565 lines
14 KiB
Go
565 lines
14 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package packet
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import (
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"bytes"
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"crypto/cipher"
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"crypto/dsa"
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"crypto/ecdsa"
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"crypto/sha1"
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"fmt"
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"io"
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"io/ioutil"
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"math/big"
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"strconv"
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"time"
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"github.com/keybase/go-crypto/ed25519"
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"github.com/keybase/go-crypto/openpgp/ecdh"
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"github.com/keybase/go-crypto/openpgp/elgamal"
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"github.com/keybase/go-crypto/openpgp/errors"
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"github.com/keybase/go-crypto/openpgp/s2k"
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"github.com/keybase/go-crypto/rsa"
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)
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// PrivateKey represents a possibly encrypted private key. See RFC 4880,
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// section 5.5.3.
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type PrivateKey struct {
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PublicKey
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Encrypted bool // if true then the private key is unavailable until Decrypt has been called.
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encryptedData []byte
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cipher CipherFunction
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s2k func(out, in []byte)
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PrivateKey interface{} // An *rsa.PrivateKey or *dsa.PrivateKey.
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sha1Checksum bool
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iv []byte
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s2kHeader []byte
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}
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type EdDSAPrivateKey struct {
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PrivateKey
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seed parsedMPI
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}
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func (e *EdDSAPrivateKey) Seed() []byte {
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return e.seed.bytes
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}
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func (e *EdDSAPrivateKey) Sign(digest []byte) (R, S []byte, err error) {
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r := bytes.NewReader(e.seed.bytes)
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publicKey, privateKey, err := ed25519.GenerateKey(r)
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if err != nil {
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return nil, nil, err
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}
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if !bytes.Equal(publicKey, e.PublicKey.edk.p.bytes[1:]) { // [1:] because [0] is 0x40 mpi header
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return nil, nil, errors.UnsupportedError("EdDSA: Private key does not match public key.")
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}
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sig := ed25519.Sign(privateKey, digest)
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sigLen := ed25519.SignatureSize / 2
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return sig[:sigLen], sig[sigLen:], nil
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}
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func NewRSAPrivateKey(currentTime time.Time, priv *rsa.PrivateKey) *PrivateKey {
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pk := new(PrivateKey)
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pk.PublicKey = *NewRSAPublicKey(currentTime, &priv.PublicKey)
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pk.PrivateKey = priv
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return pk
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}
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func NewDSAPrivateKey(currentTime time.Time, priv *dsa.PrivateKey) *PrivateKey {
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pk := new(PrivateKey)
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pk.PublicKey = *NewDSAPublicKey(currentTime, &priv.PublicKey)
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pk.PrivateKey = priv
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return pk
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}
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func NewElGamalPrivateKey(currentTime time.Time, priv *elgamal.PrivateKey) *PrivateKey {
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pk := new(PrivateKey)
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pk.PublicKey = *NewElGamalPublicKey(currentTime, &priv.PublicKey)
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pk.PrivateKey = priv
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return pk
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}
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func NewECDSAPrivateKey(currentTime time.Time, priv *ecdsa.PrivateKey) *PrivateKey {
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pk := new(PrivateKey)
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pk.PublicKey = *NewECDSAPublicKey(currentTime, &priv.PublicKey)
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pk.PrivateKey = priv
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return pk
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}
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func NewECDHPrivateKey(currentTime time.Time, priv *ecdh.PrivateKey) *PrivateKey {
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pk := new(PrivateKey)
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pk.PublicKey = *NewECDHPublicKey(currentTime, &priv.PublicKey)
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pk.PrivateKey = priv
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return pk
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}
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func (pk *PrivateKey) parse(r io.Reader) (err error) {
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err = (&pk.PublicKey).parse(r)
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if err != nil {
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return
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}
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var buf [1]byte
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_, err = readFull(r, buf[:])
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if err != nil {
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return
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}
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s2kType := buf[0]
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switch s2kType {
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case 0:
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pk.s2k = nil
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pk.Encrypted = false
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case 254, 255:
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_, err = readFull(r, buf[:])
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if err != nil {
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return
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}
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pk.cipher = CipherFunction(buf[0])
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pk.Encrypted = true
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pk.s2k, err = s2k.Parse(r)
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if err != nil {
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return
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}
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if s2kType == 254 {
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pk.sha1Checksum = true
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}
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// S2K == nil implies that we got a "GNU Dummy" S2K. For instance,
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// because our master secret key is on a USB key in a vault somewhere.
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// In that case, there is no further data to consume here.
