chore: vendor

vendor/github.com/ProtonMail/go-crypto/openpgp/packet/private_key.go

@@ -0,0 +1,837 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"bytes"
+	"crypto"
+	"crypto/cipher"
+	"crypto/dsa"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha1"
+	"io"
+	"io/ioutil"
+	"math/big"
+	"strconv"
+	"time"
+
+	"github.com/ProtonMail/go-crypto/openpgp/ecdh"
+	"github.com/ProtonMail/go-crypto/openpgp/ecdsa"
+	"github.com/ProtonMail/go-crypto/openpgp/eddsa"
+	"github.com/ProtonMail/go-crypto/openpgp/elgamal"
+	"github.com/ProtonMail/go-crypto/openpgp/errors"
+	"github.com/ProtonMail/go-crypto/openpgp/internal/encoding"
+	"github.com/ProtonMail/go-crypto/openpgp/s2k"
+)
+
+// PrivateKey represents a possibly encrypted private key. See RFC 4880,
+// section 5.5.3.
+type PrivateKey struct {
+	PublicKey
+	Encrypted     bool // if true then the private key is unavailable until Decrypt has been called.
+	encryptedData []byte
+	cipher        CipherFunction
+	s2k           func(out, in []byte)
+	// An *{rsa|dsa|elgamal|ecdh|ecdsa|ed25519}.PrivateKey or
+	// crypto.Signer/crypto.Decrypter (Decryptor RSA only).
+	PrivateKey   interface{}
+	sha1Checksum bool
+	iv           []byte
+
+	// Type of encryption of the S2K packet
+	// Allowed values are 0 (Not encrypted), 254 (SHA1), or
+	// 255 (2-byte checksum)
+	s2kType S2KType
+	// Full parameters of the S2K packet
+	s2kParams *s2k.Params
+}
+
+// S2KType s2k packet type
+type S2KType uint8
+
+const (
+	// S2KNON unencrypt
+	S2KNON S2KType = 0
+	// S2KSHA1 sha1 sum check
+	S2KSHA1 S2KType = 254
+	// S2KCHECKSUM sum check
+	S2KCHECKSUM S2KType = 255
+)
+
+func NewRSAPrivateKey(creationTime time.Time, priv *rsa.PrivateKey) *PrivateKey {
+	pk := new(PrivateKey)
+	pk.PublicKey = *NewRSAPublicKey(creationTime, &priv.PublicKey)
+	pk.PrivateKey = priv
+	return pk
+}
+
+func NewDSAPrivateKey(creationTime time.Time, priv *dsa.PrivateKey) *PrivateKey {
+	pk := new(PrivateKey)
+	pk.PublicKey = *NewDSAPublicKey(creationTime, &priv.PublicKey)
+	pk.PrivateKey = priv
+	return pk
+}
+
+func NewElGamalPrivateKey(creationTime time.Time, priv *elgamal.PrivateKey) *PrivateKey {
+	pk := new(PrivateKey)
+	pk.PublicKey = *NewElGamalPublicKey(creationTime, &priv.PublicKey)
+	pk.PrivateKey = priv
+	return pk
+}
+
+func NewECDSAPrivateKey(creationTime time.Time, priv *ecdsa.PrivateKey) *PrivateKey {
+	pk := new(PrivateKey)
+	pk.PublicKey = *NewECDSAPublicKey(creationTime, &priv.PublicKey)
+	pk.PrivateKey = priv
+	return pk
+}
+
+func NewEdDSAPrivateKey(creationTime time.Time, priv *eddsa.PrivateKey) *PrivateKey {
+	pk := new(PrivateKey)
+	pk.PublicKey = *NewEdDSAPublicKey(creationTime, &priv.PublicKey)
+	pk.PrivateKey = priv
+	return pk
+}
+
+func NewECDHPrivateKey(creationTime time.Time, priv *ecdh.PrivateKey) *PrivateKey {
+	pk := new(PrivateKey)
+	pk.PublicKey = *NewECDHPublicKey(creationTime, &priv.PublicKey)
+	pk.PrivateKey = priv
+	return pk
+}
+
+// NewSignerPrivateKey creates a PrivateKey from a crypto.Signer that
+// implements RSA, ECDSA or EdDSA.
