skip2
+
+poly1305_finish_ext_armv6_aligned:
+	WORD      $0xe3120008                             // TST R2, #8 not working see issue 5921
+	BEQ       poly1305_finish_ext_armv6_skip8_aligned
+	MOVM.IA.W (R1), [g-R11]
+	MOVM.IA.W [g-R11], (R9)
+
+poly1305_finish_ext_armv6_skip8_aligned:
+	WORD   $0xe3120004                             // TST $4, R2 not working see issue 5921
+	BEQ    poly1305_finish_ext_armv6_skip4_aligned
+	MOVW.P 4(R1), g
+	MOVW.P g, 4(R9)
+
+poly1305_finish_ext_armv6_skip4_aligned:
+	WORD    $0xe3120002                     // TST $2, R2 not working see issue 5921
+	BEQ     poly1305_finish_ext_armv6_skip2
+	MOVHU.P 2(R1), g
+	MOVH.P  g, 2(R9)
+
+poly1305_finish_ext_armv6_skip2:
+	WORD    $0xe3120001                     // TST $1, R2 not working see issue 5921
+	BEQ     poly1305_finish_ext_armv6_skip1
+	MOVBU.P 1(R1), g
+	MOVBU.P g, 1(R9)
+
+poly1305_finish_ext_armv6_skip1:
+	MOVW  $1, R11
+	MOVBU R11, 0(R9)
+	MOVW  R11, 56(R5)
+	MOVW  R5, R0
+	ADD   $8, R13, R1
+	MOVW  $16, R2
+	BL    poly1305_blocks_armv6<>(SB)
+
+poly1305_finish_ext_armv6_noremaining:
+	MOVW      20(R5), R0
+	MOVW      24(R5), R1
+	MOVW      28(R5), R2
+	MOVW      32(R5), R3
+	MOVW      36(R5), R4
+	MOVW      R4>>26, R12
+	BIC       $0xfc000000, R4, R4
+	ADD       R12<<2, R12, R12
+	ADD       R12, R0, R0
+	MOVW      R0>>26, R12
+	BIC       $0xfc000000, R0, R0
+	ADD       R12, R1, R1
+	MOVW      R1>>26, R12
+	BIC       $0xfc000000, R1, R1
+	ADD       R12, R2, R2
+	MOVW      R2>>26, R12
+	BIC       $0xfc000000, R2, R2
+	ADD       R12, R3, R3
+	MOVW      R3>>26, R12
+	BIC       $0xfc000000, R3, R3
+	ADD       R12, R4, R4
+	ADD       $5, R0, R6
+	MOVW      R6>>26, R12
+	BIC       $0xfc000000, R6, R6
+	ADD       R12, R1, R7
+	MOVW      R7>>26, R12
+	BIC       $0xfc000000, R7, R7
+	ADD       R12, R2, g
+	MOVW      g>>26, R12
+	BIC       $0xfc000000, g, g
+	ADD       R12, R3, R11
+	MOVW      $-(1<<26), R12
+	ADD       R11>>26, R12, R12
+	BIC       $0xfc000000, R11, R11
+	ADD       R12, R4, R9
+	MOVW      R9>>31, R12
+	SUB       $1, R12
+	AND       R12, R6, R6
+	AND       R12, R7, R7
+	AND       R12, g, g
+	AND       R12, R11, R11
+	AND       R12, R9, R9
+	MVN       R12, R12
+	AND       R12, R0, R0
+	AND       R12, R1, R1
+	AND       R12, R2, R2
+	AND       R12, R3, R3
+	AND       R12, R4, R4
+	ORR       R6, R0, R0
+	ORR       R7, R1, R1
+	ORR       g, R2, R2
+	ORR       R11, R3, R3
+	ORR       R9, R4, R4
+	ORR       R1<<26, R0, R0
+	MOVW      R1>>6, R1
+	ORR       R2<<20, R1, R1
+	MOVW      R2>>12, R2
+	ORR       R3<<14, R2, R2
+	MOVW      R3>>18, R3
+	ORR       R4<<8, R3, R3
+	MOVW      40(R5), R6
+	MOVW      44(R5), R7
+	MOVW      48(R5), g
+	MOVW      52(R5), R11
+	ADD.S     R6, R0, R0
+	ADC.S     R7, R1, R1
+	ADC.S     g, R2, R2
+	ADC.S     R11, R3, R3
+	MOVM.IA   [R0-R3], (R8)
+	MOVW      R5, R12
+	EOR       R0, R0, R0
+	EOR       R1, R1, R1
+	EOR       R2, R2, R2
+	EOR       R3, R3, R3
+	EOR       R4, R4, R4
+	EOR       R5, R5, R5
+	EOR       R6, R6, R6
+	EOR       R7, R7, R7
+	MOVM.IA.W [R0-R7], (R12)
+	MOVM.IA   [R0-R7], (R12)
+	MOVW      4(R13), g
+	RET
diff --git a/vendor/golang.org/x/crypto/poly1305/sum_ref.go b/vendor/golang.org/x/crypto/poly1305/sum_ref.go
new file mode 100644
index 000000000..b2805a5ca
--- /dev/null
+++ b/vendor/golang.org/x/crypto/poly1305/sum_ref.go
@@ -0,0 +1,141 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !amd64,!arm gccgo appengine nacl
+
+package poly1305
+
+import "encoding/binary"
+
+// Sum generates an authenticator for msg using a one-time key and puts the
+// 16-byte result into out. Authenticating two different messages with the same
+// key allows an attacker to forge messages at will.
+func Sum(out *[TagSize]byte, msg []byte, key *[32]byte) {
+	var (
+		h0, h1, h2, h3, h4 uint32 // the hash accumulators
+		r0, r1, r2, r3, r4 uint64 // the r part of the key
+	)
+
+	r0 = uint64(binary.LittleEndian.Uint32(key[0:]) & 0x3ffffff)
+	r1 = uint64((binary.LittleEndian.Uint32(key[3:]) >> 2) & 0x3ffff03)
+	r2 = uint64((binary.LittleEndian.Uint32(key[6:]) >> 4) & 0x3ffc0ff)
+	r3 = uint64((binary.LittleEndian.Uint32(key[9:]) >> 6) & 0x3f03fff)
+	r4 = uint64((binary.LittleEndian.Uint32(key[12:]) >> 8) & 0x00fffff)
+
+	R1, R2, R3, R4 := r1*5, r2*5, r3*5, r4*5
+
+	for len(msg) >= TagSize {
+		// h += msg
+		h0 += binary.LittleEndian.Uint32(msg[0:]) & 0x3ffffff
+		h1 += (binary.LittleEndian.Uint32(msg[3:]) >> 2) & 0x3ffffff
+		h2 += (binary.LittleEndian.Uint32(msg[6:]) >> 4) & 0x3ffffff
+		h3 += (binary.LittleEndian.Uint32(msg[9:]) >> 6) & 0x3ffffff
+		h4 += (binary.LittleEndian.Uint32(msg[12:]) >> 8) | (1 << 24)
+
+		// h *= r
+		d0 := (uint64(h0) * r0) + (uint64(h1) * R4) + (uint64(h2) * R3) + (uint64(h3) * R2) + (uint64(h4) * R1)
+		d1 := (d0 >> 26) + (uint64(h0) * r1) + (uint64(h1) * r0) + (uint64(h2) * R4) + (uint64(h3) * R3) + (uint64(h4) * R2)
+		d2 := (d1 >> 26) + (uint64(h0) * r2) + (uint64(h1) * r1) + (uint64(h2) * r0) + (uint64(h3) * R4) + (uint64(h4) * R3)
+		d3 := (d2 >> 26) + (uint64(h0) * r3) + (uint64(h1) * r2) + (uint64(h2) * r1) + (uint64(h3) * r0) + (uint64(h4) * R4)
+		d4 := (d3 >> 26) + (uint64(h0) * r4) + (uint64(h1) * r3) + (uint64(h2) * r2) + (uint64(h3) * r1) + (uint64(h4) * r0)
+
+		// h %= p
+		h0 = uint32(d0) & 0x3ffffff
+		h1 = uint32(d1) & 0x3ffffff
+		h2 = uint32(d2) & 0x3ffffff
+		h3 = uint32(d3) & 0x3ffffff
+		h4 = uint32(d4) & 0x3ffffff
+
+		h0 += uint32(d4>>26) * 5
+		h1 += h0 >> 26
+		h0 = h0 & 0x3ffffff
+
+		msg = msg[TagSize:]
+	}
+
+	if len(msg) > 0 {
+		var block [TagSize]byte
+		off := copy(block[:], msg)
+		block[off] = 0x01
+
+		// h += msg
+		h0 += binary.LittleEndian.Uint32(block[0:]) & 0x3ffffff
+		h1 += (binary.LittleEndian.Uint32(block[3:]) >> 2) & 0x3ffffff
+		h2 += (binary.LittleEndian.Uint32(block[6:]) >> 4) & 0x3ffffff
+		h3 += (binary.LittleEndian.Uint32(block[9:]) >> 6) & 0x3ffffff
+		h4 += (binary.LittleEndian.Uint32(block[12:]) >> 8)
+
+		// h *= r
+		d0 := (uint64(h0) * r0) + (uint64(h1) * R4) + (uint64(h2) * R3) + (uint64(h3) * R2) + (uint64(h4) * R1)
+		d1 := (d0 >> 26) + (uint64(h0) * r1) + (uint64(h1) * r0) + (uint64(h2) * R4) + (uint64(h3) * R3) + (uint64(h4) * R2)
+		d2 := (d1 >> 26) + (uint64(h0) * r2) + (uint64(h1) * r1) + (uint64(h2) * r0) + (uint64(h3) * R4) + (uint64(h4) * R3)
+		d3 := (d2 >> 26) + (uint64(h0) * r3) + (uint64(h1) * r2) + (uint64(h2) * r1) + (uint64(h3) * r0) + (uint64(h4) * R4)
+		d4 := (d3 >> 26) + (uint64(h0) * r4) + (uint64(h1) * r3) + (uint64(h2) * r2) + (uint64(h3) * r1) + (uint64(h4) * r0)
+
+		// h %= p
+		h0 = uint32(d0) & 0x3ffffff
+		h1 = uint32(d1) & 0x3ffffff
+		h2 = uint32(d2) & 0x3ffffff
+		h3 = uint32(d3) & 0x3ffffff
+		h4 = uint32(d4) & 0x3ffffff
+
+		h0 += uint32(d4>>26) * 5
+		h1 += h0 >> 26
+		h0 = h0 & 0x3ffffff
+	}
+
+	// h %= p reduction
+	h2 += h1 >> 26
+	h1 &= 0x3ffffff
+	h3 += h2 >> 26
+	h2 &= 0x3ffffff
+	h4 += h3 >> 26
+	h3 &= 0x3ffffff
+	h0 += 5 * (h4 >> 26)
+	h4 &= 0x3ffffff
+	h1 += h0 >> 26
+	h0 &= 0x3ffffff
+
+	// h - p
+	t0 := h0 + 5
+	t1 := h1 + (t0 >> 26)
+	t2 := h2 + (t1 >> 26)
+	t3 := h3 + (t2 >> 26)
+	t4 := h4 + (t3 >> 26) - (1 << 26)
+	t0 &= 0x3ffffff
+	t1 &= 0x3ffffff
+	t2 &= 0x3ffffff
+	t3 &= 0x3ffffff
+
+	// select h if h < p else h - p
+	t_mask := (t4 >> 31) - 1
+	h_mask := ^t_mask
+	h0 = (h0 & h_mask) | (t0 & t_mask)
+	h1 = (h1 & h_mask) | (t1 & t_mask)
+	h2 = (h2 & h_mask) | (t2 & t_mask)
+	h3 = (h3 & h_mask) | (t3 & t_mask)
+	h4 = (h4 & h_mask) | (t4 & t_mask)
+
+	// h %= 2^128
+	h0 |= h1 << 26
+	h1 = ((h1 >> 6) | (h2 << 20))
+	h2 = ((h2 >> 12) | (h3 << 14))
+	h3 = ((h3 >> 18) | (h4 << 8))
+
+	// s: the s part of the key
+	// tag = (h + s) % (2^128)
+	t := uint64(h0) + uint64(binary.LittleEndian.Uint32(key[16:]))
+	h0 = uint32(t)
+	t = uint64(h1) + uint64(binary.LittleEndian.Uint32(key[20:])) + (t >> 32)
+	h1 = uint32(t)
+	t = uint64(h2) + uint64(binary.LittleEndian.Uint32(key[24:])) + (t >> 32)
+	h2 = uint32(t)
+	t = uint64(h3) + uint64(binary.LittleEndian.Uint32(key[28:])) + (t >> 32)
+	h3 = uint32(t)
+
+	binary.LittleEndian.PutUint32(out[0:], h0)
+	binary.LittleEndian.PutUint32(out[4:], h1)
+	binary.LittleEndian.PutUint32(out[8:], h2)
+	binary.LittleEndian.PutUint32(out[12:], h3)
+}
diff --git a/vendor/golang.org/x/crypto/ssh/certs.go b/vendor/golang.org/x/crypto/ssh/certs.go
index 5c9fadcee..42106f3f2 100644
--- a/vendor/golang.org/x/crypto/ssh/certs.go
+++ b/vendor/golang.org/x/crypto/ssh/certs.go
@@ -44,7 +44,9 @@ type Signature struct {
 const CertTimeInfinity = 1<<64 - 1
 