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if pk.s2k == nil {
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pk.Encrypted = false
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return
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}
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default:
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return errors.UnsupportedError("deprecated s2k function in private key")
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}
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if pk.Encrypted {
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blockSize := pk.cipher.blockSize()
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if blockSize == 0 {
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return errors.UnsupportedError("unsupported cipher in private key: " + strconv.Itoa(int(pk.cipher)))
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}
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pk.iv = make([]byte, blockSize)
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_, err = readFull(r, pk.iv)
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if err != nil {
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return
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}
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}
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pk.encryptedData, err = ioutil.ReadAll(r)
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if err != nil {
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return
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}
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if !pk.Encrypted {
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return pk.parsePrivateKey(pk.encryptedData)
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}
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return
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}
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func mod64kHash(d []byte) uint16 {
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var h uint16
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for _, b := range d {
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h += uint16(b)
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}
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return h
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}
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// Encrypt is the counterpart to the Decrypt() method below. It encrypts
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// the private key with the provided passphrase. If config is nil, then
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// the standard, and sensible, defaults apply.
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//
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// A key will be derived from the given passphrase using S2K Specifier
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// Type 3 (Iterated + Salted, see RFC-4880 Sec. 3.7.1.3). This choice
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// is hardcoded in s2k.Serialize(). S2KCount is hardcoded to 0, which is
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// equivalent to 65536. And the hash algorithm for key-derivation can be
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// set with config. The encrypted PrivateKey, using the algorithm specified
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// in config (if provided), is written out to the encryptedData member.
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// When Serialize() is called, this encryptedData member will be
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// serialized, using S2K Usage value of 254, and thus SHA1 checksum.
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func (pk *PrivateKey) Encrypt(passphrase []byte, config *Config) (err error) {
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if pk.PrivateKey == nil {
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return errors.InvalidArgumentError("there is no private key to encrypt")
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}
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pk.sha1Checksum = true
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pk.cipher = config.Cipher()
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s2kConfig := s2k.Config{
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Hash: config.Hash(),
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S2KCount: 0,
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}
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s2kBuf := bytes.NewBuffer(nil)
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derivedKey := make([]byte, pk.cipher.KeySize())
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err = s2k.Serialize(s2kBuf, derivedKey, config.Random(), passphrase, &s2kConfig)
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if err != nil {
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return err
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}
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pk.s2kHeader = s2kBuf.Bytes()
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// No good way to set pk.s2k but to call s2k.Parse(),
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// even though we have all the information here, but
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// most of the functions needed are private to s2k.
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pk.s2k, err = s2k.Parse(s2kBuf)
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pk.iv = make([]byte, pk.cipher.blockSize())
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if _, err = config.Random().Read(pk.iv); err != nil {
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return err
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}
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privateKeyBuf := bytes.NewBuffer(nil)
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if err = pk.serializePrivateKey(privateKeyBuf); err != nil {
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return err
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}
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checksum := sha1.Sum(privateKeyBuf.Bytes())
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if _, err = privateKeyBuf.Write(checksum[:]); err != nil {
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return err
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}
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pkData := privateKeyBuf.Bytes()
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block := pk.cipher.new(derivedKey)
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pk.encryptedData = make([]byte, len(pkData))
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cfb := cipher.NewCFBEncrypter(block, pk.iv)
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cfb.XORKeyStream(pk.encryptedData, pkData)
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pk.Encrypted = true
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return nil
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}
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func (pk *PrivateKey) Serialize(w io.Writer) (err error) {
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buf := bytes.NewBuffer(nil)
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err = pk.PublicKey.serializeWithoutHeaders(buf)
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if err != nil {
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return
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}
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privateKeyBuf := bytes.NewBuffer(nil)
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if pk.PrivateKey == nil {
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_, err = buf.Write([]byte{
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254, // SHA-1 Convention
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9, // Encryption scheme (AES256)
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101, // GNU Extensions
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2, // Hash value (SHA1)
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'G', 'N', 'U', // "GNU" as a string
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1, // Extension type 1001 (minus 1000)
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})
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} else if pk.Encrypted {
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_, err = buf.Write([]byte{
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254, // SHA-1 Convention
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byte(pk.cipher), // Encryption scheme
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})
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if err != nil {
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return err
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}
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if _, err = buf.Write(pk.s2kHeader); err != nil {
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return err
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}
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if _, err = buf.Write(pk.iv); err != nil {
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return err
