vendor: glide update

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

vendor/golang.org/x/crypto/ssh/keys.go

@@ -10,15 +10,21 @@ import (
 	"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
@@ -29,6 +35,17 @@ const (
 	KeyAlgoECDSA256 = "ecdsa-sha2-nistp256"
 	KeyAlgoECDSA384 = "ecdsa-sha2-nistp384"
 	KeyAlgoECDSA521 = "ecdsa-sha2-nistp521"
+	KeyAlgoED25519  = "ssh-ed25519"
+)
+
+// These constants represent non-default signature algorithms that are supported
+// as algorithm parameters to AlgorithmSigner.SignWithAlgorithm methods. See
+// [PROTOCOL.agent] section 4.5.1 and
+// https://tools.ietf.org/html/draft-ietf-curdle-rsa-sha2-10
+const (
+	SigAlgoRSA        = "ssh-rsa"
+	SigAlgoRSASHA2256 = "rsa-sha2-256"
+	SigAlgoRSASHA2512 = "rsa-sha2-512"
 )
 
 // parsePubKey parses a public key of the given algorithm.
@@ -41,14 +58,16 @@ func parsePubKey(in []byte, algo string) (pubKey PublicKey, rest []byte, err err
 		return parseDSA(in)
 	case KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521:
 		return parseECDSA(in)
-	case CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01:
+	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", err)
+	return nil, nil, fmt.Errorf("ssh: unknown key algorithm: %v", algo)
 }
 
 // parseAuthorizedKey parses a public key in OpenSSH authorized_keys format
@@ -77,6 +96,79 @@ func parseAuthorizedKey(in []byte) (out PublicKey, comment string, err error) {
 	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) {
@@ -194,7 +286,8 @@ type PublicKey interface {
 	Type() string
 
 	// Marshal returns the serialized key data in SSH wire format,
-	// with the name prefix.
+	// 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
@@ -202,6 +295,12 @@ type PublicKey interface {
 	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.
@@ -212,6 +311,19 @@ type Signer interface {
 	Sign(rand io.Reader, data []byte) (*Signature, error)
 }
 
+// A AlgorithmSigner is a Signer that also supports specifying a specific
+// algorithm to use for signing.
+type AlgorithmSigner interface {
+	Signer
+
+	// SignWithAlgorithm is like Signer.Sign, but allows specification of a
+	// non-default signing algorithm. See the SigAlgo* constants in this
+	// package for signature algorithms supported by this package. Callers may
+	// pass an empty string for the algorithm in which case the AlgorithmSigner
+	// will use its default algorithm.
+	SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error)
+}
+
 type rsaPublicKey rsa.PublicKey
 
 func (r *rsaPublicKey) Type() string {
@@ -245,6 +357,8 @@ func parseRSA(in []byte) (out PublicKey, rest []byte, err error) {
 
 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
@@ -258,43 +372,44 @@ func (r *rsaPublicKey) Marshal() []byte {
 }
 
 func (r *rsaPublicKey) Verify(data []byte, sig *Signature) error {
-	if sig.Format != r.Type() {
+	var hash crypto.Hash
+	switch sig.Format {
+	case SigAlgoRSA:
+		hash = crypto.SHA1
+	case SigAlgoRSASHA2256:
+		hash = crypto.SHA256
+	case SigAlgoRSASHA2512:
+		hash = crypto.SHA512
+	default:
 		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, r.Type())
 	}
-	h := crypto.SHA1.New()
+	h := hash.New()
 	h.Write(data)
 	digest := h.Sum(nil)
-	return rsa.VerifyPKCS1v15((*rsa.PublicKey)(r), crypto.SHA1, digest, sig.Blob)
+	return rsa.VerifyPKCS1v15((*rsa.PublicKey)(r), hash, digest, sig.Blob)
 }
 