 // An Certificate represents an OpenSSH certificate as defined in
-// [PROTOCOL.certkeys]?rev=1.8.
+// [PROTOCOL.certkeys]?rev=1.8. The Certificate type implements the
+// PublicKey interface, so it can be unmarshaled using
+// ParsePublicKey.
 type Certificate struct {
 	Nonce           []byte
 	Key             PublicKey
@@ -340,7 +342,7 @@ func (c *CertChecker) Authenticate(conn ConnMetadata, pubKey PublicKey) (*Permis
 // the signature of the certificate.
 func (c *CertChecker) CheckCert(principal string, cert *Certificate) error {
 	if c.IsRevoked != nil && c.IsRevoked(cert) {
-		return fmt.Errorf("ssh: certicate serial %d revoked", cert.Serial)
+		return fmt.Errorf("ssh: certificate serial %d revoked", cert.Serial)
 	}
 
 	for opt := range cert.CriticalOptions {
diff --git a/vendor/golang.org/x/crypto/ssh/cipher.go b/vendor/golang.org/x/crypto/ssh/cipher.go
index e67c5e0aa..30a49fdf2 100644
--- a/vendor/golang.org/x/crypto/ssh/cipher.go
+++ b/vendor/golang.org/x/crypto/ssh/cipher.go
@@ -16,6 +16,9 @@ import (
 	"hash"
 	"io"
 	"io/ioutil"
+
+	"golang.org/x/crypto/internal/chacha20"
+	"golang.org/x/crypto/poly1305"
 )
 
 const (
@@ -53,78 +56,78 @@ func newRC4(key, iv []byte) (cipher.Stream, error) {
 	return rc4.NewCipher(key)
 }
 
-type streamCipherMode struct {
-	keySize    int
-	ivSize     int
-	skip       int
-	createFunc func(key, iv []byte) (cipher.Stream, error)
+type cipherMode struct {
+	keySize int
+	ivSize  int
+	create  func(key, iv []byte, macKey []byte, algs directionAlgorithms) (packetCipher, error)
 }
 
-func (c *streamCipherMode) createStream(key, iv []byte) (cipher.Stream, error) {
-	if len(key) < c.keySize {
-		panic("ssh: key length too small for cipher")
-	}
-	if len(iv) < c.ivSize {
-		panic("ssh: iv too small for cipher")
-	}
-
-	stream, err := c.createFunc(key[:c.keySize], iv[:c.ivSize])
-	if err != nil {
-		return nil, err
-	}
-
-	var streamDump []byte
-	if c.skip > 0 {
-		streamDump = make([]byte, 512)
-	}
-
-	for remainingToDump := c.skip; remainingToDump > 0; {
-		dumpThisTime := remainingToDump
-		if dumpThisTime > len(streamDump) {
-			dumpThisTime = len(streamDump)
+func streamCipherMode(skip int, createFunc func(key, iv []byte) (cipher.Stream, error)) func(key, iv []byte, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+	return func(key, iv, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+		stream, err := createFunc(key, iv)
+		if err != nil {
+			return nil, err
 		}
-		stream.XORKeyStream(streamDump[:dumpThisTime], streamDump[:dumpThisTime])
-		remainingToDump -= dumpThisTime
-	}
 
-	return stream, nil
+		var streamDump []byte
+		if skip > 0 {
+			streamDump = make([]byte, 512)
+		}
+
+		for remainingToDump := skip; remainingToDump > 0; {
+			dumpThisTime := remainingToDump
+			if dumpThisTime > len(streamDump) {
+				dumpThisTime = len(streamDump)
+			}
+			stream.XORKeyStream(streamDump[:dumpThisTime], streamDump[:dumpThisTime])
+			remainingToDump -= dumpThisTime
+		}
+
+		mac := macModes[algs.MAC].new(macKey)
+		return &streamPacketCipher{
+			mac:       mac,
+			etm:       macModes[algs.MAC].etm,
+			macResult: make([]byte, mac.Size()),
+			cipher:    stream,
+		}, nil
+	}
 }
 
 // cipherModes documents properties of supported ciphers. Ciphers not included
 // are not supported and will not be negotiated, even if explicitly requested in
 // ClientConfig.Crypto.Ciphers.
-var cipherModes = map[string]*streamCipherMode{
+var cipherModes = map[string]*cipherMode{
 	// Ciphers from RFC4344, which introduced many CTR-based ciphers. Algorithms
 	// are defined in the order specified in the RFC.
-	"aes128-ctr": {16, aes.BlockSize, 0, newAESCTR},
-	"aes192-ctr": {24, aes.BlockSize, 0, newAESCTR},
-	"aes256-ctr": {32, aes.BlockSize, 0, newAESCTR},
+	"aes128-ctr": {16, aes.BlockSize, streamCipherMode(0, newAESCTR)},
+	"aes192-ctr": {24, aes.BlockSize, streamCipherMode(0, newAESCTR)},
+	"aes256-ctr": {32, aes.BlockSize, streamCipherMode(0, newAESCTR)},
 
