forked from mystiq/dex
628 lines
15 KiB
Go
628 lines
15 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/rsa"
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"crypto/x509"
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"encoding/asn1"
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"encoding/base64"
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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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)
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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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)
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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 CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01:
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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", err)
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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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// 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.
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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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// 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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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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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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if sig.Format != r.Type() {
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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 := crypto.SHA1.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), crypto.SHA1, digest, sig.Blob)
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}
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type rsaPrivateKey struct {
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*rsa.PrivateKey
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}
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func (r *rsaPrivateKey) PublicKey() PublicKey {
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return (*rsaPublicKey)(&r.PrivateKey.PublicKey)
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}
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func (r *rsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
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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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blob, err := rsa.SignPKCS1v15(rand, r.PrivateKey, crypto.SHA1, digest)
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if err != nil {
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return nil, err
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}
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return &Signature{
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Format: r.PublicKey().Type(),
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Blob: blob,
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}, nil
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}
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type dsaPublicKey dsa.PublicKey
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func (r *dsaPublicKey) Type() string {
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return "ssh-dss"
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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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key := &dsaPublicKey{
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Parameters: 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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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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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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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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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 (key *ecdsaPublicKey) Type() string {
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return "ecdsa-sha2-" + key.nistID()
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}
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func (key *ecdsaPublicKey) nistID() string {
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switch key.Params().BitSize {
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case 256:
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return "nistp256"
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case 384:
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return "nistp384"
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case 521:
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return "nistp521"
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}
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panic("ssh: unsupported ecdsa key size")
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}
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func supportedEllipticCurve(curve elliptic.Curve) bool {
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return curve == elliptic.P256() || curve == elliptic.P384() || curve == elliptic.P521()
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}
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// ecHash returns the hash to match the given elliptic curve, see RFC
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// 5656, section 6.2.1
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func ecHash(curve elliptic.Curve) crypto.Hash {
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bitSize := curve.Params().BitSize
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switch {
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case bitSize <= 256:
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return crypto.SHA256
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case bitSize <= 384:
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return crypto.SHA384
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}
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return crypto.SHA512
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}
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// parseECDSA parses an ECDSA key according to RFC 5656, section 3.1.
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func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
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identifier, in, ok := parseString(in)
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if !ok {
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return nil, nil, errShortRead
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}
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key := new(ecdsa.PublicKey)
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switch string(identifier) {
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case "nistp256":
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key.Curve = elliptic.P256()
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case "nistp384":
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key.Curve = elliptic.P384()
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case "nistp521":
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key.Curve = elliptic.P521()
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default:
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return nil, nil, errors.New("ssh: unsupported curve")
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}
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var keyBytes []byte
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if keyBytes, in, ok = parseString(in); !ok {
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return nil, nil, errShortRead
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}
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key.X, key.Y = elliptic.Unmarshal(key.Curve, keyBytes)
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if key.X == nil || key.Y == nil {
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return nil, nil, errors.New("ssh: invalid curve point")
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}
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return (*ecdsaPublicKey)(key), in, nil
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}
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func (key *ecdsaPublicKey) Marshal() []byte {
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// See RFC 5656, section 3.1.
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keyBytes := elliptic.Marshal(key.Curve, key.X, key.Y)
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w := struct {
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Name string
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ID string
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Key []byte
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}{
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key.Type(),
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key.nistID(),
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keyBytes,
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}
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return Marshal(&w)
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}
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func (key *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
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if sig.Format != key.Type() {
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return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, key.Type())
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}
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h := ecHash(key.Curve).New()
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h.Write(data)
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digest := h.Sum(nil)
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// Per RFC 5656, section 3.1.2,
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// The ecdsa_signature_blob value has the following specific encoding:
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// mpint r
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// mpint s
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var ecSig struct {
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R *big.Int
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S *big.Int
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}
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if err := Unmarshal(sig.Blob, &ecSig); err != nil {
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return err
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}
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if ecdsa.Verify((*ecdsa.PublicKey)(key), digest, ecSig.R, ecSig.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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type ecdsaPrivateKey struct {
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*ecdsa.PrivateKey
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}
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func (k *ecdsaPrivateKey) PublicKey() PublicKey {
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return (*ecdsaPublicKey)(&k.PrivateKey.PublicKey)
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}
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func (k *ecdsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
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h := ecHash(k.PrivateKey.PublicKey.Curve).New()
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h.Write(data)
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digest := h.Sum(nil)
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r, s, err := ecdsa.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, intLength(r)+intLength(s))
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rest := marshalInt(sig, r)
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marshalInt(rest, s)
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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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// NewSignerFromKey takes a pointer to rsa, dsa or ecdsa PrivateKey
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// returns a corresponding Signer instance. EC keys should use P256,
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// P384 or P521.
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func NewSignerFromKey(k interface{}) (Signer, error) {
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var sshKey Signer
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switch t := k.(type) {
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case *rsa.PrivateKey:
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sshKey = &rsaPrivateKey{t}
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case *dsa.PrivateKey:
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sshKey = &dsaPrivateKey{t}
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case *ecdsa.PrivateKey:
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if !supportedEllipticCurve(t.Curve) {
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return nil, errors.New("ssh: only P256, P384 and P521 EC keys are supported.")
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}
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sshKey = &ecdsaPrivateKey{t}
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default:
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return nil, fmt.Errorf("ssh: unsupported key type %T", k)
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}
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return sshKey, nil
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}
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|
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// 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) {
|
|
case *rsa.PublicKey:
|
|
sshKey = (*rsaPublicKey)(t)
|
|
case *ecdsa.PublicKey:
|
|
if !supportedEllipticCurve(t.Curve) {
|
|
return nil, errors.New("ssh: only P256, P384 and P521 EC keys are supported.")
|
|
}
|
|
sshKey = (*ecdsaPublicKey)(t)
|
|
case *dsa.PublicKey:
|
|
sshKey = (*dsaPublicKey)(t)
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %T", k)
|
|
}
|
|
return sshKey, nil
|
|
}
|
|
|
|
// 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)
|
|
}
|
|
|
|
// ParseRawPrivateKey returns a private key from a PEM encoded private key. It
|
|
// supports RSA (PKCS#1), 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")
|
|
}
|
|
|
|
switch block.Type {
|
|
case "RSA PRIVATE KEY":
|
|
return x509.ParsePKCS1PrivateKey(block.Bytes)
|
|
case "EC PRIVATE KEY":
|
|
return x509.ParseECPrivateKey(block.Bytes)
|
|
case "DSA PRIVATE KEY":
|
|
return ParseDSAPrivateKey(block.Bytes)
|
|
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
|
|
Priv *big.Int
|
|
Pub *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.Priv,
|
|
},
|
|
X: k.Pub,
|
|
}, nil
|
|
}
|