1100 lines
28 KiB
Go
1100 lines
28 KiB
Go
// Copyright 2012 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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"bytes"
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"crypto"
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"crypto/dsa"
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/md5"
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"crypto/rsa"
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"crypto/sha256"
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"crypto/x509"
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"encoding/asn1"
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"encoding/base64"
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"encoding/hex"
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"encoding/pem"
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"errors"
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"fmt"
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"io"
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"math/big"
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"strings"
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"golang.org/x/crypto/ed25519"
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)
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// These constants represent the algorithm names for key types supported by this
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// package.
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const (
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KeyAlgoRSA = "ssh-rsa"
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KeyAlgoDSA = "ssh-dss"
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KeyAlgoECDSA256 = "ecdsa-sha2-nistp256"
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KeyAlgoECDSA384 = "ecdsa-sha2-nistp384"
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KeyAlgoECDSA521 = "ecdsa-sha2-nistp521"
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KeyAlgoED25519 = "ssh-ed25519"
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)
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// These constants represent non-default signature algorithms that are supported
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// as algorithm parameters to AlgorithmSigner.SignWithAlgorithm methods. See
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// [PROTOCOL.agent] section 4.5.1 and
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// https://tools.ietf.org/html/draft-ietf-curdle-rsa-sha2-10
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const (
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SigAlgoRSA = "ssh-rsa"
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SigAlgoRSASHA2256 = "rsa-sha2-256"
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SigAlgoRSASHA2512 = "rsa-sha2-512"
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)
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// parsePubKey parses a public key of the given algorithm.
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// Use ParsePublicKey for keys with prepended algorithm.
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func parsePubKey(in []byte, algo string) (pubKey PublicKey, rest []byte, err error) {
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switch algo {
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case KeyAlgoRSA:
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return parseRSA(in)
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case KeyAlgoDSA:
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return parseDSA(in)
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case KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521:
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return parseECDSA(in)
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case KeyAlgoED25519:
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return parseED25519(in)
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case CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01, CertAlgoED25519v01:
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cert, err := parseCert(in, certToPrivAlgo(algo))
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if err != nil {
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return nil, nil, err
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}
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return cert, nil, nil
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}
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return nil, nil, fmt.Errorf("ssh: unknown key algorithm: %v", algo)
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}
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// parseAuthorizedKey parses a public key in OpenSSH authorized_keys format
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// (see sshd(8) manual page) once the options and key type fields have been
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// removed.
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func parseAuthorizedKey(in []byte) (out PublicKey, comment string, err error) {
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in = bytes.TrimSpace(in)
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i := bytes.IndexAny(in, " \t")
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if i == -1 {
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i = len(in)
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}
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base64Key := in[:i]
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key := make([]byte, base64.StdEncoding.DecodedLen(len(base64Key)))
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n, err := base64.StdEncoding.Decode(key, base64Key)
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if err != nil {
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return nil, "", err
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}
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key = key[:n]
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out, err = ParsePublicKey(key)
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if err != nil {
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return nil, "", err
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}
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comment = string(bytes.TrimSpace(in[i:]))
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return out, comment, nil
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}
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// ParseKnownHosts parses an entry in the format of the known_hosts file.
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//
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// The known_hosts format is documented in the sshd(8) manual page. This
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// function will parse a single entry from in. On successful return, marker
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// will contain the optional marker value (i.e. "cert-authority" or "revoked")
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// or else be empty, hosts will contain the hosts that this entry matches,
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// pubKey will contain the public key and comment will contain any trailing
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// comment at the end of the line. See the sshd(8) manual page for the various
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// forms that a host string can take.
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//
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// The unparsed remainder of the input will be returned in rest. This function
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// can be called repeatedly to parse multiple entries.
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//
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// If no entries were found in the input then err will be io.EOF. Otherwise a
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// non-nil err value indicates a parse error.
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func ParseKnownHosts(in []byte) (marker string, hosts []string, pubKey PublicKey, comment string, rest []byte, err error) {
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for len(in) > 0 {
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end := bytes.IndexByte(in, '\n')
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if end != -1 {
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rest = in[end+1:]
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in = in[:end]
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} else {
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rest = nil
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}
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end = bytes.IndexByte(in, '\r')
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if end != -1 {
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in = in[:end]
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}
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in = bytes.TrimSpace(in)
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if len(in) == 0 || in[0] == '#' {
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in = rest
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continue
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}
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i := bytes.IndexAny(in, " \t")
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if i == -1 {
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in = rest
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continue
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}
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// Strip out the beginning of the known_host key.
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// This is either an optional marker or a (set of) hostname(s).