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}
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if _, err = privateKeyBuf.Write(pk.encryptedData); err != nil {
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return err
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}
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} else {
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buf.WriteByte(0 /* no encryption */)
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if err = pk.serializePrivateKey(privateKeyBuf); err != nil {
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return err
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}
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}
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ptype := packetTypePrivateKey
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contents := buf.Bytes()
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privateKeyBytes := privateKeyBuf.Bytes()
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if pk.IsSubkey {
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ptype = packetTypePrivateSubkey
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}
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totalLen := len(contents) + len(privateKeyBytes)
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if !pk.Encrypted {
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totalLen += 2
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}
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err = serializeHeader(w, ptype, totalLen)
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if err != nil {
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return
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}
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_, err = w.Write(contents)
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if err != nil {
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return
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}
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_, err = w.Write(privateKeyBytes)
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if err != nil {
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return
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}
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if len(privateKeyBytes) > 0 && !pk.Encrypted {
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checksum := mod64kHash(privateKeyBytes)
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var checksumBytes [2]byte
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checksumBytes[0] = byte(checksum >> 8)
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checksumBytes[1] = byte(checksum)
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_, err = w.Write(checksumBytes[:])
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}
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return
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}
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func (pk *PrivateKey) serializePrivateKey(w io.Writer) (err error) {
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switch priv := pk.PrivateKey.(type) {
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case *rsa.PrivateKey:
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err = serializeRSAPrivateKey(w, priv)
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case *dsa.PrivateKey:
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err = serializeDSAPrivateKey(w, priv)
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case *elgamal.PrivateKey:
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err = serializeElGamalPrivateKey(w, priv)
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case *ecdsa.PrivateKey:
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err = serializeECDSAPrivateKey(w, priv)
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case *ecdh.PrivateKey:
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err = serializeECDHPrivateKey(w, priv)
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case *EdDSAPrivateKey:
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err = serializeEdDSAPrivateKey(w, priv)
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default:
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err = errors.InvalidArgumentError("unknown private key type")
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}
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return err
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}
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func serializeRSAPrivateKey(w io.Writer, priv *rsa.PrivateKey) error {
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err := writeBig(w, priv.D)
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if err != nil {
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return err
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}
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err = writeBig(w, priv.Primes[1])
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if err != nil {
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return err
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}
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err = writeBig(w, priv.Primes[0])
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if err != nil {
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return err
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}
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return writeBig(w, priv.Precomputed.Qinv)
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}
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func serializeDSAPrivateKey(w io.Writer, priv *dsa.PrivateKey) error {
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return writeBig(w, priv.X)
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}
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func serializeElGamalPrivateKey(w io.Writer, priv *elgamal.PrivateKey) error {
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return writeBig(w, priv.X)
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}
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func serializeECDSAPrivateKey(w io.Writer, priv *ecdsa.PrivateKey) error {
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return writeBig(w, priv.D)
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}
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func serializeECDHPrivateKey(w io.Writer, priv *ecdh.PrivateKey) error {
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return writeBig(w, priv.X)
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}
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func serializeEdDSAPrivateKey(w io.Writer, priv *EdDSAPrivateKey) error {
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return writeMPI(w, priv.seed.bitLength, priv.seed.bytes)
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}
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// Decrypt decrypts an encrypted private key using a passphrase.
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func (pk *PrivateKey) Decrypt(passphrase []byte) error {
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if !pk.Encrypted {
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return nil
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}
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// For GNU Dummy S2K, there's no key here, so don't do anything.
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if pk.s2k == nil {
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return nil
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}
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key := make([]byte, pk.cipher.KeySize())
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pk.s2k(key, passphrase)
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block := pk.cipher.new(key)
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cfb := cipher.NewCFBDecrypter(block, pk.iv)
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data := make([]byte, len(pk.encryptedData))
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cfb.XORKeyStream(data, pk.encryptedData)
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if pk.sha1Checksum {
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if len(data) < sha1.Size {
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return errors.StructuralError("truncated private key data")
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}
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h := sha1.New()
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h.Write(data[:len(data)-sha1.Size])
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sum := h.Sum(nil)
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if !bytes.Equal(sum, data[len(data)-sha1.Size:]) {
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return errors.StructuralError("private key checksum failure")
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}
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data = data[:len(data)-sha1.Size]
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} else {
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if len(data) < 2 {
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return errors.StructuralError("truncated private key data")
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}