 	// Ciphers from RFC4345, which introduces security-improved arcfour ciphers.
 	// They are defined in the order specified in the RFC.
-	"arcfour128": {16, 0, 1536, newRC4},
-	"arcfour256": {32, 0, 1536, newRC4},
+	"arcfour128": {16, 0, streamCipherMode(1536, newRC4)},
+	"arcfour256": {32, 0, streamCipherMode(1536, newRC4)},
 
 	// Cipher defined in RFC 4253, which describes SSH Transport Layer Protocol.
 	// Note that this cipher is not safe, as stated in RFC 4253: "Arcfour (and
 	// RC4) has problems with weak keys, and should be used with caution."
 	// RFC4345 introduces improved versions of Arcfour.
-	"arcfour": {16, 0, 0, newRC4},
+	"arcfour": {16, 0, streamCipherMode(0, newRC4)},
 
-	// AES-GCM is not a stream cipher, so it is constructed with a
-	// special case. If we add any more non-stream ciphers, we
-	// should invest a cleaner way to do this.
-	gcmCipherID: {16, 12, 0, nil},
+	// AEAD ciphers
+	gcmCipherID:        {16, 12, newGCMCipher},
+	chacha20Poly1305ID: {64, 0, newChaCha20Cipher},
 
 	// CBC mode is insecure and so is not included in the default config.
 	// (See http://www.isg.rhul.ac.uk/~kp/SandPfinal.pdf). If absolutely
 	// needed, it's possible to specify a custom Config to enable it.
 	// You should expect that an active attacker can recover plaintext if
 	// you do.
-	aes128cbcID: {16, aes.BlockSize, 0, nil},
+	aes128cbcID: {16, aes.BlockSize, newAESCBCCipher},
 
-	// 3des-cbc is insecure and is disabled by default.
-	tripledescbcID: {24, des.BlockSize, 0, nil},
+	// 3des-cbc is insecure and is not included in the default
+	// config.
+	tripledescbcID: {24, des.BlockSize, newTripleDESCBCCipher},
 }
 
 // prefixLen is the length of the packet prefix that contains the packet length
@@ -304,7 +307,7 @@ type gcmCipher struct {
 	buf    []byte
 }
 
-func newGCMCipher(iv, key []byte) (packetCipher, error) {
+func newGCMCipher(key, iv, unusedMacKey []byte, unusedAlgs directionAlgorithms) (packetCipher, error) {
 	c, err := aes.NewCipher(key)
 	if err != nil {
 		return nil, err
@@ -422,7 +425,7 @@ type cbcCipher struct {
 	oracleCamouflage uint32
 }
 
-func newCBCCipher(c cipher.Block, iv, key, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+func newCBCCipher(c cipher.Block, key, iv, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
 	cbc := &cbcCipher{
 		mac:        macModes[algs.MAC].new(macKey),
 		decrypter:  cipher.NewCBCDecrypter(c, iv),
@@ -436,13 +439,13 @@ func newCBCCipher(c cipher.Block, iv, key, macKey []byte, algs directionAlgorith
 	return cbc, nil
 }
 
-func newAESCBCCipher(iv, key, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+func newAESCBCCipher(key, iv, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
 	c, err := aes.NewCipher(key)
 	if err != nil {
 		return nil, err
 	}
 
-	cbc, err := newCBCCipher(c, iv, key, macKey, algs)
+	cbc, err := newCBCCipher(c, key, iv, macKey, algs)
 	if err != nil {
 		return nil, err
 	}
@@ -450,13 +453,13 @@ func newAESCBCCipher(iv, key, macKey []byte, algs directionAlgorithms) (packetCi
 	return cbc, nil
 }
 
-func newTripleDESCBCCipher(iv, key, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+func newTripleDESCBCCipher(key, iv, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
 	c, err := des.NewTripleDESCipher(key)
 	if err != nil {
 		return nil, err
 	}
 
-	cbc, err := newCBCCipher(c, iv, key, macKey, algs)
+	cbc, err := newCBCCipher(c, key, iv, macKey, algs)
 	if err != nil {
 		return nil, err
 	}
@@ -627,3 +630,142 @@ func (c *cbcCipher) writePacket(seqNum uint32, w io.Writer, rand io.Reader, pack
 
 	return nil
 }
+
+const chacha20Poly1305ID = "chacha20-poly1305@openssh.com"
+
+// chacha20Poly1305Cipher implements the chacha20-poly1305@openssh.com
+// AEAD, which is described here:
+//
+//   https://tools.ietf.org/html/draft-josefsson-ssh-chacha20-poly1305-openssh-00
+//
+// the methods here also implement padding, which RFC4253 Section 6
+// also requires of stream ciphers.
+type chacha20Poly1305Cipher struct {
+	lengthKey  [32]byte
+	contentKey [32]byte
+	buf        []byte
+}
+
+func newChaCha20Cipher(key, unusedIV, unusedMACKey []byte, unusedAlgs directionAlgorithms) (packetCipher, error) {
+	if len(key) != 64 {
+		panic(len(key))
+	}
+
+	c := &chacha20Poly1305Cipher{
+		buf: make([]byte, 256),
+	}
+
+	copy(c.contentKey[:], key[:32])
+	copy(c.lengthKey[:], key[32:])
+	return c, nil
+}
+
+// The Poly1305 key is obtained by encrypting 32 0-bytes.
+var chacha20PolyKeyInput [32]byte
+
+func (c *chacha20Poly1305Cipher) readPacket(seqNum uint32, r io.Reader) ([]byte, error) {
+	var counter [16]byte
+	binary.BigEndian.PutUint64(counter[8:], uint64(seqNum))
+
+	var polyKey [32]byte
+	chacha20.XORKeyStream(polyKey[:], chacha20PolyKeyInput[:], &counter, &c.contentKey)
+
+	encryptedLength := c.buf[:4]
+	if _, err := io.ReadFull(r, encryptedLength); err != nil {
+		return nil, err
+	}
+
+	var lenBytes [4]byte
+	chacha20.XORKeyStream(lenBytes[:], encryptedLength, &counter, &c.lengthKey)
+
+	length := binary.BigEndian.Uint32(lenBytes[:])
+	if length > maxPacket {
+		return nil, errors.New("ssh: invalid packet length, packet too large")
+	}
+
+	contentEnd := 4 + length
+	packetEnd := contentEnd + poly1305.TagSize
+	if uint32(cap(c.buf)) < packetEnd {
+		c.buf = make([]byte, packetEnd)
+		copy(c.buf[:], encryptedLength)
+	} else {
+		c.buf = c.buf[:packetEnd]
+	}
+
+	if _, err := io.ReadFull(r, c.buf[4:packetEnd]); err != nil {
+		return nil, err
+	}
+
+	var mac [poly1305.TagSize]byte
+	copy(mac[:], c.buf[contentEnd:packetEnd])
+	if !poly1305.Verify(&mac, c.buf[:contentEnd], &polyKey) {
+		return nil, errors.New("ssh: MAC failure")
+	}
+
+	counter[0] = 1
+
+	plain := c.buf[4:contentEnd]
+	chacha20.XORKeyStream(plain, plain, &counter, &c.contentKey)
+
+	padding := plain[0]
+	if padding < 4 {
+		// padding is a byte, so it automatically satisfies
+		// the maximum size, which is 255.
+		return nil, fmt.Errorf("ssh: illegal padding %d", padding)
+	}
+
+	if int(padding)+1 >= len(plain) {
+		return nil, fmt.Errorf("ssh: padding %d too large", padding)
+	}
+
+	plain = plain[1 : len(plain)-int(padding)]
+
+	return plain, nil
+}
+
+func (c *chacha20Poly1305Cipher) writePacket(seqNum uint32, w io.Writer, rand io.Reader, payload []byte) error {
+	var counter [16]byte
+	binary.BigEndian.PutUint64(counter[8:], uint64(seqNum))
+
+	var polyKey [32]byte
+	chacha20.XORKeyStream(polyKey[:], chacha20PolyKeyInput[:], &counter, &c.contentKey)
+
+	// There is no blocksize, so fall back to multiple of 8 byte
+	// padding, as described in RFC 4253, Sec 6.
+	const packetSizeMultiple = 8
+
+	padding := packetSizeMultiple - (1+len(payload))%packetSizeMultiple
+	if padding < 4 {
+		padding += packetSizeMultiple
+	}
+
+	// size (4 bytes), padding (1), payload, padding, tag.
+	totalLength := 4 + 1 + len(payload) + padding + poly1305.TagSize
+	if cap(c.buf) < totalLength {
+		c.buf = make([]byte, totalLength)
+	} else {
+		c.buf = c.buf[:totalLength]
+	}
+
+	binary.BigEndian.PutUint32(c.buf, uint32(1+len(payload)+padding))
+	chacha20.XORKeyStream(c.buf, c.buf[:4], &counter, &c.lengthKey)
+	c.buf[4] = byte(padding)
+	copy(c.buf[5:], payload)
+	packetEnd := 5 + len(payload) + padding
+	if _, err := io.ReadFull(rand, c.buf[5+len(payload):packetEnd]); err != nil {
+		return err
+	}
+
+	counter[0] = 1
+	chacha20.XORKeyStream(c.buf[4:], c.buf[4:packetEnd], &counter, &c.contentKey)
+
+	var mac [poly1305.TagSize]byte
+	poly1305.Sum(&mac, c.buf[:packetEnd], &polyKey)
+
+	copy(c.buf[packetEnd:], mac[:])
+
+	if _, err := w.Write(c.buf); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/vendor/golang.org/x/crypto/ssh/client_auth.go b/vendor/golang.org/x/crypto/ssh/client_auth.go
index a1252cb9b..5f44b7740 100644
--- a/vendor/golang.org/x/crypto/ssh/client_auth.go
+++ b/vendor/golang.org/x/crypto/ssh/client_auth.go
@@ -11,6 +11,14 @@ import (
 	"io"
 )
 
