| // 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 successful Decrypt |
| Key []byte // only valid after a successful 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 |
| } |