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// 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 ssh
import (
"bytes"
"crypto"
"crypto/dsa"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/md5"
"crypto/rsa"
"crypto/sha256"
"crypto/x509"
"encoding/asn1"
"encoding/base64"
"encoding/hex"
"encoding/pem"
"errors"
"fmt"
"io"
"math/big"
"strings"
"golang.org/x/crypto/ed25519"
)
// These constants represent the algorithm names for key types supported by this
// package.
const (
KeyAlgoRSA = "ssh-rsa"
KeyAlgoDSA = "ssh-dss"
KeyAlgoECDSA256 = "ecdsa-sha2-nistp256"
KeyAlgoECDSA384 = "ecdsa-sha2-nistp384"
KeyAlgoECDSA521 = "ecdsa-sha2-nistp521"
KeyAlgoED25519 = "ssh-ed25519"
)
// parsePubKey parses a public key of the given algorithm.
// Use ParsePublicKey for keys with prepended algorithm.
func parsePubKey(in []byte, algo string) (pubKey PublicKey, rest []byte, err error) {
switch algo {
case KeyAlgoRSA:
return parseRSA(in)
case KeyAlgoDSA:
return parseDSA(in)
case KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521:
return parseECDSA(in)
case KeyAlgoED25519:
return parseED25519(in)
case CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01, CertAlgoED25519v01:
cert, err := parseCert(in, certToPrivAlgo(algo))
if err != nil {
return nil, nil, err
}
return cert, nil, nil
}
return nil, nil, fmt.Errorf("ssh: unknown key algorithm: %v", algo)
}
// parseAuthorizedKey parses a public key in OpenSSH authorized_keys format
// (see sshd(8) manual page) once the options and key type fields have been
// removed.
func parseAuthorizedKey(in []byte) (out PublicKey, comment string, err error) {
in = bytes.TrimSpace(in)
i := bytes.IndexAny(in, " \t")
if i == -1 {
i = len(in)
}
base64Key := in[:i]
key := make([]byte, base64.StdEncoding.DecodedLen(len(base64Key)))
n, err := base64.StdEncoding.Decode(key, base64Key)
if err != nil {
return nil, "", err
}
key = key[:n]
out, err = ParsePublicKey(key)
if err != nil {
return nil, "", err
}
comment = string(bytes.TrimSpace(in[i:]))
return out, comment, nil
}
// ParseKnownHosts parses an entry in the format of the known_hosts file.
//
// The known_hosts format is documented in the sshd(8) manual page. This
// function will parse a single entry from in. On successful return, marker
// will contain the optional marker value (i.e. "cert-authority" or "revoked")
// or else be empty, hosts will contain the hosts that this entry matches,
// pubKey will contain the public key and comment will contain any trailing
// comment at the end of the line. See the sshd(8) manual page for the various
// forms that a host string can take.
//
// The unparsed remainder of the input will be returned in rest. This function
// can be called repeatedly to parse multiple entries.
//
// If no entries were found in the input then err will be io.EOF. Otherwise a
// non-nil err value indicates a parse error.
func ParseKnownHosts(in []byte) (marker string, hosts []string, pubKey PublicKey, comment string, rest []byte, err error) {
for len(in) > 0 {
end := bytes.IndexByte(in, '\n')
if end != -1 {
rest = in[end+1:]
in = in[:end]
} else {
rest = nil
}
end = bytes.IndexByte(in, '\r')
if end != -1 {
in = in[:end]
}
in = bytes.TrimSpace(in)
if len(in) == 0 || in[0] == '#' {
in = rest
continue
}
i := bytes.IndexAny(in, " \t")
if i == -1 {
in = rest
continue
}
// Strip out the beginning of the known_host key.
// This is either an optional marker or a (set of) hostname(s).
keyFields := bytes.Fields(in)
if len(keyFields) < 3 || len(keyFields) > 5 {
return "", nil, nil, "", nil, errors.New("ssh: invalid entry in known_hosts data")
}
// keyFields[0] is either "@cert-authority", "@revoked" or a comma separated
// list of hosts
marker := ""
if keyFields[0][0] == '@' {
marker = string(keyFields[0][1:])
keyFields = keyFields[1:]
}
hosts := string(keyFields[0])
// keyFields[1] contains the key type (e.g. “ssh-rsa”).