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keyFields := bytes.Fields(in)
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if len(keyFields) < 3 || len(keyFields) > 5 {
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return "", nil, nil, "", nil, errors.New("ssh: invalid entry in known_hosts data")
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}
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// keyFields[0] is either "@cert-authority", "@revoked" or a comma separated
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// list of hosts
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marker := ""
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if keyFields[0][0] == '@' {
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marker = string(keyFields[0][1:])
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keyFields = keyFields[1:]
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}
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hosts := string(keyFields[0])
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// keyFields[1] contains the key type (e.g. “ssh-rsa”).
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// However, that information is duplicated inside the
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// base64-encoded key and so is ignored here.
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key := bytes.Join(keyFields[2:], []byte(" "))
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if pubKey, comment, err = parseAuthorizedKey(key); err != nil {
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return "", nil, nil, "", nil, err
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}
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return marker, strings.Split(hosts, ","), pubKey, comment, rest, nil
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}
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return "", nil, nil, "", nil, io.EOF
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}
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// ParseAuthorizedKeys parses a public key from an authorized_keys
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// file used in OpenSSH according to the sshd(8) manual page.
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func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []string, rest []byte, err error) {
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for len(in) > 0 {
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end := bytes.IndexByte(in, '\n')
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if end != -1 {
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rest = in[end+1:]
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in = in[:end]
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} else {
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rest = nil
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}
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end = bytes.IndexByte(in, '\r')
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if end != -1 {
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in = in[:end]
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}
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in = bytes.TrimSpace(in)
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if len(in) == 0 || in[0] == '#' {
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in = rest
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continue
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}
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i := bytes.IndexAny(in, " \t")
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if i == -1 {
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in = rest
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continue
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}
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if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
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return out, comment, options, rest, nil
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}
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// No key type recognised. Maybe there's an options field at
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// the beginning.
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var b byte
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inQuote := false
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var candidateOptions []string
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optionStart := 0
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for i, b = range in {
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isEnd := !inQuote && (b == ' ' || b == '\t')
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if (b == ',' && !inQuote) || isEnd {
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if i-optionStart > 0 {
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candidateOptions = append(candidateOptions, string(in[optionStart:i]))
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}
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optionStart = i + 1
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}
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if isEnd {
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break
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}
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if b == '"' && (i == 0 || (i > 0 && in[i-1] != '\\')) {
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inQuote = !inQuote
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}
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}
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for i < len(in) && (in[i] == ' ' || in[i] == '\t') {
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i++
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}
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if i == len(in) {
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// Invalid line: unmatched quote
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in = rest
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continue
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}
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in = in[i:]
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i = bytes.IndexAny(in, " \t")
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if i == -1 {
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in = rest
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continue
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}
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if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
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options = candidateOptions
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return out, comment, options, rest, nil
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}
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in = rest
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continue
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}
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return nil, "", nil, nil, errors.New("ssh: no key found")
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}
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// ParsePublicKey parses an SSH public key formatted for use in
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// the SSH wire protocol according to RFC 4253, section 6.6.
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func ParsePublicKey(in []byte) (out PublicKey, err error) {
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algo, in, ok := parseString(in)
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if !ok {
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return nil, errShortRead
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}
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var rest []byte
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out, rest, err = parsePubKey(in, string(algo))
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if len(rest) > 0 {
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return nil, errors.New("ssh: trailing junk in public key")
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}
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return out, err
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}
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// MarshalAuthorizedKey serializes key for inclusion in an OpenSSH
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// authorized_keys file. The return value ends with newline.
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func MarshalAuthorizedKey(key PublicKey) []byte {
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b := &bytes.Buffer{}
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b.WriteString(key.Type())
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b.WriteByte(' ')
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e := base64.NewEncoder(base64.StdEncoding, b)
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e.Write(key.Marshal())
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e.Close()
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b.WriteByte('\n')
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return b.Bytes()
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}
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// PublicKey is an abstraction of different types of public keys.
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type PublicKey interface {
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// Type returns the key's type, e.g. "ssh-rsa".
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Type() string
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// Marshal returns the serialized key data in SSH wire format,
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// with the name prefix. To unmarshal the returned data, use
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// the ParsePublicKey function.
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Marshal() []byte
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// Verify that sig is a signature on the given data using this
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// key. This function will hash the data appropriately first.
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Verify(data []byte, sig *Signature) error
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}
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// CryptoPublicKey, if implemented by a PublicKey,
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// returns the underlying crypto.PublicKey form of the key.
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type CryptoPublicKey interface {
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CryptoPublicKey() crypto.PublicKey
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}
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// A Signer can create signatures that verify against a public key.