+type authResult int
+
+const (
+	authFailure authResult = iota
+	authPartialSuccess
+	authSuccess
+)
+
 // clientAuthenticate authenticates with the remote server. See RFC 4252.
 func (c *connection) clientAuthenticate(config *ClientConfig) error {
 	// initiate user auth session
@@ -37,11 +45,12 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error {
 		if err != nil {
 			return err
 		}
-		if ok {
+		if ok == authSuccess {
 			// success
 			return nil
+		} else if ok == authFailure {
+			tried[auth.method()] = true
 		}
-		tried[auth.method()] = true
 		if methods == nil {
 			methods = lastMethods
 		}
@@ -82,7 +91,7 @@ type AuthMethod interface {
 	// If authentication is not successful, a []string of alternative
 	// method names is returned. If the slice is nil, it will be ignored
 	// and the previous set of possible methods will be reused.
-	auth(session []byte, user string, p packetConn, rand io.Reader) (bool, []string, error)
+	auth(session []byte, user string, p packetConn, rand io.Reader) (authResult, []string, error)
 
 	// method returns the RFC 4252 method name.
 	method() string
@@ -91,13 +100,13 @@ type AuthMethod interface {
 // "none" authentication, RFC 4252 section 5.2.
 type noneAuth int
 
-func (n *noneAuth) auth(session []byte, user string, c packetConn, rand io.Reader) (bool, []string, error) {
+func (n *noneAuth) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) {
 	if err := c.writePacket(Marshal(&userAuthRequestMsg{
 		User:    user,
 		Service: serviceSSH,
 		Method:  "none",
 	})); err != nil {
-		return false, nil, err
+		return authFailure, nil, err
 	}
 
 	return handleAuthResponse(c)
@@ -111,7 +120,7 @@ func (n *noneAuth) method() string {
 // a function call, e.g. by prompting the user.
 type passwordCallback func() (password string, err error)
 
-func (cb passwordCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (bool, []string, error) {
+func (cb passwordCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) {
 	type passwordAuthMsg struct {
 		User     string `sshtype:"50"`
 		Service  string
@@ -125,7 +134,7 @@ func (cb passwordCallback) auth(session []byte, user string, c packetConn, rand
 	// The program may only find out that the user doesn't have a password
 	// when prompting.
 	if err != nil {
-		return false, nil, err
+		return authFailure, nil, err
 	}
 
 	if err := c.writePacket(Marshal(&passwordAuthMsg{
@@ -135,7 +144,7 @@ func (cb passwordCallback) auth(session []byte, user string, c packetConn, rand
 		Reply:    false,
 		Password: pw,
 	})); err != nil {
-		return false, nil, err
+		return authFailure, nil, err
 	}
 
 	return handleAuthResponse(c)
@@ -178,7 +187,7 @@ func (cb publicKeyCallback) method() string {
 	return "publickey"
 }
 
-func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (bool, []string, error) {
+func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) {
 	// Authentication is performed by sending an enquiry to test if a key is
 	// acceptable to the remote. If the key is acceptable, the client will
 	// attempt to authenticate with the valid key.  If not the client will repeat
@@ -186,13 +195,13 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand
 
 	signers, err := cb()
 	if err != nil {
-		return false, nil, err
+		return authFailure, nil, err
 	}
 	var methods []string
 	for _, signer := range signers {
 		ok, err := validateKey(signer.PublicKey(), user, c)
 		if err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
 		if !ok {
 			continue
@@ -206,7 +215,7 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand
 			Method:  cb.method(),
 		}, []byte(pub.Type()), pubKey))
 		if err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
 
 		// manually wrap the serialized signature in a string
@@ -224,24 +233,24 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand
 		}
 		p := Marshal(&msg)
 		if err := c.writePacket(p); err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
-		var success bool
+		var success authResult
 		success, methods, err = handleAuthResponse(c)
 		if err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
 
 		// If authentication succeeds or the list of available methods does not
 		// contain the "publickey" method, do not attempt to authenticate with any
 		// other keys.  According to RFC 4252 Section 7, the latter can occur when
 		// additional authentication methods are required.
-		if success || !containsMethod(methods, cb.method()) {
+		if success == authSuccess || !containsMethod(methods, cb.method()) {
 			return success, methods, err
 		}
 	}
 
-	return false, methods, nil
+	return authFailure, methods, nil
 }
 
 func containsMethod(methods []string, method string) bool {
@@ -318,28 +327,31 @@ func PublicKeysCallback(getSigners func() (signers []Signer, err error)) AuthMet
 // handleAuthResponse returns whether the preceding authentication request succeeded
 // along with a list of remaining authentication methods to try next and
 // an error if an unexpected response was received.
-func handleAuthResponse(c packetConn) (bool, []string, error) {
+func handleAuthResponse(c packetConn) (authResult, []string, error) {
 	for {
 		packet, err := c.readPacket()
 		if err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
 
 		switch packet[0] {
 		case msgUserAuthBanner:
 			if err := handleBannerResponse(c, packet); err != nil {
-				return false, nil, err
+				return authFailure, nil, err
 			}
 		case msgUserAuthFailure:
 			var msg userAuthFailureMsg
 			if err := Unmarshal(packet, &msg); err != nil {
-				return false, nil, err
+				return authFailure, nil, err
 			}
-			return false, msg.Methods, nil
+			if msg.PartialSuccess {
+				return authPartialSuccess, msg.Methods, nil
+			}
+			return authFailure, msg.Methods, nil
 		case msgUserAuthSuccess:
-			return true, nil, nil
+			return authSuccess, nil, nil
 		default:
-			return false, nil, unexpectedMessageError(msgUserAuthSuccess, packet[0])
+			return authFailure, nil, unexpectedMessageError(msgUserAuthSuccess, packet[0])
 		}
 	}
 }
@@ -381,7 +393,7 @@ func (cb KeyboardInteractiveChallenge) method() string {
 	return "keyboard-interactive"
 }
 
-func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packetConn, rand io.Reader) (bool, []string, error) {
+func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) {
 	type initiateMsg struct {
 		User       string `sshtype:"50"`
 		Service    string
@@ -395,20 +407,20 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
 		Service: serviceSSH,
 		Method:  "keyboard-interactive",
 	})); err != nil {
-		return false, nil, err
+		return authFailure, nil, err
 	}
 
 	for {
 		packet, err := c.readPacket()
 		if err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
 
 		// like handleAuthResponse, but with less options.
 		switch packet[0] {
 		case msgUserAuthBanner:
 			if err := handleBannerResponse(c, packet); err != nil {
-				return false, nil, err
+				return authFailure, nil, err
 			}
 			continue
 		case msgUserAuthInfoRequest:
@@ -416,18 +428,21 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
 		case msgUserAuthFailure:
 			var msg userAuthFailureMsg
 			if err := Unmarshal(packet, &msg); err != nil {
-				return false, nil, err
+				return authFailure, nil, err
 			}
-			return false, msg.Methods, nil
+			if msg.PartialSuccess {
+				return authPartialSuccess, msg.Methods, nil
+			}
+			return authFailure, msg.Methods, nil
 		case msgUserAuthSuccess:
-			return true, nil, nil
+			return authSuccess, nil, nil
 		default:
-			return false, nil, unexpectedMessageError(msgUserAuthInfoRequest, packet[0])
+			return authFailure, nil, unexpectedMessageError(msgUserAuthInfoRequest, packet[0])
 		}
 
 		var msg userAuthInfoRequestMsg
 		if err := Unmarshal(packet, &msg); err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
 