// However, that information is duplicated inside the
// base64-encoded key and so is ignored here.
key := bytes.Join(keyFields[2:], []byte(" "))
if pubKey, comment, err = parseAuthorizedKey(key); err != nil {
return "", nil, nil, "", nil, err
}
return marker, strings.Split(hosts, ","), pubKey, comment, rest, nil
}
return "", nil, nil, "", nil, io.EOF
}
// ParseAuthorizedKeys parses a public key from an authorized_keys
// file used in OpenSSH according to the sshd(8) manual page.
func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []string, rest []byte, err error) {
for len(in) > 0 {
end := bytes.IndexByte(in, '\n')
if end != -1 {
rest = in[end+1:]
in = in[:end]
} else {
rest = nil
}
end = bytes.IndexByte(in, '\r')
if end != -1 {
in = in[:end]
}
in = bytes.TrimSpace(in)
if len(in) == 0 || in[0] == '#' {
in = rest
continue
}
i := bytes.IndexAny(in, " \t")
if i == -1 {
in = rest
continue
}
if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
return out, comment, options, rest, nil
}
// No key type recognised. Maybe there's an options field at
// the beginning.
var b byte
inQuote := false
var candidateOptions []string
optionStart := 0
for i, b = range in {
isEnd := !inQuote && (b == ' ' || b == '\t')
if (b == ',' && !inQuote) || isEnd {
if i-optionStart > 0 {
candidateOptions = append(candidateOptions, string(in[optionStart:i]))
}
optionStart = i + 1
}
if isEnd {
break
}
if b == '"' && (i == 0 || (i > 0 && in[i-1] != '\\')) {
inQuote = !inQuote
}
}
for i < len(in) && (in[i] == ' ' || in[i] == '\t') {
i++
}
if i == len(in) {
// Invalid line: unmatched quote
in = rest
continue
}
in = in[i:]
i = bytes.IndexAny(in, " \t")
if i == -1 {
in = rest
continue
}
if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
options = candidateOptions
return out, comment, options, rest, nil
}
in = rest
continue
}
return nil, "", nil, nil, errors.New("ssh: no key found")
}
// ParsePublicKey parses an SSH public key formatted for use in
// the SSH wire protocol according to RFC 4253, section 6.6.
func ParsePublicKey(in []byte) (out PublicKey, err error) {
algo, in, ok := parseString(in)
if !ok {
return nil, errShortRead
}
var rest []byte
out, rest, err = parsePubKey(in, string(algo))
if len(rest) > 0 {
return nil, errors.New("ssh: trailing junk in public key")
}
return out, err
}
// MarshalAuthorizedKey serializes key for inclusion in an OpenSSH
// authorized_keys file. The return value ends with newline.
func MarshalAuthorizedKey(key PublicKey) []byte {
b := &bytes.Buffer{}
b.WriteString(key.Type())
b.WriteByte(' ')
e := base64.NewEncoder(base64.StdEncoding, b)
e.Write(key.Marshal())
e.Close()
b.WriteByte('\n')
return b.Bytes()
}
// PublicKey is an abstraction of different types of public keys.
type PublicKey interface {
// Type returns the key's type, e.g. "ssh-rsa".
Type() string
// Marshal returns the serialized key data in SSH wire format,
// with the name prefix. To unmarshal the returned data, use
// the ParsePublicKey function.
Marshal() []byte
// Verify that sig is a signature on the given data using this
// key. This function will hash the data appropriately first.
Verify(data []byte, sig *Signature) error
}
// CryptoPublicKey, if implemented by a PublicKey,
// returns the underlying crypto.PublicKey form of the key.
type CryptoPublicKey interface {
CryptoPublicKey() crypto.PublicKey
}
// A Signer can create signatures that verify against a public key.
type Signer interface {
// PublicKey returns an associated PublicKey instance.
PublicKey() PublicKey
// Sign returns raw signature for the given data. This method
// will apply the hash specified for the keytype to the data.
Sign(rand io.Reader, data []byte) (*Signature, error)
}
type rsaPublicKey rsa.PublicKey
func (r *rsaPublicKey) Type() string {
return "ssh-rsa"
}
// parseRSA parses an RSA key according to RFC 4253, section 6.6.
func parseRSA(in []byte) (out PublicKey, rest []byte, err error) {
var w struct {
E *big.Int
N *big.Int
Rest []byte `ssh:"rest"`
}
if err := Unmarshal(in, &w); err != nil {
return nil, nil, err
}
if w.E.BitLen() > 24 {
return nil, nil, errors.New("ssh: exponent too large")
}
e := w.E.Int64()
if e < 3 || e&1 == 0 {
return nil, nil, errors.New("ssh: incorrect exponent")
}
var key rsa.PublicKey
key.E = int(e)
key.N = w.N
return (*rsaPublicKey)(&key), w.Rest, nil
}
func (r *rsaPublicKey) Marshal() []byte {
e := new(big.Int).SetInt64(int64(r.E))
// RSA publickey struct layout should match the struct used by
// parseRSACert in the x/crypto/ssh/agent package.