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type Signer interface {
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// PublicKey returns an associated PublicKey instance.
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PublicKey() PublicKey
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// Sign returns raw signature for the given data. This method
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// will apply the hash specified for the keytype to the data.
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Sign(rand io.Reader, data []byte) (*Signature, error)
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}
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// A AlgorithmSigner is a Signer that also supports specifying a specific
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// algorithm to use for signing.
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type AlgorithmSigner interface {
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Signer
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// SignWithAlgorithm is like Signer.Sign, but allows specification of a
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// non-default signing algorithm. See the SigAlgo* constants in this
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// package for signature algorithms supported by this package. Callers may
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// pass an empty string for the algorithm in which case the AlgorithmSigner
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// will use its default algorithm.
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SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error)
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}
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type rsaPublicKey rsa.PublicKey
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func (r *rsaPublicKey) Type() string {
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return "ssh-rsa"
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}
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// parseRSA parses an RSA key according to RFC 4253, section 6.6.
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func parseRSA(in []byte) (out PublicKey, rest []byte, err error) {
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var w struct {
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E *big.Int
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N *big.Int
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Rest []byte `ssh:"rest"`
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}
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if err := Unmarshal(in, &w); err != nil {
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return nil, nil, err
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}
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if w.E.BitLen() > 24 {
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return nil, nil, errors.New("ssh: exponent too large")
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}
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e := w.E.Int64()
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if e < 3 || e&1 == 0 {
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return nil, nil, errors.New("ssh: incorrect exponent")
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}
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var key rsa.PublicKey
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key.E = int(e)
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key.N = w.N
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return (*rsaPublicKey)(&key), w.Rest, nil
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}
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func (r *rsaPublicKey) Marshal() []byte {
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e := new(big.Int).SetInt64(int64(r.E))
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// RSA publickey struct layout should match the struct used by
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// parseRSACert in the x/crypto/ssh/agent package.
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wirekey := struct {
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Name string
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E *big.Int
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N *big.Int
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}{
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KeyAlgoRSA,
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e,
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r.N,
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}
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return Marshal(&wirekey)
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}
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func (r *rsaPublicKey) Verify(data []byte, sig *Signature) error {
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var hash crypto.Hash
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switch sig.Format {
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case SigAlgoRSA:
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hash = crypto.SHA1
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case SigAlgoRSASHA2256:
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hash = crypto.SHA256
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case SigAlgoRSASHA2512:
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hash = crypto.SHA512
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default:
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return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, r.Type())
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}
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h := hash.New()
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h.Write(data)
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digest := h.Sum(nil)
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return rsa.VerifyPKCS1v15((*rsa.PublicKey)(r), hash, digest, sig.Blob)
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}
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func (r *rsaPublicKey) CryptoPublicKey() crypto.PublicKey {
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return (*rsa.PublicKey)(r)
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}
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type dsaPublicKey dsa.PublicKey
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func (k *dsaPublicKey) Type() string {
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return "ssh-dss"
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}
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func checkDSAParams(param *dsa.Parameters) error {
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// SSH specifies FIPS 186-2, which only provided a single size
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// (1024 bits) DSA key. FIPS 186-3 allows for larger key
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// sizes, which would confuse SSH.
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if l := param.P.BitLen(); l != 1024 {
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return fmt.Errorf("ssh: unsupported DSA key size %d", l)
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}
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return nil
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}
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// parseDSA parses an DSA key according to RFC 4253, section 6.6.
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func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
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var w struct {
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P, Q, G, Y *big.Int
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Rest []byte `ssh:"rest"`
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}
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if err := Unmarshal(in, &w); err != nil {
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return nil, nil, err
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}
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param := dsa.Parameters{
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P: w.P,
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Q: w.Q,
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G: w.G,
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}
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if err := checkDSAParams(¶m); err != nil {
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return nil, nil, err
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}
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key := &dsaPublicKey{
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Parameters: param,
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Y: w.Y,
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}
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return key, w.Rest, nil
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}
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func (k *dsaPublicKey) Marshal() []byte {
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// DSA publickey struct layout should match the struct used by
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// parseDSACert in the x/crypto/ssh/agent package.
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w := struct {
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Name string
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P, Q, G, Y *big.Int
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}{
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k.Type(),
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k.P,
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k.Q,
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k.G,
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k.Y,
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}
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return Marshal(&w)
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}
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func (k *dsaPublicKey) Verify(data []byte, sig *Signature) error {
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if sig.Format != k.Type() {
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return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
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}
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h := crypto.SHA1.New()
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h.Write(data)
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digest := h.Sum(nil)
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// Per RFC 4253, section 6.6,
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// The value for 'dss_signature_blob' is encoded as a string containing
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// r, followed by s (which are 160-bit integers, without lengths or
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// padding, unsigned, and in network byte order).