 		// Manually unpack the prompt/echo pairs.
@@ -437,7 +452,7 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
 		for i := 0; i < int(msg.NumPrompts); i++ {
 			prompt, r, ok := parseString(rest)
 			if !ok || len(r) == 0 {
-				return false, nil, errors.New("ssh: prompt format error")
+				return authFailure, nil, errors.New("ssh: prompt format error")
 			}
 			prompts = append(prompts, string(prompt))
 			echos = append(echos, r[0] != 0)
@@ -445,16 +460,16 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
 		}
 
 		if len(rest) != 0 {
-			return false, nil, errors.New("ssh: extra data following keyboard-interactive pairs")
+			return authFailure, nil, errors.New("ssh: extra data following keyboard-interactive pairs")
 		}
 
 		answers, err := cb(msg.User, msg.Instruction, prompts, echos)
 		if err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
 
 		if len(answers) != len(prompts) {
-			return false, nil, errors.New("ssh: not enough answers from keyboard-interactive callback")
+			return authFailure, nil, errors.New("ssh: not enough answers from keyboard-interactive callback")
 		}
 		responseLength := 1 + 4
 		for _, a := range answers {
@@ -470,7 +485,7 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
 		}
 
 		if err := c.writePacket(serialized); err != nil {
-			return false, nil, err
+			return authFailure, nil, err
 		}
 	}
 }
@@ -480,10 +495,10 @@ type retryableAuthMethod struct {
 	maxTries   int
 }
 
-func (r *retryableAuthMethod) auth(session []byte, user string, c packetConn, rand io.Reader) (ok bool, methods []string, err error) {
+func (r *retryableAuthMethod) auth(session []byte, user string, c packetConn, rand io.Reader) (ok authResult, methods []string, err error) {
 	for i := 0; r.maxTries <= 0 || i < r.maxTries; i++ {
 		ok, methods, err = r.authMethod.auth(session, user, c, rand)
-		if ok || err != nil { // either success or error terminate
+		if ok != authFailure || err != nil { // either success, partial success or error terminate
 			return ok, methods, err
 		}
 	}
diff --git a/vendor/golang.org/x/crypto/ssh/common.go b/vendor/golang.org/x/crypto/ssh/common.go
index 135b4edd7..04f3620b3 100644
--- a/vendor/golang.org/x/crypto/ssh/common.go
+++ b/vendor/golang.org/x/crypto/ssh/common.go
@@ -24,11 +24,21 @@ const (
 	serviceSSH      = "ssh-connection"
 )
 
-// supportedCiphers specifies the supported ciphers in preference order.
+// supportedCiphers lists ciphers we support but might not recommend.
 var supportedCiphers = []string{
 	"aes128-ctr", "aes192-ctr", "aes256-ctr",
 	"aes128-gcm@openssh.com",
-	"arcfour256", "arcfour128",
+	chacha20Poly1305ID,
+	"arcfour256", "arcfour128", "arcfour",
+	aes128cbcID,
+	tripledescbcID,
+}
+
+// preferredCiphers specifies the default preference for ciphers.
+var preferredCiphers = []string{
+	"aes128-gcm@openssh.com",
+	chacha20Poly1305ID,
+	"aes128-ctr", "aes192-ctr", "aes256-ctr",
 }
 