+func NewSignerPrivateKey(creationTime time.Time, signer interface{}) *PrivateKey {
+	pk := new(PrivateKey)
+	// In general, the public Keys should be used as pointers. We still
+	// type-switch on the values, for backwards-compatibility.
+	switch pubkey := signer.(type) {
+	case *rsa.PrivateKey:
+		pk.PublicKey = *NewRSAPublicKey(creationTime, &pubkey.PublicKey)
+	case rsa.PrivateKey:
+		pk.PublicKey = *NewRSAPublicKey(creationTime, &pubkey.PublicKey)
+	case *ecdsa.PrivateKey:
+		pk.PublicKey = *NewECDSAPublicKey(creationTime, &pubkey.PublicKey)
+	case ecdsa.PrivateKey:
+		pk.PublicKey = *NewECDSAPublicKey(creationTime, &pubkey.PublicKey)
+	case *eddsa.PrivateKey:
+		pk.PublicKey = *NewEdDSAPublicKey(creationTime, &pubkey.PublicKey)
+	case eddsa.PrivateKey:
+		pk.PublicKey = *NewEdDSAPublicKey(creationTime, &pubkey.PublicKey)
+	default:
+		panic("openpgp: unknown signer type in NewSignerPrivateKey")
+	}
+	pk.PrivateKey = signer
+	return pk
+}
+
+// NewDecrypterPrivateKey creates a PrivateKey from a *{rsa|elgamal|ecdh}.PrivateKey.
+func NewDecrypterPrivateKey(creationTime time.Time, decrypter interface{}) *PrivateKey {
+	pk := new(PrivateKey)
+	switch priv := decrypter.(type) {
+	case *rsa.PrivateKey:
+		pk.PublicKey = *NewRSAPublicKey(creationTime, &priv.PublicKey)
+	case *elgamal.PrivateKey:
+		pk.PublicKey = *NewElGamalPublicKey(creationTime, &priv.PublicKey)
+	case *ecdh.PrivateKey:
+		pk.PublicKey = *NewECDHPublicKey(creationTime, &priv.PublicKey)
+	default:
+		panic("openpgp: unknown decrypter type in NewDecrypterPrivateKey")
+	}
+	pk.PrivateKey = decrypter
+	return pk
+}
+
+func (pk *PrivateKey) parse(r io.Reader) (err error) {
+	err = (&pk.PublicKey).parse(r)
+	if err != nil {
+		return
+	}
+	v5 := pk.PublicKey.Version == 5
+
+	var buf [1]byte
+	_, err = readFull(r, buf[:])
+	if err != nil {
+		return
+	}
+	pk.s2kType = S2KType(buf[0])
+	var optCount [1]byte
+	if v5 {
+		if _, err = readFull(r, optCount[:]); err != nil {
+			return
+		}
+	}
+
+	switch pk.s2kType {
+	case S2KNON:
+		pk.s2k = nil
+		pk.Encrypted = false
+	case S2KSHA1, S2KCHECKSUM:
+		if v5 && pk.s2kType == S2KCHECKSUM {
+			return errors.StructuralError("wrong s2k identifier for version 5")
+		}
+		_, err = readFull(r, buf[:])
+		if err != nil {
+			return
+		}
+		pk.cipher = CipherFunction(buf[0])
+		if pk.cipher != 0 && !pk.cipher.IsSupported() {
+			return errors.UnsupportedError("unsupported cipher function in private key")
+		}
+		pk.s2kParams, err = s2k.ParseIntoParams(r)
+		if err != nil {
+			return
+		}
+		if pk.s2kParams.Dummy() {
+			return
+		}
+		pk.s2k, err = pk.s2kParams.Function()
+		if err != nil {
+			return
+		}
+		pk.Encrypted = true
+		if pk.s2kType == S2KSHA1 {
+			pk.sha1Checksum = true
+		}
+	default:
+		return errors.UnsupportedError("deprecated s2k function in private key")
+	}
+
+	if pk.Encrypted {
+		blockSize := pk.cipher.blockSize()
+		if blockSize == 0 {
+			return errors.UnsupportedError("unsupported cipher in private key: " + strconv.Itoa(int(pk.cipher)))
+		}
+		pk.iv = make([]byte, blockSize)