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// For DSS purposes, sig.Blob should be exactly 40 bytes in length.
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if len(sig.Blob) != 40 {
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return errors.New("ssh: DSA signature parse error")
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}
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r := new(big.Int).SetBytes(sig.Blob[:20])
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s := new(big.Int).SetBytes(sig.Blob[20:])
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if dsa.Verify((*dsa.PublicKey)(k), digest, r, s) {
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return nil
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}
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return errors.New("ssh: signature did not verify")
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}
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func (k *dsaPublicKey) CryptoPublicKey() crypto.PublicKey {
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return (*dsa.PublicKey)(k)
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}
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type dsaPrivateKey struct {
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*dsa.PrivateKey
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}
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func (k *dsaPrivateKey) PublicKey() PublicKey {
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return (*dsaPublicKey)(&k.PrivateKey.PublicKey)
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}
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func (k *dsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
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return k.SignWithAlgorithm(rand, data, "")
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}
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func (k *dsaPrivateKey) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error) {
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if algorithm != "" && algorithm != k.PublicKey().Type() {
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return nil, fmt.Errorf("ssh: unsupported signature algorithm %s", algorithm)
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}
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h := crypto.SHA1.New()
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h.Write(data)
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digest := h.Sum(nil)
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r, s, err := dsa.Sign(rand, k.PrivateKey, digest)
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if err != nil {
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return nil, err
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}
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sig := make([]byte, 40)
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rb := r.Bytes()
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sb := s.Bytes()
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copy(sig[20-len(rb):20], rb)
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copy(sig[40-len(sb):], sb)
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return &Signature{
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Format: k.PublicKey().Type(),
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Blob: sig,
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}, nil
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}
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type ecdsaPublicKey ecdsa.PublicKey
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func (k *ecdsaPublicKey) Type() string {
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return "ecdsa-sha2-" + k.nistID()
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}
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func (k *ecdsaPublicKey) nistID() string {
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switch k.Params().BitSize {
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case 256:
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return "nistp256"
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case 384:
|
|
return "nistp384"
|
|
case 521:
|
|
return "nistp521"
|
|
}
|
|
panic("ssh: unsupported ecdsa key size")
|
|
}
|
|
|
|
type ed25519PublicKey ed25519.PublicKey
|
|
|
|
func (k ed25519PublicKey) Type() string {
|
|
return KeyAlgoED25519
|
|
}
|
|
|
|
func parseED25519(in []byte) (out PublicKey, rest []byte, err error) {
|
|
var w struct {
|
|
KeyBytes []byte
|
|
Rest []byte `ssh:"rest"`
|
|
}
|
|
|
|
if err := Unmarshal(in, &w); err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
key := ed25519.PublicKey(w.KeyBytes)
|
|
|
|
return (ed25519PublicKey)(key), w.Rest, nil
|
|
}
|
|
|
|
func (k ed25519PublicKey) Marshal() []byte {
|
|
w := struct {
|
|
Name string
|
|
KeyBytes []byte
|
|
}{
|
|
KeyAlgoED25519,
|
|
[]byte(k),
|
|
}
|
|
return Marshal(&w)
|
|
}
|
|
|
|
func (k ed25519PublicKey) Verify(b []byte, sig *Signature) error {
|
|
if sig.Format != k.Type() {
|
|
return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
|
|
}
|
|
|
|
edKey := (ed25519.PublicKey)(k)
|
|
if ok := ed25519.Verify(edKey, b, sig.Blob); !ok {
|
|
return errors.New("ssh: signature did not verify")
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func (k ed25519PublicKey) CryptoPublicKey() crypto.PublicKey {
|
|
return ed25519.PublicKey(k)
|
|
}
|
|
|
|
func supportedEllipticCurve(curve elliptic.Curve) bool {
|
|
return curve == elliptic.P256() || curve == elliptic.P384() || curve == elliptic.P521()
|
|
}
|
|
|
|
// ecHash returns the hash to match the given elliptic curve, see RFC
|
|
// 5656, section 6.2.1
|
|
func ecHash(curve elliptic.Curve) crypto.Hash {
|
|
bitSize := curve.Params().BitSize
|
|
switch {
|
|
case bitSize <= 256:
|
|
return crypto.SHA256
|
|
case bitSize <= 384:
|
|
return crypto.SHA384
|
|
}
|
|
return crypto.SHA512
|
|
}
|
|
|
|
// parseECDSA parses an ECDSA key according to RFC 5656, section 3.1.