 // supportedKexAlgos specifies the supported key-exchange algorithms in
@@ -211,7 +221,7 @@ func (c *Config) SetDefaults() {
 		c.Rand = rand.Reader
 	}
 	if c.Ciphers == nil {
-		c.Ciphers = supportedCiphers
+		c.Ciphers = preferredCiphers
 	}
 	var ciphers []string
 	for _, c := range c.Ciphers {
diff --git a/vendor/golang.org/x/crypto/ssh/knownhosts/knownhosts.go b/vendor/golang.org/x/crypto/ssh/knownhosts/knownhosts.go
new file mode 100644
index 000000000..46dad1401
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/knownhosts/knownhosts.go
@@ -0,0 +1,546 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package knownhosts implements a parser for the OpenSSH
+// known_hosts host key database.
+package knownhosts
+
+import (
+	"bufio"
+	"bytes"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha1"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"strings"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// See the sshd manpage
+// (http://man.openbsd.org/sshd#SSH_KNOWN_HOSTS_FILE_FORMAT) for
+// background.
+
+type addr struct{ host, port string }
+
+func (a *addr) String() string {
+	h := a.host
+	if strings.Contains(h, ":") {
+		h = "[" + h + "]"
+	}
+	return h + ":" + a.port
+}
+
+type matcher interface {
+	match([]addr) bool
+}
+
+type hostPattern struct {
+	negate bool
+	addr   addr
+}
+
+func (p *hostPattern) String() string {
+	n := ""
+	if p.negate {
+		n = "!"
+	}
+
+	return n + p.addr.String()
+}
+
+type hostPatterns []hostPattern
+
+func (ps hostPatterns) match(addrs []addr) bool {
+	matched := false
+	for _, p := range ps {
+		for _, a := range addrs {
+			m := p.match(a)
+			if !m {
+				continue
+			}
+			if p.negate {
+				return false
+			}
+			matched = true
+		}
+	}
+	return matched
+}
+
+// See
+// https://android.googlesource.com/platform/external/openssh/+/ab28f5495c85297e7a597c1ba62e996416da7c7e/addrmatch.c
+// The matching of * has no regard for separators, unlike filesystem globs
+func wildcardMatch(pat []byte, str []byte) bool {
+	for {
+		if len(pat) == 0 {
+			return len(str) == 0
+		}
+		if len(str) == 0 {
+			return false
+		}
+
+		if pat[0] == '*' {
+			if len(pat) == 1 {
+				return true
+			}
+
+			for j := range str {
+				if wildcardMatch(pat[1:], str[j:]) {
+					return true
+				}
+			}
+			return false
+		}
+
+		if pat[0] == '?' || pat[0] == str[0] {
+			pat = pat[1:]
+			str = str[1:]
+		} else {
+			return false
+		}
+	}
+}
+
+func (p *hostPattern) match(a addr) bool {
+	return wildcardMatch([]byte(p.addr.host), []byte(a.host)) && p.addr.port == a.port
+}
+
+type keyDBLine struct {
+	cert     bool
+	matcher  matcher
+	knownKey KnownKey
+}
+
+func serialize(k ssh.PublicKey) string {
+	return k.Type() + " " + base64.StdEncoding.EncodeToString(k.Marshal())
+}
+
+func (l *keyDBLine) match(addrs []addr) bool {
+	return l.matcher.match(addrs)
+}
+
+type hostKeyDB struct {
+	// Serialized version of revoked keys
+	revoked map[string]*KnownKey
+	lines   []keyDBLine
+}
+
+func newHostKeyDB() *hostKeyDB {
+	db := &hostKeyDB{
+		revoked: make(map[string]*KnownKey),
+	}
+
+	return db
+}
+
+func keyEq(a, b ssh.PublicKey) bool {
+	return bytes.Equal(a.Marshal(), b.Marshal())
+}
+
+// IsAuthorityForHost can be used as a callback in ssh.CertChecker
+func (db *hostKeyDB) IsHostAuthority(remote ssh.PublicKey, address string) bool {
+	h, p, err := net.SplitHostPort(address)
+	if err != nil {
+		return false
+	}
+	a := addr{host: h, port: p}
+
+	for _, l := range db.lines {
+		if l.cert && keyEq(l.knownKey.Key, remote) && l.match([]addr{a}) {
+			return true
+		}
+	}
+	return false
+}
+
+// IsRevoked can be used as a callback in ssh.CertChecker
+func (db *hostKeyDB) IsRevoked(key *ssh.Certificate) bool {
+	_, ok := db.revoked[string(key.Marshal())]
+	return ok
+}
+
+const markerCert = "@cert-authority"
+const markerRevoked = "@revoked"
+
+func nextWord(line []byte) (string, []byte) {
+	i := bytes.IndexAny(line, "\t ")
+	if i == -1 {
+		return string(line), nil
+	}
+
+	return string(line[:i]), bytes.TrimSpace(line[i:])
+}
+
+func parseLine(line []byte) (marker, host string, key ssh.PublicKey, err error) {
+	if w, next := nextWord(line); w == markerCert || w == markerRevoked {
+		marker = w
+		line = next
+	}
+
+	host, line = nextWord(line)
+	if len(line) == 0 {
+		return "", "", nil, errors.New("knownhosts: missing host pattern")
+	}
+
+	// ignore the keytype as it's in the key blob anyway.
+	_, line = nextWord(line)
+	if len(line) == 0 {
+		return "", "", nil, errors.New("knownhosts: missing key type pattern")
+	}
+
+	keyBlob, _ := nextWord(line)
+
+	keyBytes, err := base64.StdEncoding.DecodeString(keyBlob)
+	if err != nil {
+		return "", "", nil, err
+	}
+	key, err = ssh.ParsePublicKey(keyBytes)
+	if err != nil {
+		return "", "", nil, err
+	}
+
+	return marker, host, key, nil
+}
+
+func (db *hostKeyDB) parseLine(line []byte, filename string, linenum int) error {
+	marker, pattern, key, err := parseLine(line)
+	if err != nil {
+		return err
+	}
+
+	if marker == markerRevoked {
+		db.revoked[string(key.Marshal())] = &KnownKey{
+			Key:      key,
+			Filename: filename,
+			Line:     linenum,
+		}
+
+		return nil
+	}
+
+	entry := keyDBLine{
+		cert: marker == markerCert,
+		knownKey: KnownKey{
+			Filename: filename,
+			Line:     linenum,
+			Key:      key,
+		},
+	}
+
+	if pattern[0] == '|' {
+		entry.matcher, err = newHashedHost(pattern)
+	} else {
+		entry.matcher, err = newHostnameMatcher(pattern)
+	}
+
+	if err != nil {
+		return err
+	}
+
+	db.lines = append(db.lines, entry)
+	return nil
+}
+
+func newHostnameMatcher(pattern string) (matcher, error) {
+	var hps hostPatterns
+	for _, p := range strings.Split(pattern, ",") {
+		if len(p) == 0 {
+			continue
+		}
+
+		var a addr
+		var negate bool
+		if p[0] == '!' {
+			negate = true
+			p = p[1:]
+		}
+
+		if len(p) == 0 {
+			return nil, errors.New("knownhosts: negation without following hostname")
+		}
+
+		var err error
+		if p[0] == '[' {
+			a.host, a.port, err = net.SplitHostPort(p)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			a.host, a.port, err = net.SplitHostPort(p)
+			if err != nil {
+				a.host = p
+				a.port = "22"
+			}
+		}
+		hps = append(hps, hostPattern{
+			negate: negate,
+			addr:   a,
+		})
+	}
+	return hps, nil
+}
+
+// KnownKey represents a key declared in a known_hosts file.
+type KnownKey struct {
+	Key      ssh.PublicKey
+	Filename string
+	Line     int
+}
+
+func (k *KnownKey) String() string {
+	return fmt.Sprintf("%s:%d: %s", k.Filename, k.Line, serialize(k.Key))
+}
+
+// KeyError is returned if we did not find the key in the host key
+// database, or there was a mismatch.  Typically, in batch
+// applications, this should be interpreted as failure. Interactive
+// applications can offer an interactive prompt to the user.
+type KeyError struct {
+	// Want holds the accepted host keys. For each key algorithm,
+	// there can be one hostkey.  If Want is empty, the host is
+	// unknown. If Want is non-empty, there was a mismatch, which
+	// can signify a MITM attack.
+	Want []KnownKey
+}
+
+func (u *KeyError) Error() string {
+	if len(u.Want) == 0 {
+		return "knownhosts: key is unknown"
+	}
+	return "knownhosts: key mismatch"
+}
+
+// RevokedError is returned if we found a key that was revoked.
+type RevokedError struct {
+	Revoked KnownKey
+}
+
+func (r *RevokedError) Error() string {
+	return "knownhosts: key is revoked"
+}
+
+// check checks a key against the host database. This should not be
+// used for verifying certificates.
+func (db *hostKeyDB) check(address string, remote net.Addr, remoteKey ssh.PublicKey) error {
+	if revoked := db.revoked[string(remoteKey.Marshal())]; revoked != nil {
+		return &RevokedError{Revoked: *revoked}
+	}
+
+	host, port, err := net.SplitHostPort(remote.String())
+	if err != nil {
+		return fmt.Errorf("knownhosts: SplitHostPort(%s): %v", remote, err)
+	}
+
+	addrs := []addr{
+		{host, port},
+	}
+
+	if address != "" {
+		host, port, err := net.SplitHostPort(address)
+		if err != nil {
+			return fmt.Errorf("knownhosts: SplitHostPort(%s): %v", address, err)
+		}
+
+		addrs = append(addrs, addr{host, port})
+	}
+
+	return db.checkAddrs(addrs, remoteKey)
+}
+
+// checkAddrs checks if we can find the given public key for any of
+// the given addresses.  If we only find an entry for the IP address,
+// or only the hostname, then this still succeeds.
+func (db *hostKeyDB) checkAddrs(addrs []addr, remoteKey ssh.PublicKey) error {
+	// TODO(hanwen): are these the right semantics? What if there
+	// is just a key for the IP address, but not for the
+	// hostname?
+
+	// Algorithm => key.
+	knownKeys := map[string]KnownKey{}
+	for _, l := range db.lines {
+		if l.match(addrs) {
+			typ := l.knownKey.Key.Type()
+			if _, ok := knownKeys[typ]; !ok {
+				knownKeys[typ] = l.knownKey
+			}
+		}
+	}
+
+	keyErr := &KeyError{}
+	for _, v := range knownKeys {
+		keyErr.Want = append(keyErr.Want, v)
+	}
+
+	// Unknown remote host.
+	if len(knownKeys) == 0 {
+		return keyErr
+	}
+
+	// If the remote host starts using a different, unknown key type, we
+	// also interpret that as a mismatch.
+	if known, ok := knownKeys[remoteKey.Type()]; !ok || !keyEq(known.Key, remoteKey) {
+		return keyErr
+	}
+
+	return nil
+}
+
+// The Read function parses file contents.
+func (db *hostKeyDB) Read(r io.Reader, filename string) error {
+	scanner := bufio.NewScanner(r)
+
+	lineNum := 0
+	for scanner.Scan() {
+		lineNum++
+		line := scanner.Bytes()
+		line = bytes.TrimSpace(line)
+		if len(line) == 0 || line[0] == '#' {
+			continue
+		}
+
+		if err := db.parseLine(line, filename, lineNum); err != nil {
+			return fmt.Errorf("knownhosts: %s:%d: %v", filename, lineNum, err)
+		}
+	}
+	return scanner.Err()
+}
+
+// New creates a host key callback from the given OpenSSH host key
+// files. The returned callback is for use in
+// ssh.ClientConfig.HostKeyCallback.
+func New(files ...string) (ssh.HostKeyCallback, error) {
+	db := newHostKeyDB()
+	for _, fn := range files {
+		f, err := os.Open(fn)
+		if err != nil {
+			return nil, err
+		}
+		defer f.Close()
+		if err := db.Read(f, fn); err != nil {
+			return nil, err
+		}
+	}
+
+	var certChecker ssh.CertChecker
+	certChecker.IsHostAuthority = db.IsHostAuthority
+	certChecker.IsRevoked = db.IsRevoked
+	certChecker.HostKeyFallback = db.check
+
+	return certChecker.CheckHostKey, nil
+}
+
+// Normalize normalizes an address into the form used in known_hosts
+func Normalize(address string) string {
+	host, port, err := net.SplitHostPort(address)
+	if err != nil {
+		host = address
+		port = "22"
+	}
+	entry := host
+	if port != "22" {
+		entry = "[" + entry + "]:" + port
+	} else if strings.Contains(host, ":") && !strings.HasPrefix(host, "[") {
+		entry = "[" + entry + "]"
+	}
+	return entry
+}
+
+// Line returns a line to add append to the known_hosts files.
+func Line(addresses []string, key ssh.PublicKey) string {
+	var trimmed []string
+	for _, a := range addresses {
+		trimmed = append(trimmed, Normalize(a))
+	}
+
+	return strings.Join(trimmed, ",") + " " + serialize(key)
+}
+
+// HashHostname hashes the given hostname. The hostname is not
+// normalized before hashing.
+func HashHostname(hostname string) string {
+	// TODO(hanwen): check if we can safely normalize this always.
+	salt := make([]byte, sha1.Size)
+
+	_, err := rand.Read(salt)
+	if err != nil {
+		panic(fmt.Sprintf("crypto/rand failure %v", err))
+	}
+
+	hash := hashHost(hostname, salt)
+	return encodeHash(sha1HashType, salt, hash)
+}
+
+func decodeHash(encoded string) (hashType string, salt, hash []byte, err error) {
+	if len(encoded) == 0 || encoded[0] != '|' {
+		err = errors.New("knownhosts: hashed host must start with '|'")
+		return
+	}
+	components := strings.Split(encoded, "|")
+	if len(components) != 4 {
+		err = fmt.Errorf("knownhosts: got %d components, want 3", len(components))
+		return
+	}
+
+	hashType = components[1]
+	if salt, err = base64.StdEncoding.DecodeString(components[2]); err != nil {
+		return
+	}
+	if hash, err = base64.StdEncoding.DecodeString(components[3]); err != nil {
+		return
+	}
+	return
+}
+
+func encodeHash(typ string, salt []byte, hash []byte) string {
+	return strings.Join([]string{"",
+		typ,
+		base64.StdEncoding.EncodeToString(salt),
+		base64.StdEncoding.EncodeToString(hash),
+	}, "|")
+}
+
+// See https://android.googlesource.com/platform/external/openssh/+/ab28f5495c85297e7a597c1ba62e996416da7c7e/hostfile.c#120
+func hashHost(hostname string, salt []byte) []byte {
+	mac := hmac.New(sha1.New, salt)
+	mac.Write([]byte(hostname))
+	return mac.Sum(nil)
+}
+
+type hashedHost struct {
+	salt []byte
+	hash []byte
+}
+
+const sha1HashType = "1"
+
+func newHashedHost(encoded string) (*hashedHost, error) {
+	typ, salt, hash, err := decodeHash(encoded)
+	if err != nil {
+		return nil, err
+	}
+
+	// The type field seems for future algorithm agility, but it's
+	// actually hardcoded in openssh currently, see
+	// https://android.googlesource.com/platform/external/openssh/+/ab28f5495c85297e7a597c1ba62e996416da7c7e/hostfile.c#120
+	if typ != sha1HashType {
+		return nil, fmt.Errorf("knownhosts: got hash type %s, must be '1'", typ)
+	}
+
+	return &hashedHost{salt: salt, hash: hash}, nil
+}
+
+func (h *hashedHost) match(addrs []addr) bool {
+	for _, a := range addrs {
+		if bytes.Equal(hashHost(Normalize(a.String()), h.salt), h.hash) {
+			return true
+		}
+	}
+	return false
+}
diff --git a/vendor/golang.org/x/crypto/ssh/transport.go b/vendor/golang.org/x/crypto/ssh/transport.go
index 01150eb89..f6fae1db4 100644
--- a/vendor/golang.org/x/crypto/ssh/transport.go
+++ b/vendor/golang.org/x/crypto/ssh/transport.go
@@ -6,6 +6,7 @@ package ssh
 