+		_, err = readFull(r, pk.iv)
+		if err != nil {
+			return
+		}
+	}
+
+	var privateKeyData []byte
+	if v5 {
+		var n [4]byte /* secret material four octet count */
+		_, err = readFull(r, n[:])
+		if err != nil {
+			return
+		}
+		count := uint32(uint32(n[0])<<24 | uint32(n[1])<<16 | uint32(n[2])<<8 | uint32(n[3]))
+		if !pk.Encrypted {
+			count = count + 2 /* two octet checksum */
+		}
+		privateKeyData = make([]byte, count)
+		_, err = readFull(r, privateKeyData)
+		if err != nil {
+			return
+		}
+	} else {
+		privateKeyData, err = ioutil.ReadAll(r)
+		if err != nil {
+			return
+		}
+	}
+	if !pk.Encrypted {
+		if len(privateKeyData) < 2 {
+			return errors.StructuralError("truncated private key data")
+		}
+		var sum uint16
+		for i := 0; i < len(privateKeyData)-2; i++ {
+			sum += uint16(privateKeyData[i])
+		}
+		if privateKeyData[len(privateKeyData)-2] != uint8(sum>>8) ||
+			privateKeyData[len(privateKeyData)-1] != uint8(sum) {
+			return errors.StructuralError("private key checksum failure")
+		}
+		privateKeyData = privateKeyData[:len(privateKeyData)-2]
+		return pk.parsePrivateKey(privateKeyData)
+	}
+
+	pk.encryptedData = privateKeyData
+	return
+}
+
+// Dummy returns true if the private key is a dummy key. This is a GNU extension.
+func (pk *PrivateKey) Dummy() bool {
+	return pk.s2kParams.Dummy()
+}
+
+func mod64kHash(d []byte) uint16 {
+	var h uint16
+	for _, b := range d {
+		h += uint16(b)
+	}
+	return h
+}
+
+func (pk *PrivateKey) Serialize(w io.Writer) (err error) {
+	contents := bytes.NewBuffer(nil)
+	err = pk.PublicKey.serializeWithoutHeaders(contents)
+	if err != nil {
+		return
+	}
+	if _, err = contents.Write([]byte{uint8(pk.s2kType)}); err != nil {
+		return
+	}
+
+	optional := bytes.NewBuffer(nil)
+	if pk.Encrypted || pk.Dummy() {
+		optional.Write([]byte{uint8(pk.cipher)})
+		if err := pk.s2kParams.Serialize(optional); err != nil {
+			return err
+		}
+		if pk.Encrypted {
+			optional.Write(pk.iv)
+		}
+	}
+	if pk.Version == 5 {
+		contents.Write([]byte{uint8(optional.Len())})
+	}
+	io.Copy(contents, optional)
+
+	if !pk.Dummy() {
+		l := 0
+		var priv []byte
+		if !pk.Encrypted {
+			buf := bytes.NewBuffer(nil)
+			err = pk.serializePrivateKey(buf)
+			if err != nil {
+				return err
+			}
+			l = buf.Len()
+			checksum := mod64kHash(buf.Bytes())
+			buf.Write([]byte{byte(checksum >> 8), byte(checksum)})
+			priv = buf.Bytes()
+		} else {
+			priv, l = pk.encryptedData, len(pk.encryptedData)
+		}
+
+		if pk.Version == 5 {
+			contents.Write([]byte{byte(l >> 24), byte(l >> 16), byte(l >> 8), byte(l)})
+		}
+		contents.Write(priv)
+	}
+
+	ptype := packetTypePrivateKey
+	if pk.IsSubkey {
+		ptype = packetTypePrivateSubkey
+	}
+	err = serializeHeader(w, ptype, contents.Len())
+	if err != nil {
+		return
+	}
+	_, err = io.Copy(w, contents)
+	if err != nil {
+		return
+	}
+	return
+}
+
+func serializeRSAPrivateKey(w io.Writer, priv *rsa.PrivateKey) error {
+	if _, err := w.Write(new(encoding.MPI).SetBig(priv.D).EncodedBytes()); err != nil {
+		return err
+	}