|
|
func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
|
|
var w struct {
|
|
Curve string
|
|
KeyBytes []byte
|
|
Rest []byte `ssh:"rest"`
|
|
}
|
|
|
|
if err := Unmarshal(in, &w); err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
key := new(ecdsa.PublicKey)
|
|
|
|
switch w.Curve {
|
|
case "nistp256":
|
|
key.Curve = elliptic.P256()
|
|
case "nistp384":
|
|
key.Curve = elliptic.P384()
|
|
case "nistp521":
|
|
key.Curve = elliptic.P521()
|
|
default:
|
|
return nil, nil, errors.New("ssh: unsupported curve")
|
|
}
|
|
|
|
key.X, key.Y = elliptic.Unmarshal(key.Curve, w.KeyBytes)
|
|
if key.X == nil || key.Y == nil {
|
|
return nil, nil, errors.New("ssh: invalid curve point")
|
|
}
|
|
return (*ecdsaPublicKey)(key), w.Rest, nil
|
|
}
|
|
|
|
func (k *ecdsaPublicKey) Marshal() []byte {
|
|
// See RFC 5656, section 3.1.
|
|
keyBytes := elliptic.Marshal(k.Curve, k.X, k.Y)
|
|
// ECDSA publickey struct layout should match the struct used by
|
|
// parseECDSACert in the x/crypto/ssh/agent package.
|
|
w := struct {
|
|
Name string
|
|
ID string
|
|
Key []byte
|
|
}{
|
|
k.Type(),
|
|
k.nistID(),
|
|
keyBytes,
|
|
}
|
|
|
|
return Marshal(&w)
|
|
}
|
|
|
|
func (k *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
|
|
if sig.Format != k.Type() {
|
|
return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
|
|
}
|
|
|
|
h := ecHash(k.Curve).New()
|
|
h.Write(data)
|
|
digest := h.Sum(nil)
|
|
|
|
// Per RFC 5656, section 3.1.2,
|
|
// The ecdsa_signature_blob value has the following specific encoding:
|
|
// mpint r
|
|
// mpint s
|
|
var ecSig struct {
|
|
R *big.Int
|
|
S *big.Int
|
|
}
|
|
|
|
if err := Unmarshal(sig.Blob, &ecSig); err != nil {
|
|
return err
|
|
}
|
|
|
|
if ecdsa.Verify((*ecdsa.PublicKey)(k), digest, ecSig.R, ecSig.S) {
|
|
return nil
|
|
}
|
|
return errors.New("ssh: signature did not verify")
|
|
}
|
|
|
|
func (k *ecdsaPublicKey) CryptoPublicKey() crypto.PublicKey {
|
|
return (*ecdsa.PublicKey)(k)
|
|
}
|
|
|
|
// NewSignerFromKey takes an *rsa.PrivateKey, *dsa.PrivateKey,
|
|
// *ecdsa.PrivateKey or any other crypto.Signer and returns a
|
|
// corresponding Signer instance. ECDSA keys must use P-256, P-384 or
|
|
// P-521. DSA keys must use parameter size L1024N160.
|
|
func NewSignerFromKey(key interface{}) (Signer, error) {
|
|
switch key := key.(type) {
|
|
case crypto.Signer:
|
|
return NewSignerFromSigner(key)
|
|
case *dsa.PrivateKey:
|
|
return newDSAPrivateKey(key)
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %T", key)
|
|
}
|
|
}
|
|
|
|
func newDSAPrivateKey(key *dsa.PrivateKey) (Signer, error) {
|
|
if err := checkDSAParams(&key.PublicKey.Parameters); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return &dsaPrivateKey{key}, nil
|
|
}
|
|
|
|
type wrappedSigner struct {
|
|
signer crypto.Signer
|
|
pubKey PublicKey
|
|
}
|
|
|
|
// NewSignerFromSigner takes any crypto.Signer implementation and
|
|
// returns a corresponding Signer interface. This can be used, for
|
|
// example, with keys kept in hardware modules.
