go.crypto: initial code
Manual edits to README. Moved from main Go repository, deleted Makefiles, ran gofix -r go1rename. Tested with: go test code.google.com/p/go.crypto/... R=golang-dev, bradfitz CC=golang-dev https://golang.org/cl/5564059
This commit is contained in:
Russ Cox
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package ssh
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import (
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"crypto/dsa"
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"crypto/rsa"
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"math/big"
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"strconv"
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"sync"
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)
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// These are string constants in the SSH protocol.
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const (
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kexAlgoDH14SHA1 = "diffie-hellman-group14-sha1"
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hostAlgoRSA = "ssh-rsa"
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macSHA196 = "hmac-sha1-96"
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compressionNone = "none"
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serviceUserAuth = "ssh-userauth"
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serviceSSH = "ssh-connection"
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)
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var supportedKexAlgos = []string{kexAlgoDH14SHA1}
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var supportedHostKeyAlgos = []string{hostAlgoRSA}
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var supportedMACs = []string{macSHA196}
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var supportedCompressions = []string{compressionNone}
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// dhGroup is a multiplicative group suitable for implementing Diffie-Hellman key agreement.
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type dhGroup struct {
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g, p *big.Int
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}
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// dhGroup14 is the group called diffie-hellman-group14-sha1 in RFC 4253 and
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// Oakley Group 14 in RFC 3526.
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var dhGroup14 *dhGroup
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var dhGroup14Once sync.Once
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func initDHGroup14() {
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p, _ := new(big.Int).SetString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dhGroup14 = &dhGroup{
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g: new(big.Int).SetInt64(2),
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p: p,
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}
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}
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// UnexpectedMessageError results when the SSH message that we received didn't
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// match what we wanted.
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type UnexpectedMessageError struct {
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expected, got uint8
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}
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func (u UnexpectedMessageError) Error() string {
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return "ssh: unexpected message type " + strconv.Itoa(int(u.got)) + " (expected " + strconv.Itoa(int(u.expected)) + ")"
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}
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// ParseError results from a malformed SSH message.
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type ParseError struct {
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msgType uint8
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}
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func (p ParseError) Error() string {
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return "ssh: parse error in message type " + strconv.Itoa(int(p.msgType))
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}
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type handshakeMagics struct {
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clientVersion, serverVersion []byte
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clientKexInit, serverKexInit []byte
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}
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func findCommonAlgorithm(clientAlgos []string, serverAlgos []string) (commonAlgo string, ok bool) {
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for _, clientAlgo := range clientAlgos {
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for _, serverAlgo := range serverAlgos {
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if clientAlgo == serverAlgo {
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return clientAlgo, true
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}
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}
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}
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return
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}
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func findAgreedAlgorithms(transport *transport, clientKexInit, serverKexInit *kexInitMsg) (kexAlgo, hostKeyAlgo string, ok bool) {
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kexAlgo, ok = findCommonAlgorithm(clientKexInit.KexAlgos, serverKexInit.KexAlgos)
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if !ok {
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return
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}
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hostKeyAlgo, ok = findCommonAlgorithm(clientKexInit.ServerHostKeyAlgos, serverKexInit.ServerHostKeyAlgos)
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if !ok {
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return
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}
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transport.writer.cipherAlgo, ok = findCommonAlgorithm(clientKexInit.CiphersClientServer, serverKexInit.CiphersClientServer)
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if !ok {
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return
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}
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transport.reader.cipherAlgo, ok = findCommonAlgorithm(clientKexInit.CiphersServerClient, serverKexInit.CiphersServerClient)
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if !ok {
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return
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}
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transport.writer.macAlgo, ok = findCommonAlgorithm(clientKexInit.MACsClientServer, serverKexInit.MACsClientServer)
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if !ok {
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return
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}
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transport.reader.macAlgo, ok = findCommonAlgorithm(clientKexInit.MACsServerClient, serverKexInit.MACsServerClient)
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if !ok {
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return
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}
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transport.writer.compressionAlgo, ok = findCommonAlgorithm(clientKexInit.CompressionClientServer, serverKexInit.CompressionClientServer)
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if !ok {
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return
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}
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transport.reader.compressionAlgo, ok = findCommonAlgorithm(clientKexInit.CompressionServerClient, serverKexInit.CompressionServerClient)
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if !ok {
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return
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}
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ok = true
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return
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}
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// Cryptographic configuration common to both ServerConfig and ClientConfig.
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type CryptoConfig struct {
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// The allowed cipher algorithms. If unspecified then DefaultCipherOrder is
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// used.
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Ciphers []string
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}
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func (c *CryptoConfig) ciphers() []string {
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if c.Ciphers == nil {
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return DefaultCipherOrder
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}
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return c.Ciphers
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}
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// serialize a signed slice according to RFC 4254 6.6.
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func serializeSignature(algoname string, sig []byte) []byte {
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length := stringLength([]byte(algoname))
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length += stringLength(sig)
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ret := make([]byte, length)
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r := marshalString(ret, []byte(algoname))
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r = marshalString(r, sig)
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return ret
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}
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// serialize an rsa.PublicKey or dsa.PublicKey according to RFC 4253 6.6.
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func serializePublickey(key interface{}) []byte {
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algoname := algoName(key)
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switch key := key.(type) {
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case rsa.PublicKey:
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e := new(big.Int).SetInt64(int64(key.E))
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length := stringLength([]byte(algoname))
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length += intLength(e)
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length += intLength(key.N)
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ret := make([]byte, length)
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r := marshalString(ret, []byte(algoname))
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r = marshalInt(r, e)
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marshalInt(r, key.N)
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return ret
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case dsa.PublicKey:
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length := stringLength([]byte(algoname))
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length += intLength(key.P)
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length += intLength(key.Q)
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length += intLength(key.G)
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length += intLength(key.Y)
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ret := make([]byte, length)
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r := marshalString(ret, []byte(algoname))
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r = marshalInt(r, key.P)
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r = marshalInt(r, key.Q)
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r = marshalInt(r, key.G)
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marshalInt(r, key.Y)
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return ret
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}
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panic("unexpected key type")
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}
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func algoName(key interface{}) string {
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switch key.(type) {
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case rsa.PublicKey:
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return "ssh-rsa"
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case dsa.PublicKey:
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return "ssh-dss"
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}
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panic("unexpected key type")
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}
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// buildDataSignedForAuth returns the data that is signed in order to prove
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// posession of a private key. See RFC 4252, section 7.
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func buildDataSignedForAuth(sessionId []byte, req userAuthRequestMsg, algo, pubKey []byte) []byte {
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user := []byte(req.User)
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service := []byte(req.Service)
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method := []byte(req.Method)
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length := stringLength(sessionId)
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length += 1
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length += stringLength(user)
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length += stringLength(service)
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length += stringLength(method)
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length += 1
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length += stringLength(algo)
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length += stringLength(pubKey)
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ret := make([]byte, length)
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r := marshalString(ret, sessionId)
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r[0] = msgUserAuthRequest
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r = r[1:]
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r = marshalString(r, user)
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r = marshalString(r, service)
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r = marshalString(r, method)
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r[0] = 1
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r = r[1:]
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r = marshalString(r, algo)
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r = marshalString(r, pubKey)
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return ret
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}
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// safeString sanitises s according to RFC 4251, section 9.2.
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// All control characters except tab, carriage return and newline are
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// replaced by 0x20.
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func safeString(s string) string {
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out := []byte(s)
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for i, c := range out {
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if c < 0x20 && c != 0xd && c != 0xa && c != 0x9 {
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out[i] = 0x20
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}
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}
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return string(out)
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}
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