+	if _, err := w.Write(new(encoding.MPI).SetBig(priv.Primes[1]).EncodedBytes()); err != nil {
+		return err
+	}
+	if _, err := w.Write(new(encoding.MPI).SetBig(priv.Primes[0]).EncodedBytes()); err != nil {
+		return err
+	}
+	_, err := w.Write(new(encoding.MPI).SetBig(priv.Precomputed.Qinv).EncodedBytes())
+	return err
+}
+
+func serializeDSAPrivateKey(w io.Writer, priv *dsa.PrivateKey) error {
+	_, err := w.Write(new(encoding.MPI).SetBig(priv.X).EncodedBytes())
+	return err
+}
+
+func serializeElGamalPrivateKey(w io.Writer, priv *elgamal.PrivateKey) error {
+	_, err := w.Write(new(encoding.MPI).SetBig(priv.X).EncodedBytes())
+	return err
+}
+
+func serializeECDSAPrivateKey(w io.Writer, priv *ecdsa.PrivateKey) error {
+	_, err := w.Write(encoding.NewMPI(priv.MarshalIntegerSecret()).EncodedBytes())
+	return err
+}
+
+func serializeEdDSAPrivateKey(w io.Writer, priv *eddsa.PrivateKey) error {
+	_, err := w.Write(encoding.NewMPI(priv.MarshalByteSecret()).EncodedBytes())
+	return err
+}
+
+func serializeECDHPrivateKey(w io.Writer, priv *ecdh.PrivateKey) error {
+	_, err := w.Write(encoding.NewMPI(priv.MarshalByteSecret()).EncodedBytes())
+	return err
+}
+
+// decrypt decrypts an encrypted private key using a decryption key.
+func (pk *PrivateKey) decrypt(decryptionKey []byte) error {
+	if pk.Dummy() {
+		return errors.ErrDummyPrivateKey("dummy key found")
+	}
+	if !pk.Encrypted {
+		return nil
+	}
+
+	block := pk.cipher.new(decryptionKey)
+	cfb := cipher.NewCFBDecrypter(block, pk.iv)
+
+	data := make([]byte, len(pk.encryptedData))
+	cfb.XORKeyStream(data, pk.encryptedData)
+
+	if pk.sha1Checksum {
+		if len(data) < sha1.Size {
+			return errors.StructuralError("truncated private key data")
+		}
+		h := sha1.New()
+		h.Write(data[:len(data)-sha1.Size])
+		sum := h.Sum(nil)
+		if !bytes.Equal(sum, data[len(data)-sha1.Size:]) {
+			return errors.StructuralError("private key checksum failure")
+		}
+		data = data[:len(data)-sha1.Size]
+	} else {
+		if len(data) < 2 {
+			return errors.StructuralError("truncated private key data")
+		}
+		var sum uint16
+		for i := 0; i < len(data)-2; i++ {
+			sum += uint16(data[i])
+		}
+		if data[len(data)-2] != uint8(sum>>8) ||
+			data[len(data)-1] != uint8(sum) {
+			return errors.StructuralError("private key checksum failure")
+		}
+		data = data[:len(data)-2]
+	}
+
+	err := pk.parsePrivateKey(data)
+	if _, ok := err.(errors.KeyInvalidError); ok {
+		return errors.KeyInvalidError("invalid key parameters")
+	}
+	if err != nil {
+		return err
+	}
+
+	// Mark key as unencrypted
+	pk.s2kType = S2KNON
+	pk.s2k = nil
+	pk.Encrypted = false
+	pk.encryptedData = nil
+
+	return nil
+}
+
+func (pk *PrivateKey) decryptWithCache(passphrase []byte, keyCache *s2k.Cache) error {
+	if pk.Dummy() {
+		return errors.ErrDummyPrivateKey("dummy key found")
+	}
+	if !pk.Encrypted {
+		return nil
+	}
+
+	key, err := keyCache.GetOrComputeDerivedKey(passphrase, pk.s2kParams, pk.cipher.KeySize())
+	if err != nil {
+		return err
+	}
+	return pk.decrypt(key)
+}
+
+// Decrypt decrypts an encrypted private key using a passphrase.