|
|
func NewSignerFromSigner(signer crypto.Signer) (Signer, error) {
|
|
pubKey, err := NewPublicKey(signer.Public())
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return &wrappedSigner{signer, pubKey}, nil
|
|
}
|
|
|
|
func (s *wrappedSigner) PublicKey() PublicKey {
|
|
return s.pubKey
|
|
}
|
|
|
|
func (s *wrappedSigner) Sign(rand io.Reader, data []byte) (*Signature, error) {
|
|
return s.SignWithAlgorithm(rand, data, "")
|
|
}
|
|
|
|
func (s *wrappedSigner) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error) {
|
|
var hashFunc crypto.Hash
|
|
|
|
if _, ok := s.pubKey.(*rsaPublicKey); ok {
|
|
// RSA keys support a few hash functions determined by the requested signature algorithm
|
|
switch algorithm {
|
|
case "", SigAlgoRSA:
|
|
algorithm = SigAlgoRSA
|
|
hashFunc = crypto.SHA1
|
|
case SigAlgoRSASHA2256:
|
|
hashFunc = crypto.SHA256
|
|
case SigAlgoRSASHA2512:
|
|
hashFunc = crypto.SHA512
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported signature algorithm %s", algorithm)
|
|
}
|
|
} else {
|
|
// The only supported algorithm for all other key types is the same as the type of the key
|
|
if algorithm == "" {
|
|
algorithm = s.pubKey.Type()
|
|
} else if algorithm != s.pubKey.Type() {
|
|
return nil, fmt.Errorf("ssh: unsupported signature algorithm %s", algorithm)
|
|
}
|
|
|
|
switch key := s.pubKey.(type) {
|
|
case *dsaPublicKey:
|
|
hashFunc = crypto.SHA1
|
|
case *ecdsaPublicKey:
|
|
hashFunc = ecHash(key.Curve)
|
|
case ed25519PublicKey:
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %T", key)
|
|
}
|
|
}
|
|
|
|
var digest []byte
|
|
if hashFunc != 0 {
|
|
h := hashFunc.New()
|
|
h.Write(data)
|
|
digest = h.Sum(nil)
|
|
} else {
|
|
digest = data
|
|
}
|
|
|
|
signature, err := s.signer.Sign(rand, digest, hashFunc)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// crypto.Signer.Sign is expected to return an ASN.1-encoded signature
|
|
// for ECDSA and DSA, but that's not the encoding expected by SSH, so
|
|
// re-encode.
|
|
switch s.pubKey.(type) {
|
|
case *ecdsaPublicKey, *dsaPublicKey:
|
|
type asn1Signature struct {
|
|
R, S *big.Int
|
|
}
|
|
asn1Sig := new(asn1Signature)
|
|
_, err := asn1.Unmarshal(signature, asn1Sig)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
switch s.pubKey.(type) {
|
|
case *ecdsaPublicKey:
|
|
signature = Marshal(asn1Sig)
|
|
|
|
case *dsaPublicKey:
|
|
signature = make([]byte, 40)
|
|
r := asn1Sig.R.Bytes()
|
|
s := asn1Sig.S.Bytes()
|
|
copy(signature[20-len(r):20], r)
|
|
copy(signature[40-len(s):40], s)
|
|
}
|
|
}
|
|
|
|
return &Signature{
|
|
Format: algorithm,
|
|
Blob: signature,
|
|
}, nil
|
|
}
|
|
|
|
// NewPublicKey takes an *rsa.PublicKey, *dsa.PublicKey, *ecdsa.PublicKey,
|
|
// or ed25519.PublicKey returns a corresponding PublicKey instance.
|
|
// ECDSA keys must use P-256, P-384 or P-521.
|
|
func NewPublicKey(key interface{}) (PublicKey, error) {
|
|
switch key := key.(type) {
|
|
case *rsa.PublicKey:
|
|
return (*rsaPublicKey)(key), nil
|
|
case *ecdsa.PublicKey:
|
|
if !supportedEllipticCurve(key.Curve) {
|
|
return nil, errors.New("ssh: only P-256, P-384 and P-521 EC keys are supported")
|
|
}
|
|
return (*ecdsaPublicKey)(key), nil
|
|
case *dsa.PublicKey:
|
|
return (*dsaPublicKey)(key), nil
|
|
case ed25519.PublicKey:
|
|
return (ed25519PublicKey)(key), nil
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %T", key)
|
|
}
|
|
}
|
|
|
|
// ParsePrivateKey returns a Signer from a PEM encoded private key. It supports
|
|
// the same keys as ParseRawPrivateKey.
|
|
func ParsePrivateKey(pemBytes []byte) (Signer, error) {
|
|
key, err := ParseRawPrivateKey(pemBytes)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return NewSignerFromKey(key)
|
|
}
|
|
|
|
// ParsePrivateKeyWithPassphrase returns a Signer from a PEM encoded private
|
|
// key and passphrase. It supports the same keys as
|
|
// ParseRawPrivateKeyWithPassphrase.