 import (
 	"bufio"
+	"bytes"
 	"errors"
 	"io"
 	"log"
@@ -232,52 +233,22 @@ var (
 	clientKeys = direction{[]byte{'A'}, []byte{'C'}, []byte{'E'}}
 )
 
-// generateKeys generates key material for IV, MAC and encryption.
-func generateKeys(d direction, algs directionAlgorithms, kex *kexResult) (iv, key, macKey []byte) {
-	cipherMode := cipherModes[algs.Cipher]
-	macMode := macModes[algs.MAC]
-
-	iv = make([]byte, cipherMode.ivSize)
-	key = make([]byte, cipherMode.keySize)
-	macKey = make([]byte, macMode.keySize)
-
-	generateKeyMaterial(iv, d.ivTag, kex)
-	generateKeyMaterial(key, d.keyTag, kex)
-	generateKeyMaterial(macKey, d.macKeyTag, kex)
-	return
-}
-
 // setupKeys sets the cipher and MAC keys from kex.K, kex.H and sessionId, as
 // described in RFC 4253, section 6.4. direction should either be serverKeys
 // (to setup server->client keys) or clientKeys (for client->server keys).
 func newPacketCipher(d direction, algs directionAlgorithms, kex *kexResult) (packetCipher, error) {
-	iv, key, macKey := generateKeys(d, algs, kex)
+	cipherMode := cipherModes[algs.Cipher]
+	macMode := macModes[algs.MAC]
 
-	if algs.Cipher == gcmCipherID {
-		return newGCMCipher(iv, key)
-	}
+	iv := make([]byte, cipherMode.ivSize)
+	key := make([]byte, cipherMode.keySize)
+	macKey := make([]byte, macMode.keySize)
 
-	if algs.Cipher == aes128cbcID {
-		return newAESCBCCipher(iv, key, macKey, algs)
-	}
+	generateKeyMaterial(iv, d.ivTag, kex)
+	generateKeyMaterial(key, d.keyTag, kex)
+	generateKeyMaterial(macKey, d.macKeyTag, kex)
 
-	if algs.Cipher == tripledescbcID {
-		return newTripleDESCBCCipher(iv, key, macKey, algs)
-	}
-
-	c := &streamPacketCipher{
-		mac: macModes[algs.MAC].new(macKey),
-		etm: macModes[algs.MAC].etm,
-	}
-	c.macResult = make([]byte, c.mac.Size())
-
-	var err error
-	c.cipher, err = cipherModes[algs.Cipher].createStream(key, iv)
-	if err != nil {
-		return nil, err
-	}
-
-	return c, nil
+	return cipherModes[algs.Cipher].create(key, iv, macKey, algs)
 }
 
 // generateKeyMaterial fills out with key material generated from tag, K, H
@@ -342,7 +313,7 @@ func readVersion(r io.Reader) ([]byte, error) {
 	var ok bool
 	var buf [1]byte
 
-	for len(versionString) < maxVersionStringBytes {
+	for length := 0; length < maxVersionStringBytes; length++ {
 		_, err := io.ReadFull(r, buf[:])
 		if err != nil {
 			return nil, err
@@ -350,6 +321,13 @@ func readVersion(r io.Reader) ([]byte, error) {
 		// The RFC says that the version should be terminated with \r\n
 		// but several SSH servers actually only send a \n.
 		if buf[0] == '\n' {
+			if !bytes.HasPrefix(versionString, []byte("SSH-")) {
+				// RFC 4253 says we need to ignore all version string lines
+				// except the one containing the SSH version (provided that
+				// all the lines do not exceed 255 bytes in total).
+				versionString = versionString[:0]
+				continue
+			}
 			ok = true
 			break
 		}
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 6622319d8..45a53cd41 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -2257,6 +2257,12 @@
 			"revision": "453249f01cfeb54c3d549ddb75ff152ca243f9d8",
 			"revisionTime": "2017-02-08T20:51:15Z"
 		},
+		{
+			"checksumSHA1": "hfABw6DX9B4Ma+88qDDGz9qY45s=",
+			"path": "golang.org/x/crypto/internal/chacha20",
+			"revision": "9de5f2eaf759b4c4550b3db39fed2e9e5f86f45c",
+			"revisionTime": "2018-02-11T11:39:43Z"
+		},
 		{
 			"checksumSHA1": "MCeXr2RNeiG1XG6V+er1OR0qyeo=",
 			"path": "golang.org/x/crypto/md4",
@@ -2300,10 +2306,16 @@
 			"revisionTime": "2017-02-08T20:51:15Z"
 		},
 		{
-			"checksumSHA1": "pySTR3iSeU7FhjbBnQPNxgyIa4I=",
+			"checksumSHA1": "kVKE0OX1Xdw5mG7XKT86DLLKE2I=",
+			"path": "golang.org/x/crypto/poly1305",
+			"revision": "9de5f2eaf759b4c4550b3db39fed2e9e5f86f45c",
+			"revisionTime": "2018-02-11T11:39:43Z"
+		},
+		{
+			"checksumSHA1": "ZK4HWtg3hJzayz0RRcc6qHpkums=",
 			"path": "golang.org/x/crypto/ssh",
-			"revision": "d585fd2cc9195196078f516b69daff6744ef5e84",
-			"revisionTime": "2017-12-16T04:08:15Z",
+			"revision": "9de5f2eaf759b4c4550b3db39fed2e9e5f86f45c",
+			"revisionTime": "2018-02-11T11:39:43Z",
 			"version": "master",
 			"versionExact": "master"
 		},
@@ -2315,6 +2327,14 @@
 			"version": "master",
 			"versionExact": "master"
 		},
+		{
+			"checksumSHA1": "He3gVAAa2cym6sK3f2tgZoCMdOk=",
+			"path": "golang.org/x/crypto/ssh/knownhosts",
+			"revision": "650f4a345ab4e5b245a3034b110ebc7299e68186",
+			"revisionTime": "2017-09-27T09:16:38Z",
+			"version": "master",
+			"versionExact": "master"
+		},
 		{
 			"checksumSHA1": "9jjO5GjLa0XF/nfWihF02RoH4qc=",
 			"path": "golang.org/x/net/context",

From 1e7fd1c4ea370df820031caa0690e457c38e385d Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Wed, 14 Feb 2018 14:02:30 -0500
Subject: [PATCH 3/5] add test for host key validation

This tests basic known_hosts validation for the ssh communicator.
---
 communicator/ssh/communicator_test.go | 70 +++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/communicator/ssh/communicator_test.go b/communicator/ssh/communicator_test.go
index b2344fa55..5064a7e82 100644
--- a/communicator/ssh/communicator_test.go
+++ b/communicator/ssh/communicator_test.go
@@ -5,6 +5,7 @@ package ssh
 import (
 	"bufio"
 	"bytes"
+	"encoding/base64"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -13,6 +14,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -171,6 +173,74 @@ func TestStart(t *testing.T) {
 	}
 }
 