+func (pk *PrivateKey) Decrypt(passphrase []byte) error {
+	if pk.Dummy() {
+		return errors.ErrDummyPrivateKey("dummy key found")
+	}
+	if !pk.Encrypted {
+		return nil
+	}
+
+	key := make([]byte, pk.cipher.KeySize())
+	pk.s2k(key, passphrase)
+	return pk.decrypt(key)
+}
+
+// DecryptPrivateKeys decrypts all encrypted keys with the given config and passphrase.
+// Avoids recomputation of similar s2k key derivations.
+func DecryptPrivateKeys(keys []*PrivateKey, passphrase []byte) error {
+	// Create a cache to avoid recomputation of key derviations for the same passphrase.
+	s2kCache := &s2k.Cache{}
+	for _, key := range keys {
+		if key != nil && !key.Dummy() && key.Encrypted {
+			err := key.decryptWithCache(passphrase, s2kCache)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// encrypt encrypts an unencrypted private key.
+func (pk *PrivateKey) encrypt(key []byte, params *s2k.Params, cipherFunction CipherFunction) error {
+	if pk.Dummy() {
+		return errors.ErrDummyPrivateKey("dummy key found")
+	}
+	if pk.Encrypted {
+		return nil
+	}
+	// check if encryptionKey has the correct size
+	if len(key) != cipherFunction.KeySize() {
+		return errors.InvalidArgumentError("supplied encryption key has the wrong size")
+	}
+
+	priv := bytes.NewBuffer(nil)
+	err := pk.serializePrivateKey(priv)
+	if err != nil {
+		return err
+	}
+
+	pk.cipher = cipherFunction
+	pk.s2kParams = params
+	pk.s2k, err = pk.s2kParams.Function()
+	if err != nil {
+		return err
+	}
+
+	privateKeyBytes := priv.Bytes()
+	pk.sha1Checksum = true
+	block := pk.cipher.new(key)
+	pk.iv = make([]byte, pk.cipher.blockSize())
+	_, err = rand.Read(pk.iv)
+	if err != nil {
+		return err
+	}
+	cfb := cipher.NewCFBEncrypter(block, pk.iv)
+
+	if pk.sha1Checksum {
+		pk.s2kType = S2KSHA1
+		h := sha1.New()
+		h.Write(privateKeyBytes)
+		sum := h.Sum(nil)
+		privateKeyBytes = append(privateKeyBytes, sum...)
+	} else {
+		pk.s2kType = S2KCHECKSUM
+		var sum uint16
+		for _, b := range privateKeyBytes {
+			sum += uint16(b)
+		}
+		priv.Write([]byte{uint8(sum >> 8), uint8(sum)})
+	}
+
+	pk.encryptedData = make([]byte, len(privateKeyBytes))
+	cfb.XORKeyStream(pk.encryptedData, privateKeyBytes)
+	pk.Encrypted = true
+	pk.PrivateKey = nil
+	return err
+}
+
+// EncryptWithConfig encrypts an unencrypted private key using the passphrase and the config.