|
|
func ParsePrivateKeyWithPassphrase(pemBytes, passPhrase []byte) (Signer, error) {
|
|
key, err := ParseRawPrivateKeyWithPassphrase(pemBytes, passPhrase)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return NewSignerFromKey(key)
|
|
}
|
|
|
|
// encryptedBlock tells whether a private key is
|
|
// encrypted by examining its Proc-Type header
|
|
// for a mention of ENCRYPTED
|
|
// according to RFC 1421 Section 4.6.1.1.
|
|
func encryptedBlock(block *pem.Block) bool {
|
|
return strings.Contains(block.Headers["Proc-Type"], "ENCRYPTED")
|
|
}
|
|
|
|
// ParseRawPrivateKey returns a private key from a PEM encoded private key. It
|
|
// supports RSA (PKCS#1), PKCS#8, DSA (OpenSSL), and ECDSA private keys.
|
|
func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
|
|
block, _ := pem.Decode(pemBytes)
|
|
if block == nil {
|
|
return nil, errors.New("ssh: no key found")
|
|
}
|
|
|
|
if encryptedBlock(block) {
|
|
return nil, errors.New("ssh: cannot decode encrypted private keys")
|
|
}
|
|
|
|
switch block.Type {
|
|
case "RSA PRIVATE KEY":
|
|
return x509.ParsePKCS1PrivateKey(block.Bytes)
|
|
// RFC5208 - https://tools.ietf.org/html/rfc5208
|
|
case "PRIVATE KEY":
|
|
return x509.ParsePKCS8PrivateKey(block.Bytes)
|
|
case "EC PRIVATE KEY":
|
|
return x509.ParseECPrivateKey(block.Bytes)
|
|
case "DSA PRIVATE KEY":
|
|
return ParseDSAPrivateKey(block.Bytes)
|
|
case "OPENSSH PRIVATE KEY":
|
|
return parseOpenSSHPrivateKey(block.Bytes)
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %q", block.Type)
|
|
}
|
|
}
|
|
|
|
// ParseRawPrivateKeyWithPassphrase returns a private key decrypted with
|
|
// passphrase from a PEM encoded private key. If wrong passphrase, return
|
|
// x509.IncorrectPasswordError.
|
|
func ParseRawPrivateKeyWithPassphrase(pemBytes, passPhrase []byte) (interface{}, error) {
|
|
block, _ := pem.Decode(pemBytes)
|
|
if block == nil {
|
|
return nil, errors.New("ssh: no key found")
|
|
}
|
|
buf := block.Bytes
|
|
|
|
if encryptedBlock(block) {
|
|
if x509.IsEncryptedPEMBlock(block) {
|
|
var err error
|
|
buf, err = x509.DecryptPEMBlock(block, passPhrase)
|
|
if err != nil {
|
|
if err == x509.IncorrectPasswordError {
|
|
return nil, err
|
|
}
|
|
return nil, fmt.Errorf("ssh: cannot decode encrypted private keys: %v", err)
|
|
}
|
|
}
|
|
}
|
|
|
|
switch block.Type {
|
|
case "RSA PRIVATE KEY":
|
|
return x509.ParsePKCS1PrivateKey(buf)
|
|
case "EC PRIVATE KEY":
|
|
return x509.ParseECPrivateKey(buf)
|
|
case "DSA PRIVATE KEY":
|
|
return ParseDSAPrivateKey(buf)
|
|
case "OPENSSH PRIVATE KEY":
|
|
return parseOpenSSHPrivateKey(buf)
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %q", block.Type)
|
|
}
|
|
}
|
|
|
|
// ParseDSAPrivateKey returns a DSA private key from its ASN.1 DER encoding, as
|
|
// specified by the OpenSSL DSA man page.