-type rsaPrivateKey struct {
-	*rsa.PrivateKey
-}
-
-func (r *rsaPrivateKey) PublicKey() PublicKey {
-	return (*rsaPublicKey)(&r.PrivateKey.PublicKey)
-}
-
-func (r *rsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
-	h := crypto.SHA1.New()
-	h.Write(data)
-	digest := h.Sum(nil)
-	blob, err := rsa.SignPKCS1v15(rand, r.PrivateKey, crypto.SHA1, digest)
-	if err != nil {
-		return nil, err
-	}
-	return &Signature{
-		Format: r.PublicKey().Type(),
-		Blob:   blob,
-	}, nil
+func (r *rsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*rsa.PublicKey)(r)
 }
 
 type dsaPublicKey dsa.PublicKey
 
-func (r *dsaPublicKey) Type() string {
+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 {
@@ -305,18 +420,25 @@ func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
 		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: dsa.Parameters{
-			P: w.P,
-			Q: w.Q,
-			G: w.G,
-		},
-		Y: w.Y,
+		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
@@ -355,6 +477,10 @@ func (k *dsaPublicKey) Verify(data []byte, sig *Signature) error {
 	return errors.New("ssh: signature did not verify")
 }
 
+func (k *dsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*dsa.PublicKey)(k)
+}
+
 type dsaPrivateKey struct {
 	*dsa.PrivateKey
 }
@@ -364,6 +490,14 @@ func (k *dsaPrivateKey) PublicKey() PublicKey {
 }
 
 func (k *dsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
+	return k.SignWithAlgorithm(rand, data, "")
+}
+
+func (k *dsaPrivateKey) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error) {
+	if algorithm != "" && algorithm != k.PublicKey().Type() {
+		return nil, fmt.Errorf("ssh: unsupported signature algorithm %s", algorithm)
+	}
+
 	h := crypto.SHA1.New()
 	h.Write(data)
 	digest := h.Sum(nil)
@@ -387,12 +521,12 @@ func (k *dsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
 
 type ecdsaPublicKey ecdsa.PublicKey
 
-func (key *ecdsaPublicKey) Type() string {
-	return "ecdsa-sha2-" + key.nistID()
+func (k *ecdsaPublicKey) Type() string {
+	return "ecdsa-sha2-" + k.nistID()
 }
 
-func (key *ecdsaPublicKey) nistID() string {
-	switch key.Params().BitSize {
+func (k *ecdsaPublicKey) nistID() string {
+	switch k.Params().BitSize {
 	case 256:
 		return "nistp256"
 	case 384:
@@ -403,6 +537,55 @@ func (key *ecdsaPublicKey) nistID() string {
 	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()
 }
@@ -422,14 +605,19 @@ func ecHash(curve elliptic.Curve) crypto.Hash {
 
 // parseECDSA parses an ECDSA key according to RFC 5656, section 3.1.
 func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
-	identifier, in, ok := parseString(in)
-	if !ok {
-		return nil, nil, errShortRead
+	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 string(identifier) {
+	switch w.Curve {
 	case "nistp256":
 		key.Curve = elliptic.P256()
 	case "nistp384":
@@ -440,40 +628,37 @@ func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
 		return nil, nil, errors.New("ssh: unsupported curve")
 	}
 
-	var keyBytes []byte
-	if keyBytes, in, ok = parseString(in); !ok {
-		return nil, nil, errShortRead
-	}
-
-	key.X, key.Y = elliptic.Unmarshal(key.Curve, keyBytes)
+	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), in, nil
+	return (*ecdsaPublicKey)(key), w.Rest, nil
 }
 
-func (key *ecdsaPublicKey) Marshal() []byte {
+func (k *ecdsaPublicKey) Marshal() []byte {
 	// See RFC 5656, section 3.1.
-	keyBytes := elliptic.Marshal(key.Curve, key.X, key.Y)
+	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
 	}{
-		key.Type(),
-		key.nistID(),
+		k.Type(),
+		k.nistID(),
 		keyBytes,
 	}
 
 	return Marshal(&w)
 }
 
-func (key *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
-	if sig.Format != key.Type() {
-		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, key.Type())
+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(key.Curve).New()
+	h := ecHash(k.Curve).New()
 	h.Write(data)
 	digest := h.Sum(nil)
 
@@ -490,78 +675,165 @@ func (key *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
 		return err
 	}
 