+func (pk *PrivateKey) EncryptWithConfig(passphrase []byte, config *Config) error {
+	params, err := s2k.Generate(config.Random(), config.S2K())
+	if err != nil {
+		return err
+	}
+	// Derive an encryption key with the configured s2k function.
+	key := make([]byte, config.Cipher().KeySize())
+	s2k, err := params.Function()
+	if err != nil {
+		return err
+	}
+	s2k(key, passphrase)
+	// Encrypt the private key with the derived encryption key.
+	return pk.encrypt(key, params, config.Cipher())
+}
+
+// EncryptPrivateKeys encrypts all unencrypted keys with the given config and passphrase.
+// Only derives one key from the passphrase, which is then used to encrypt each key.
+func EncryptPrivateKeys(keys []*PrivateKey, passphrase []byte, config *Config) error {
+	params, err := s2k.Generate(config.Random(), config.S2K())
+	if err != nil {
+		return err
+	}
+	// Derive an encryption key with the configured s2k function.
+	encryptionKey := make([]byte, config.Cipher().KeySize())
+	s2k, err := params.Function()
+	if err != nil {
+		return err
+	}
+	s2k(encryptionKey, passphrase)
+	for _, key := range keys {
+		if key != nil && !key.Dummy() && !key.Encrypted {
+			err = key.encrypt(encryptionKey, params, config.Cipher())
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// Encrypt encrypts an unencrypted private key using a passphrase.
+func (pk *PrivateKey) Encrypt(passphrase []byte) error {
+	// Default config of private key encryption
+	config := &Config{
+		S2KConfig: &s2k.Config{
+			S2KMode:  s2k.IteratedSaltedS2K,
+			S2KCount: 65536,
+			Hash:     crypto.SHA256,
+		},
+		DefaultCipher: CipherAES256,
+	}
+	return pk.EncryptWithConfig(passphrase, config)
+}
+
+func (pk *PrivateKey) serializePrivateKey(w io.Writer) (err error) {
+	switch priv := pk.PrivateKey.(type) {
+	case *rsa.PrivateKey:
+		err = serializeRSAPrivateKey(w, priv)
+	case *dsa.PrivateKey:
+		err = serializeDSAPrivateKey(w, priv)
+	case *elgamal.PrivateKey:
+		err = serializeElGamalPrivateKey(w, priv)
+	case *ecdsa.PrivateKey:
+		err = serializeECDSAPrivateKey(w, priv)
+	case *eddsa.PrivateKey:
+		err = serializeEdDSAPrivateKey(w, priv)
+	case *ecdh.PrivateKey:
+		err = serializeECDHPrivateKey(w, priv)
+	default:
+		err = errors.InvalidArgumentError("unknown private key type")
+	}
+	return
+}
+
+func (pk *PrivateKey) parsePrivateKey(data []byte) (err error) {
+	switch pk.PublicKey.PubKeyAlgo {
+	case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly, PubKeyAlgoRSAEncryptOnly:
+		return pk.parseRSAPrivateKey(data)
+	case PubKeyAlgoDSA:
+		return pk.parseDSAPrivateKey(data)
+	case PubKeyAlgoElGamal:
+		return pk.parseElGamalPrivateKey(data)
+	case PubKeyAlgoECDSA:
+		return pk.parseECDSAPrivateKey(data)
+	case PubKeyAlgoECDH:
+		return pk.parseECDHPrivateKey(data)
+	case PubKeyAlgoEdDSA:
+		return pk.parseEdDSAPrivateKey(data)