wirekey := struct {
Name string
E *big.Int
N *big.Int
}{
KeyAlgoRSA,
e,
r.N,
}
return Marshal(&wirekey)
}
func (r *rsaPublicKey) Verify(data []byte, sig *Signature) error {
if sig.Format != r.Type() {
return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, r.Type())
}
h := crypto.SHA1.New()
h.Write(data)
digest := h.Sum(nil)
return rsa.VerifyPKCS1v15((*rsa.PublicKey)(r), crypto.SHA1, digest, sig.Blob)
}
func (r *rsaPublicKey) CryptoPublicKey() crypto.PublicKey {
return (*rsa.PublicKey)(r)
}
type dsaPublicKey dsa.PublicKey
func (k *dsaPublicKey) Type() string {
return "ssh-dss"
}
func checkDSAParams(param *dsa.Parameters) error {
// SSH specifies FIPS 186-2, which only provided a single size
// (1024 bits) DSA key. FIPS 186-3 allows for larger key
// sizes, which would confuse SSH.
if l := param.P.BitLen(); l != 1024 {
return fmt.Errorf("ssh: unsupported DSA key size %d", l)
}
return nil
}
// parseDSA parses an DSA key according to RFC 4253, section 6.6.
func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
var w struct {
P, Q, G, Y *big.Int
Rest []byte `ssh:"rest"`
}
if err := Unmarshal(in, &w); err != nil {
return nil, nil, err
}
param := dsa.Parameters{
P: w.P,
Q: w.Q,
G: w.G,
}
if err := checkDSAParams(&param); err != nil {
return nil, nil, err
}
key := &dsaPublicKey{
Parameters: param,
Y: w.Y,
}
return key, w.Rest, nil
}
func (k *dsaPublicKey) Marshal() []byte {
// DSA publickey struct layout should match the struct used by
// parseDSACert in the x/crypto/ssh/agent package.
w := struct {
Name string
P, Q, G, Y *big.Int
}{
k.Type(),
k.P,
k.Q,
k.G,
k.Y,
}
return Marshal(&w)
}
func (k *dsaPublicKey) 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 := crypto.SHA1.New()
h.Write(data)
digest := h.Sum(nil)
// Per RFC 4253, section 6.6,
// The value for 'dss_signature_blob' is encoded as a string containing
// r, followed by s (which are 160-bit integers, without lengths or
// padding, unsigned, and in network byte order).
// For DSS purposes, sig.Blob should be exactly 40 bytes in length.
if len(sig.Blob) != 40 {
return errors.New("ssh: DSA signature parse error")
}
r := new(big.Int).SetBytes(sig.Blob[:20])
s := new(big.Int).SetBytes(sig.Blob[20:])
if dsa.Verify((*dsa.PublicKey)(k), digest, r, s) {
return nil
}
return errors.New("ssh: signature did not verify")
}
func (k *dsaPublicKey) CryptoPublicKey() crypto.PublicKey {
return (*dsa.PublicKey)(k)
}
type dsaPrivateKey struct {
*dsa.PrivateKey
}
func (k *dsaPrivateKey) PublicKey() PublicKey {
return (*dsaPublicKey)(&k.PrivateKey.PublicKey)
}
func (k *dsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
h := crypto.SHA1.New()
h.Write(data)
digest := h.Sum(nil)
r, s, err := dsa.Sign(rand, k.PrivateKey, digest)
if err != nil {
return nil, err
}
sig := make([]byte, 40)
rb := r.Bytes()
sb := s.Bytes()
copy(sig[20-len(rb):20], rb)
copy(sig[40-len(sb):], sb)
return &Signature{
Format: k.PublicKey().Type(),
Blob: sig,
}, nil
}
type ecdsaPublicKey ecdsa.PublicKey
func (k *ecdsaPublicKey) Type() string {
return "ecdsa-sha2-" + k.nistID()
}
func (k *ecdsaPublicKey) nistID() string {
switch k.Params().BitSize {
case 256:
return "nistp256"
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) {
var hashFunc crypto.Hash
switch key := s.pubKey.(type) {
case *rsaPublicKey, *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: s.pubKey.Type(),
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
}