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var sum uint16
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for i := 0; i < len(data)-2; i++ {
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sum += uint16(data[i])
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}
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if data[len(data)-2] != uint8(sum>>8) ||
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data[len(data)-1] != uint8(sum) {
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return errors.StructuralError("private key checksum failure")
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}
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data = data[:len(data)-2]
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}
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return pk.parsePrivateKey(data)
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}
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func (pk *PrivateKey) parsePrivateKey(data []byte) (err error) {
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switch pk.PublicKey.PubKeyAlgo {
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case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly, PubKeyAlgoRSAEncryptOnly:
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return pk.parseRSAPrivateKey(data)
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case PubKeyAlgoDSA:
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return pk.parseDSAPrivateKey(data)
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case PubKeyAlgoElGamal:
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return pk.parseElGamalPrivateKey(data)
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case PubKeyAlgoECDSA:
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return pk.parseECDSAPrivateKey(data)
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case PubKeyAlgoECDH:
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return pk.parseECDHPrivateKey(data)
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case PubKeyAlgoEdDSA:
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return pk.parseEdDSAPrivateKey(data)
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case PubKeyAlgoBadElGamal:
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return errors.UnsupportedError("parsing el-gamal sign-or-encrypt privatekeys is unsupported")
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default:
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return errors.UnsupportedError("cannot parse this private key type")
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}
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}
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func (pk *PrivateKey) parseRSAPrivateKey(data []byte) (err error) {
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rsaPub := pk.PublicKey.PublicKey.(*rsa.PublicKey)
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rsaPriv := new(rsa.PrivateKey)
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rsaPriv.PublicKey = *rsaPub
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buf := bytes.NewBuffer(data)
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d, _, err := readMPI(buf)
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if err != nil {
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return
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}
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p, _, err := readMPI(buf)
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if err != nil {
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return
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}
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q, _, err := readMPI(buf)
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if err != nil {
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return
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}
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rsaPriv.D = new(big.Int).SetBytes(d)
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rsaPriv.Primes = make([]*big.Int, 2)
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rsaPriv.Primes[0] = new(big.Int).SetBytes(p)
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rsaPriv.Primes[1] = new(big.Int).SetBytes(q)
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if err := rsaPriv.Validate(); err != nil {
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return err
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}
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rsaPriv.Precompute()
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pk.PrivateKey = rsaPriv
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pk.Encrypted = false
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pk.encryptedData = nil
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return nil
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}
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func (pk *PrivateKey) parseDSAPrivateKey(data []byte) (err error) {
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dsaPub := pk.PublicKey.PublicKey.(*dsa.PublicKey)
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dsaPriv := new(dsa.PrivateKey)
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dsaPriv.PublicKey = *dsaPub
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buf := bytes.NewBuffer(data)
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x, _, err := readMPI(buf)
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if err != nil {
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return
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}
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dsaPriv.X = new(big.Int).SetBytes(x)
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pk.PrivateKey = dsaPriv
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pk.Encrypted = false
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pk.encryptedData = nil
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return nil
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}
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func (pk *PrivateKey) parseElGamalPrivateKey(data []byte) (err error) {
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pub := pk.PublicKey.PublicKey.(*elgamal.PublicKey)
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priv := new(elgamal.PrivateKey)
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priv.PublicKey = *pub
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buf := bytes.NewBuffer(data)
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x, _, err := readMPI(buf)
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if err != nil {
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return
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}
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priv.X = new(big.Int).SetBytes(x)
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pk.PrivateKey = priv
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pk.Encrypted = false
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pk.encryptedData = nil
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return nil
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}
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func (pk *PrivateKey) parseECDHPrivateKey(data []byte) (err error) {
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pub := pk.PublicKey.PublicKey.(*ecdh.PublicKey)
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priv := new(ecdh.PrivateKey)
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priv.PublicKey = *pub
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buf := bytes.NewBuffer(data)
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d, _, err := readMPI(buf)
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if err != nil {
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return
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}
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priv.X = new(big.Int).SetBytes(d)
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pk.PrivateKey = priv
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pk.Encrypted = false
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pk.encryptedData = nil
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return nil
|
|
}
|
|
|
|
func (pk *PrivateKey) parseECDSAPrivateKey(data []byte) (err error) {
|
|
ecdsaPub := pk.PublicKey.PublicKey.(*ecdsa.PublicKey)
|
|
ecdsaPriv := new(ecdsa.PrivateKey)
|
|
ecdsaPriv.PublicKey = *ecdsaPub
|
|
|
|
buf := bytes.NewBuffer(data)
|
|
d, _, err := readMPI(buf)
|
|
if err != nil {
|
|
return
|
|
}
|
|
|
|
ecdsaPriv.D = new(big.Int).SetBytes(d)
|
|
pk.PrivateKey = ecdsaPriv
|
|
pk.Encrypted = false
|
|
pk.encryptedData = nil
|
|
|
|
return nil
|
|
}
|
|
|
|
func (pk *PrivateKey) parseEdDSAPrivateKey(data []byte) (err error) {
|
|
eddsaPriv := new(EdDSAPrivateKey)
|
|
eddsaPriv.PublicKey = pk.PublicKey
|
|
|
|
buf := bytes.NewBuffer(data)
|
|
eddsaPriv.seed.bytes, eddsaPriv.seed.bitLength, err = readMPI(buf)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
if bLen := len(eddsaPriv.seed.bytes); bLen != 32 { // 32 bytes private part of ed25519 key.
|
|
return errors.UnsupportedError(fmt.Sprintf("Unexpected EdDSA private key length: %d", bLen))
|
|
}
|
|
|
|
pk.PrivateKey = eddsaPriv
|
|
pk.Encrypted = false
|
|
pk.encryptedData = nil
|
|
|
|
return nil
|
|
}
|