+	}
+	panic("impossible")
+}
+
+func (pk *PrivateKey) parseRSAPrivateKey(data []byte) (err error) {
+	rsaPub := pk.PublicKey.PublicKey.(*rsa.PublicKey)
+	rsaPriv := new(rsa.PrivateKey)
+	rsaPriv.PublicKey = *rsaPub
+
+	buf := bytes.NewBuffer(data)
+	d := new(encoding.MPI)
+	if _, err := d.ReadFrom(buf); err != nil {
+		return err
+	}
+
+	p := new(encoding.MPI)
+	if _, err := p.ReadFrom(buf); err != nil {
+		return err
+	}
+
+	q := new(encoding.MPI)
+	if _, err := q.ReadFrom(buf); err != nil {
+		return err
+	}
+
+	rsaPriv.D = new(big.Int).SetBytes(d.Bytes())
+	rsaPriv.Primes = make([]*big.Int, 2)
+	rsaPriv.Primes[0] = new(big.Int).SetBytes(p.Bytes())
+	rsaPriv.Primes[1] = new(big.Int).SetBytes(q.Bytes())
+	if err := rsaPriv.Validate(); err != nil {
+		return errors.KeyInvalidError(err.Error())
+	}
+	rsaPriv.Precompute()
+	pk.PrivateKey = rsaPriv
+
+	return nil
+}
+
+func (pk *PrivateKey) parseDSAPrivateKey(data []byte) (err error) {
+	dsaPub := pk.PublicKey.PublicKey.(*dsa.PublicKey)
+	dsaPriv := new(dsa.PrivateKey)
+	dsaPriv.PublicKey = *dsaPub
+
+	buf := bytes.NewBuffer(data)
+	x := new(encoding.MPI)
+	if _, err := x.ReadFrom(buf); err != nil {
+		return err
+	}
+
+	dsaPriv.X = new(big.Int).SetBytes(x.Bytes())
+	if err := validateDSAParameters(dsaPriv); err != nil {
+		return err
+	}
+	pk.PrivateKey = dsaPriv
+
+	return nil
+}
+
+func (pk *PrivateKey) parseElGamalPrivateKey(data []byte) (err error) {
+	pub := pk.PublicKey.PublicKey.(*elgamal.PublicKey)
+	priv := new(elgamal.PrivateKey)
+	priv.PublicKey = *pub
+
+	buf := bytes.NewBuffer(data)
+	x := new(encoding.MPI)
+	if _, err := x.ReadFrom(buf); err != nil {
+		return err
+	}
+
+	priv.X = new(big.Int).SetBytes(x.Bytes())
+	if err := validateElGamalParameters(priv); err != nil {
+		return err
+	}
+	pk.PrivateKey = priv
+
+	return nil
+}
+
+func (pk *PrivateKey) parseECDSAPrivateKey(data []byte) (err error) {
+	ecdsaPub := pk.PublicKey.PublicKey.(*ecdsa.PublicKey)
+	ecdsaPriv := ecdsa.NewPrivateKey(*ecdsaPub)
+
+	buf := bytes.NewBuffer(data)
+	d := new(encoding.MPI)
+	if _, err := d.ReadFrom(buf); err != nil {
+		return err
+	}
+
+	if err := ecdsaPriv.UnmarshalIntegerSecret(d.Bytes()); err != nil {
+		return err
+	}
+	if err := ecdsa.Validate(ecdsaPriv); err != nil {
+		return err
+	}
+	pk.PrivateKey = ecdsaPriv
+
+	return nil
+}
+
+func (pk *PrivateKey) parseECDHPrivateKey(data []byte) (err error) {
+	ecdhPub := pk.PublicKey.PublicKey.(*ecdh.PublicKey)
+	ecdhPriv := ecdh.NewPrivateKey(*ecdhPub)
+
+	buf := bytes.NewBuffer(data)
+	d := new(encoding.MPI)
+	if _, err := d.ReadFrom(buf); err != nil {
+		return err
+	}
+
+	if err := ecdhPriv.UnmarshalByteSecret(d.Bytes()); err != nil {
+		return err
+	}
+
+	if err := ecdh.Validate(ecdhPriv); err != nil {
+		return err
+	}
+
+	pk.PrivateKey = ecdhPriv
+
+	return nil