|
|
func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
|
|
var k struct {
|
|
Version int
|
|
P *big.Int
|
|
Q *big.Int
|
|
G *big.Int
|
|
Pub *big.Int
|
|
Priv *big.Int
|
|
}
|
|
rest, err := asn1.Unmarshal(der, &k)
|
|
if err != nil {
|
|
return nil, errors.New("ssh: failed to parse DSA key: " + err.Error())
|
|
}
|
|
if len(rest) > 0 {
|
|
return nil, errors.New("ssh: garbage after DSA key")
|
|
}
|
|
|
|
return &dsa.PrivateKey{
|
|
PublicKey: dsa.PublicKey{
|
|
Parameters: dsa.Parameters{
|
|
P: k.P,
|
|
Q: k.Q,
|
|
G: k.G,
|
|
},
|
|
Y: k.Pub,
|
|
},
|
|
X: k.Priv,
|
|
}, nil
|
|
}
|
|
|
|
// Implemented based on the documentation at
|
|
// https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key
|
|
func parseOpenSSHPrivateKey(key []byte) (crypto.PrivateKey, error) {
|
|
const magic = "openssh-key-v1\x00"
|
|
if len(key) < len(magic) || string(key[:len(magic)]) != magic {
|
|
return nil, errors.New("ssh: invalid openssh private key format")
|
|
}
|
|
remaining := key[len(magic):]
|
|
|
|
var w struct {
|
|
CipherName string
|
|
KdfName string
|
|
KdfOpts string
|
|
NumKeys uint32
|
|
PubKey []byte
|
|
PrivKeyBlock []byte
|
|
}
|
|
|
|
if err := Unmarshal(remaining, &w); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
if w.KdfName != "none" || w.CipherName != "none" {
|
|
return nil, errors.New("ssh: cannot decode encrypted private keys")
|
|
}
|
|
|
|
pk1 := struct {
|
|
Check1 uint32
|
|
Check2 uint32
|
|
Keytype string
|
|
Rest []byte `ssh:"rest"`
|
|
}{}
|
|
|
|
if err := Unmarshal(w.PrivKeyBlock, &pk1); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
if pk1.Check1 != pk1.Check2 {
|
|
return nil, errors.New("ssh: checkint mismatch")
|
|
}
|
|
|
|
// we only handle ed25519 and rsa keys currently
|
|
switch pk1.Keytype {
|
|
case KeyAlgoRSA:
|
|
// https://github.com/openssh/openssh-portable/blob/master/sshkey.c#L2760-L2773
|
|
key := struct {
|
|
N *big.Int
|
|
E *big.Int
|
|
D *big.Int
|
|
Iqmp *big.Int
|
|
P *big.Int
|
|
Q *big.Int
|
|
Comment string
|
|
Pad []byte `ssh:"rest"`
|
|
}{}
|
|
|
|
if err := Unmarshal(pk1.Rest, &key); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
for i, b := range key.Pad {
|
|
if int(b) != i+1 {
|
|
return nil, errors.New("ssh: padding not as expected")
|
|
}
|
|
}
|
|
|
|
pk := &rsa.PrivateKey{
|
|
PublicKey: rsa.PublicKey{
|
|
N: key.N,
|
|
E: int(key.E.Int64()),
|
|
},
|
|
D: key.D,
|
|
Primes: []*big.Int{key.P, key.Q},
|
|
}
|
|
|
|
if err := pk.Validate(); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
pk.Precompute()
|
|
|
|
return pk, nil
|
|
case KeyAlgoED25519:
|
|
key := struct {
|
|
Pub []byte
|
|
Priv []byte
|
|
Comment string
|
|
Pad []byte `ssh:"rest"`
|
|
}{}
|
|
|
|
if err := Unmarshal(pk1.Rest, &key); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
if len(key.Priv) != ed25519.PrivateKeySize {
|
|
return nil, errors.New("ssh: private key unexpected length")
|
|
}
|
|
|
|
for i, b := range key.Pad {
|
|
if int(b) != i+1 {
|
|
return nil, errors.New("ssh: padding not as expected")
|
|
}
|
|
}
|
|
|
|
pk := ed25519.PrivateKey(make([]byte, ed25519.PrivateKeySize))
|
|
copy(pk, key.Priv)
|
|
return &pk, nil
|
|
default:
|
|
return nil, errors.New("ssh: unhandled key type")
|
|
}
|
|
}
|
|
|
|
// FingerprintLegacyMD5 returns the user presentation of the key's
|
|
// fingerprint as described by RFC 4716 section 4.
|
|
func FingerprintLegacyMD5(pubKey PublicKey) string {
|
|
md5sum := md5.Sum(pubKey.Marshal())
|
|
hexarray := make([]string, len(md5sum))
|
|
for i, c := range md5sum {
|
|
hexarray[i] = hex.EncodeToString([]byte{c})
|
|
}
|
|
return strings.Join(hexarray, ":")
|
|
}
|
|
|
|
// FingerprintSHA256 returns the user presentation of the key's
|
|
// fingerprint as unpadded base64 encoded sha256 hash.
|
|
// This format was introduced from OpenSSH 6.8.
|
|
// https://www.openssh.com/txt/release-6.8
|
|
// https://tools.ietf.org/html/rfc4648#section-3.2 (unpadded base64 encoding)
|
|
func FingerprintSHA256(pubKey PublicKey) string {
|
|
sha256sum := sha256.Sum256(pubKey.Marshal())
|
|
hash := base64.RawStdEncoding.EncodeToString(sha256sum[:])
|
|
return "SHA256:" + hash
|
|
}
|