1 files changed, 66 insertions, 0 deletions
diff --git a/src/pkg/crypto/openpgp/packet/encrypted_key.go b/src/pkg/crypto/openpgp/packet/encrypted_key.go
new file mode 100644
index 000000000..4a926cdb1
--- /dev/null
+++ b/src/pkg/crypto/openpgp/packet/encrypted_key.go
@@ -0,0 +1,66 @@
+// 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 (
+	"crypto/openpgp/error"
+	"crypto/rand"
+	"crypto/rsa"
+	"encoding/binary"
+	"io"
+	"os"
+	"strconv"
+)
+
+// EncryptedKey represents a public-key encrypted session key. See RFC 4880,
+// section 5.1.
+type EncryptedKey struct {
+	KeyId      uint64
+	Algo       PublicKeyAlgorithm
+	Encrypted  []byte
+	CipherFunc CipherFunction // only valid after a sucessful Decrypt
+	Key        []byte         // only valid after a sucessful Decrypt
+}
+
+func (e *EncryptedKey) parse(r io.Reader) (err os.Error) {
+	var buf [10]byte
+	_, err = readFull(r, buf[:])
+	if err != nil {
+		return
+	}
+	if buf[0] != 3 {
+		return error.UnsupportedError("unknown EncryptedKey version " + strconv.Itoa(int(buf[0])))
+	}
+	e.KeyId = binary.BigEndian.Uint64(buf[1:9])
+	e.Algo = PublicKeyAlgorithm(buf[9])
+	if e.Algo == PubKeyAlgoRSA || e.Algo == PubKeyAlgoRSAEncryptOnly {
+		e.Encrypted, _, err = readMPI(r)
+	}
+	_, err = consumeAll(r)
+	return
+}
+
+// DecryptRSA decrypts an RSA encrypted session key with the given private key.
+func (e *EncryptedKey) DecryptRSA(priv *rsa.PrivateKey) (err os.Error) {
+	if e.Algo != PubKeyAlgoRSA && e.Algo != PubKeyAlgoRSAEncryptOnly {
+		return error.InvalidArgumentError("EncryptedKey not RSA encrypted")
+	}
+	b, err := rsa.DecryptPKCS1v15(rand.Reader, priv, e.Encrypted)
+	if err != nil {
+		return
+	}
+	e.CipherFunc = CipherFunction(b[0])
+	e.Key = b[1 : len(b)-2]
+	expectedChecksum := uint16(b[len(b)-2])<<8 | uint16(b[len(b)-1])
+	var checksum uint16
+	for _, v := range e.Key {
+		checksum += uint16(v)
+	}
+	if checksum != expectedChecksum {
+		return error.StructuralError("EncryptedKey checksum incorrect")
+	}
+
+	return
+}