+}
+
+func (pk *PrivateKey) parseEdDSAPrivateKey(data []byte) (err error) {
+	eddsaPub := pk.PublicKey.PublicKey.(*eddsa.PublicKey)
+	eddsaPriv := eddsa.NewPrivateKey(*eddsaPub)
+	eddsaPriv.PublicKey = *eddsaPub
+
+	buf := bytes.NewBuffer(data)
+	d := new(encoding.MPI)
+	if _, err := d.ReadFrom(buf); err != nil {
+		return err
+	}
+
+	if err = eddsaPriv.UnmarshalByteSecret(d.Bytes()); err != nil {
+		return err
+	}
+
+	if err := eddsa.Validate(eddsaPriv); err != nil {
+		return err
+	}
+
+	pk.PrivateKey = eddsaPriv
+
+	return nil
+}
+
+func validateDSAParameters(priv *dsa.PrivateKey) error {
+	p := priv.P // group prime
+	q := priv.Q // subgroup order
+	g := priv.G // g has order q mod p
+	x := priv.X // secret
+	y := priv.Y // y == g**x mod p
+	one := big.NewInt(1)
+	// expect g, y >= 2 and g < p
+	if g.Cmp(one) <= 0 || y.Cmp(one) <= 0 || g.Cmp(p) > 0 {
+		return errors.KeyInvalidError("dsa: invalid group")
+	}
+	// expect p > q
+	if p.Cmp(q) <= 0 {
+		return errors.KeyInvalidError("dsa: invalid group prime")
+	}
+	// q should be large enough and divide p-1
+	pSub1 := new(big.Int).Sub(p, one)
+	if q.BitLen() < 150 || new(big.Int).Mod(pSub1, q).Cmp(big.NewInt(0)) != 0 {
+		return errors.KeyInvalidError("dsa: invalid order")
+	}
+	// confirm that g has order q mod p
+	if !q.ProbablyPrime(32) || new(big.Int).Exp(g, q, p).Cmp(one) != 0 {
+		return errors.KeyInvalidError("dsa: invalid order")
+	}
+	// check y
+	if new(big.Int).Exp(g, x, p).Cmp(y) != 0 {
+		return errors.KeyInvalidError("dsa: mismatching values")
+	}
+
+	return nil
+}
+
+func validateElGamalParameters(priv *elgamal.PrivateKey) error {
+	p := priv.P // group prime
+	g := priv.G // g has order p-1 mod p
+	x := priv.X // secret
+	y := priv.Y // y == g**x mod p
+	one := big.NewInt(1)
+	// Expect g, y >= 2 and g < p
+	if g.Cmp(one) <= 0 || y.Cmp(one) <= 0 || g.Cmp(p) > 0 {
+		return errors.KeyInvalidError("elgamal: invalid group")
+	}
+	if p.BitLen() < 1024 {
+		return errors.KeyInvalidError("elgamal: group order too small")
+	}
+	pSub1 := new(big.Int).Sub(p, one)
+	if new(big.Int).Exp(g, pSub1, p).Cmp(one) != 0 {
+		return errors.KeyInvalidError("elgamal: invalid group")
+	}
+	// Since p-1 is not prime, g might have a smaller order that divides p-1.
+	// We cannot confirm the exact order of g, but we make sure it is not too small.
+	gExpI := new(big.Int).Set(g)
+	i := 1
+	threshold := 2 << 17 // we want order > threshold
+	for i < threshold {
+		i++ // we check every order to make sure key validation is not easily bypassed by guessing y'
+		gExpI.Mod(new(big.Int).Mul(gExpI, g), p)
+		if gExpI.Cmp(one) == 0 {
+			return errors.KeyInvalidError("elgamal: order too small")
+		}
+	}
+	// Check y
+	if new(big.Int).Exp(g, x, p).Cmp(y) != 0 {
+		return errors.KeyInvalidError("elgamal: mismatching values")
+	}
+
+	return nil
+}