+func TestHostKey(t *testing.T) {
+	// get the server's public key
+	signer, err := ssh.ParsePrivateKey([]byte(testServerPrivateKey))
+	if err != nil {
+		panic("unable to parse private key: " + err.Error())
+	}
+	pubKey := fmt.Sprintf("ssh-rsa %s", base64.StdEncoding.EncodeToString(signer.PublicKey().Marshal()))
+
+	address := newMockLineServer(t)
+	host, p, _ := net.SplitHostPort(address)
+	port, _ := strconv.Atoi(p)
+
+	connInfo := &connectionInfo{
+		User:     "user",
+		Password: "pass",
+		Host:     host,
+		HostKey:  pubKey,
+		Port:     port,
+		Timeout:  "30s",
+	}
+
+	cfg, err := prepareSSHConfig(connInfo)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	c := &Communicator{
+		connInfo: connInfo,
+		config:   cfg,
+	}
+
+	var cmd remote.Cmd
+	stdout := new(bytes.Buffer)
+	cmd.Command = "echo foo"
+	cmd.Stdout = stdout
+
+	if err := c.Start(&cmd); err != nil {
+		t.Fatal(err)
+	}
+	if err := c.Disconnect(); err != nil {
+		t.Fatal(err)
+	}
+
+	// now check with the wrong HostKey
+	address = newMockLineServer(t)
+	_, p, _ = net.SplitHostPort(address)
+	port, _ = strconv.Atoi(p)
+
+	connInfo.HostKey = testClientPublicKey
+	connInfo.Port = port
+
+	cfg, err = prepareSSHConfig(connInfo)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	c = &Communicator{
+		connInfo: connInfo,
+		config:   cfg,
+	}
+
+	err = c.Start(&cmd)
+	if err == nil || !strings.Contains(err.Error(), "mismatch") {
+		t.Fatalf("expected host key mismatch, got error:%v", err)
+	}
+
+}
+
 func TestAccUploadFile(t *testing.T) {
 	// use the local ssh server and scp binary to check uploads
 	if ok := os.Getenv("SSH_UPLOAD_TEST"); ok == "" {

From bdfa97dbdb7b4cfa4168b0478f7eaabe6bc51105 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Wed, 14 Feb 2018 15:23:07 -0500
Subject: [PATCH 4/5] add tests for signed host certs

This checks that we can verify host certificates signed by a CA
---
 communicator/ssh/communicator_test.go | 109 ++++++++++++++++++++++----
 1 file changed, 94 insertions(+), 15 deletions(-)

diff --git a/communicator/ssh/communicator_test.go b/communicator/ssh/communicator_test.go
index 5064a7e82..9a2d715f2 100644
--- a/communicator/ssh/communicator_test.go
+++ b/communicator/ssh/communicator_test.go
@@ -52,21 +52,26 @@ gqnBycHj6AhEycjda75cs+0zybZvN4x65KZHOGW/O/7OAWEcZP5TPb3zf9ned3Hl
 NsZoFj52ponUM6+99A2CmezFCN16c4mbA//luWF+k3VVqR6BpkrhKw==
 -----END RSA PRIVATE KEY-----`
 
-var serverConfig = &ssh.ServerConfig{
-	PasswordCallback:  acceptUserPass("user", "pass"),
-	PublicKeyCallback: acceptPublicKey(testClientPublicKey),
-}
+// this cert was signed by the key from testCAPublicKey
+const testServerHostCert = `ssh-rsa-cert-v01@openssh.com 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`
 
-func init() {
-	// Parse and set the private key of the server, required to accept connections
-	signer, err := ssh.ParsePrivateKey([]byte(testServerPrivateKey))
-	if err != nil {
-		panic("unable to parse private key: " + err.Error())
+const testCAPublicKey = `ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCrozyZIhdEvalCn+eSzHH94cO9ykiywA13ntWI7mJcHBwYTeCYWG8E9zGXyp2iDOjCGudM0Tdt8o0OofKChk9Z/qiUN0G8y1kmaXBlBM3qA5R9NPpvMYMNkYLfX6ivtZCnqrsbzaoqN2Oc/7H2StHzJWh/XCGu9otQZA6vdv1oSmAsZOjw/xIGaGQqDUaLq21J280PP1qSbdJHf76iSHE+TWe3YpqV946JWM5tCh0DykZ10VznvxYpUjzhr07IN3tVKxOXbPnnU7lX6IaLIWgfzLqwSyheeux05c3JLF9iF4sFu8ou4hwQz1iuUTU1jxgwZP0w/bkXgFFs0949lW81`
+
+func newMockLineServer(t *testing.T, signer ssh.Signer) string {
+	serverConfig := &ssh.ServerConfig{
+		PasswordCallback:  acceptUserPass("user", "pass"),
+		PublicKeyCallback: acceptPublicKey(testClientPublicKey),
+	}
+
+	var err error
+	if signer == nil {
+		signer, err = ssh.ParsePrivateKey([]byte(testServerPrivateKey))
+		if err != nil {
+			t.Fatalf("unable to parse private key: %s", err)
+		}
 	}
 	serverConfig.AddHostKey(signer)
-}
 
-func newMockLineServer(t *testing.T) string {
 	l, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {
 		t.Fatalf("Unable to listen for connection: %s", err)
@@ -113,7 +118,7 @@ func newMockLineServer(t *testing.T) string {
 }
 
 func TestNew_Invalid(t *testing.T) {
-	address := newMockLineServer(t)
+	address := newMockLineServer(t, nil)
 	parts := strings.Split(address, ":")
 
 	r := &terraform.InstanceState{
@@ -141,7 +146,7 @@ func TestNew_Invalid(t *testing.T) {
 }
 
 func TestStart(t *testing.T) {
-	address := newMockLineServer(t)
+	address := newMockLineServer(t, nil)
 	parts := strings.Split(address, ":")
 
 	r := &terraform.InstanceState{
@@ -181,7 +186,7 @@ func TestHostKey(t *testing.T) {
 	}
 	pubKey := fmt.Sprintf("ssh-rsa %s", base64.StdEncoding.EncodeToString(signer.PublicKey().Marshal()))
 
-	address := newMockLineServer(t)
+	address := newMockLineServer(t, nil)
 	host, p, _ := net.SplitHostPort(address)
 	port, _ := strconv.Atoi(p)
 
@@ -217,7 +222,7 @@ func TestHostKey(t *testing.T) {
 	}
 
 	// now check with the wrong HostKey
-	address = newMockLineServer(t)
+	address = newMockLineServer(t, nil)
 	_, p, _ = net.SplitHostPort(address)
 	port, _ = strconv.Atoi(p)
 
@@ -238,7 +243,81 @@ func TestHostKey(t *testing.T) {
 	if err == nil || !strings.Contains(err.Error(), "mismatch") {
 		t.Fatalf("expected host key mismatch, got error:%v", err)
 	}
+}
 
+func TestHostCert(t *testing.T) {
+	pk, _, _, _, err := ssh.ParseAuthorizedKey([]byte(testServerHostCert))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	signer, err := ssh.ParsePrivateKey([]byte(testServerPrivateKey))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	signer, err = ssh.NewCertSigner(pk.(*ssh.Certificate), signer)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	address := newMockLineServer(t, signer)
+	host, p, _ := net.SplitHostPort(address)
+	port, _ := strconv.Atoi(p)
+
+	connInfo := &connectionInfo{
+		User:     "user",
+		Password: "pass",
+		Host:     host,
+		HostKey:  testCAPublicKey,
+		Port:     port,
+		Timeout:  "30s",
+	}
+
+	cfg, err := prepareSSHConfig(connInfo)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	c := &Communicator{
+		connInfo: connInfo,
+		config:   cfg,
+	}
+
+	var cmd remote.Cmd
+	stdout := new(bytes.Buffer)
+	cmd.Command = "echo foo"
+	cmd.Stdout = stdout
+
+	if err := c.Start(&cmd); err != nil {
+		t.Fatal(err)
+	}
+	if err := c.Disconnect(); err != nil {
+		t.Fatal(err)
+	}
+
+	// now check with the wrong HostKey
+	address = newMockLineServer(t, signer)
+	_, p, _ = net.SplitHostPort(address)
+	port, _ = strconv.Atoi(p)
+
+	connInfo.HostKey = testClientPublicKey
+	connInfo.Port = port
+
+	cfg, err = prepareSSHConfig(connInfo)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	c = &Communicator{
+		connInfo: connInfo,
+		config:   cfg,
+	}
+
+	err = c.Start(&cmd)
+	if err == nil || !strings.Contains(err.Error(), "authorities") {
+		t.Fatalf("expected host key mismatch, got error:%v", err)
+	}
 }
 
 func TestAccUploadFile(t *testing.T) {

From 194a4e88e21282e28d963d3f97df7e5cc556c610 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Wed, 14 Feb 2018 15:30:18 -0500
Subject: [PATCH 5/5] add host_key and bastion_host_key to the docs

---
 website/docs/provisioners/connection.html.markdown | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/website/docs/provisioners/connection.html.markdown b/website/docs/provisioners/connection.html.markdown
index 9a499bcab..10954f4d1 100644
--- a/website/docs/provisioners/connection.html.markdown
+++ b/website/docs/provisioners/connection.html.markdown
@@ -83,6 +83,9 @@ provisioner "file" {
 
 * `agent_identity` - The preferred identity from the ssh agent for authentication.
 
+* `host_key` - The public key from the remote host or the signing CA, used to
+  verify the connection.
+
 **Additional arguments only supported by the `winrm` connection type:**
 
 * `https` - Set to `true` to connect using HTTPS instead of HTTP.
@@ -100,6 +103,9 @@ The `ssh` connection also supports the following fields to facilitate connnectio
 * `bastion_host` - Setting this enables the bastion Host connection. This host
   will be connected to first, and then the `host` connection will be made from there.
 
+* `bastion_host_key` - The public key from the remote host or the signing CA,
+  used to verify the host connection.
+
 * `bastion_port` - The port to use connect to the bastion host. Defaults to the
   value of the `port` field.