-	if ecdsa.Verify((*ecdsa.PublicKey)(key), digest, ecSig.R, ecSig.S) {
+	if ecdsa.Verify((*ecdsa.PublicKey)(k), digest, ecSig.R, ecSig.S) {
 		return nil
 	}
 	return errors.New("ssh: signature did not verify")
 }
 
-type ecdsaPrivateKey struct {
-	*ecdsa.PrivateKey
+func (k *ecdsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*ecdsa.PublicKey)(k)
 }
 
-func (k *ecdsaPrivateKey) PublicKey() PublicKey {
-	return (*ecdsaPublicKey)(&k.PrivateKey.PublicKey)
+// 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 (k *ecdsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
-	h := ecHash(k.PrivateKey.PublicKey.Curve).New()
-	h.Write(data)
-	digest := h.Sum(nil)
-	r, s, err := ecdsa.Sign(rand, k.PrivateKey, digest)
+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
 	}
 
-	sig := make([]byte, intLength(r)+intLength(s))
-	rest := marshalInt(sig, r)
-	marshalInt(rest, s)
+	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: k.PublicKey().Type(),
-		Blob:   sig,
+		Format: algorithm,
+		Blob:   signature,
 	}, nil
 }
 
-// NewSignerFromKey takes a pointer to rsa, dsa or ecdsa PrivateKey
-// returns a corresponding Signer instance. EC keys should use P256,
-// P384 or P521.
-func NewSignerFromKey(k interface{}) (Signer, error) {
-	var sshKey Signer
-	switch t := k.(type) {
-	case *rsa.PrivateKey:
-		sshKey = &rsaPrivateKey{t}
-	case *dsa.PrivateKey:
-		sshKey = &dsaPrivateKey{t}
-	case *ecdsa.PrivateKey:
-		if !supportedEllipticCurve(t.Curve) {
-			return nil, errors.New("ssh: only P256, P384 and P521 EC keys are supported.")
-		}
-
-		sshKey = &ecdsaPrivateKey{t}
-	default:
-		return nil, fmt.Errorf("ssh: unsupported key type %T", k)
-	}
-	return sshKey, nil
-}
-
-// NewPublicKey takes a pointer to rsa, dsa or ecdsa PublicKey
-// and returns a corresponding ssh PublicKey instance. EC keys should use P256, P384 or P521.
-func NewPublicKey(k interface{}) (PublicKey, error) {
-	var sshKey PublicKey
-	switch t := k.(type) {
+// 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:
-		sshKey = (*rsaPublicKey)(t)
+		return (*rsaPublicKey)(key), nil
 	case *ecdsa.PublicKey:
-		if !supportedEllipticCurve(t.Curve) {
-			return nil, errors.New("ssh: only P256, P384 and P521 EC keys are supported.")
+		if !supportedEllipticCurve(key.Curve) {
+			return nil, errors.New("ssh: only P-256, P-384 and P-521 EC keys are supported")
 		}
-		sshKey = (*ecdsaPublicKey)(t)
+		return (*ecdsaPublicKey)(key), nil
 	case *dsa.PublicKey:
-		sshKey = (*dsaPublicKey)(t)
+		return (*dsaPublicKey)(key), nil
+	case ed25519.PublicKey:
+		return (ed25519PublicKey)(key), nil
 	default:
-		return nil, fmt.Errorf("ssh: unsupported key type %T", k)
+		return nil, fmt.Errorf("ssh: unsupported key type %T", key)
 	}
-	return sshKey, nil
 }
 
 // ParsePrivateKey returns a Signer from a PEM encoded private key. It supports
@@ -575,21 +847,87 @@ func ParsePrivateKey(pemBytes []byte) (Signer, error) {
 	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), DSA (OpenSSL), and ECDSA private keys.
+// 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)
 	}
@@ -603,8 +941,8 @@ func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
 		P       *big.Int
 		Q       *big.Int
 		G       *big.Int
-		Priv    *big.Int
 		Pub     *big.Int
+		Priv    *big.Int
 	}
 	rest, err := asn1.Unmarshal(der, &k)
 	if err != nil {
@@ -621,8 +959,142 @@ func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
 				Q: k.Q,
 				G: k.G,
 			},
-			Y: k.Priv,
+			Y: k.Pub,
 		},
-		X: 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
+}