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author | Péter Szilágyi <peterke@gmail.com> | 2016-11-03 00:22:53 +0800 |
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committer | Péter Szilágyi <peterke@gmail.com> | 2016-11-03 16:32:57 +0800 |
commit | bad0de0dcbae82d96f68d1eec1701042d5dfa985 (patch) | |
tree | 7b6e585f47a0c4bb9f6e3a17d549ca1d0ddbd642 /vendor/golang.org/x/crypto/openpgp/packet/symmetric_key_encrypted.go | |
parent | 3b62c145f8d699767e13770d1bb21d07c2ba9b46 (diff) | |
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vendor: pull in azure sdk and openpgp signer
Diffstat (limited to 'vendor/golang.org/x/crypto/openpgp/packet/symmetric_key_encrypted.go')
-rw-r--r-- | vendor/golang.org/x/crypto/openpgp/packet/symmetric_key_encrypted.go | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/openpgp/packet/symmetric_key_encrypted.go b/vendor/golang.org/x/crypto/openpgp/packet/symmetric_key_encrypted.go new file mode 100644 index 000000000..4b1105b6f --- /dev/null +++ b/vendor/golang.org/x/crypto/openpgp/packet/symmetric_key_encrypted.go @@ -0,0 +1,155 @@ +// 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/cipher" + "io" + "strconv" + + "golang.org/x/crypto/openpgp/errors" + "golang.org/x/crypto/openpgp/s2k" +) + +// This is the largest session key that we'll support. Since no 512-bit cipher +// has even been seriously used, this is comfortably large. +const maxSessionKeySizeInBytes = 64 + +// SymmetricKeyEncrypted represents a passphrase protected session key. See RFC +// 4880, section 5.3. +type SymmetricKeyEncrypted struct { + CipherFunc CipherFunction + s2k func(out, in []byte) + encryptedKey []byte +} + +const symmetricKeyEncryptedVersion = 4 + +func (ske *SymmetricKeyEncrypted) parse(r io.Reader) error { + // RFC 4880, section 5.3. + var buf [2]byte + if _, err := readFull(r, buf[:]); err != nil { + return err + } + if buf[0] != symmetricKeyEncryptedVersion { + return errors.UnsupportedError("SymmetricKeyEncrypted version") + } + ske.CipherFunc = CipherFunction(buf[1]) + + if ske.CipherFunc.KeySize() == 0 { + return errors.UnsupportedError("unknown cipher: " + strconv.Itoa(int(buf[1]))) + } + + var err error + ske.s2k, err = s2k.Parse(r) + if err != nil { + return err + } + + encryptedKey := make([]byte, maxSessionKeySizeInBytes) + // The session key may follow. We just have to try and read to find + // out. If it exists then we limit it to maxSessionKeySizeInBytes. + n, err := readFull(r, encryptedKey) + if err != nil && err != io.ErrUnexpectedEOF { + return err + } + + if n != 0 { + if n == maxSessionKeySizeInBytes { + return errors.UnsupportedError("oversized encrypted session key") + } + ske.encryptedKey = encryptedKey[:n] + } + + return nil +} + +// Decrypt attempts to decrypt an encrypted session key and returns the key and +// the cipher to use when decrypting a subsequent Symmetrically Encrypted Data +// packet. +func (ske *SymmetricKeyEncrypted) Decrypt(passphrase []byte) ([]byte, CipherFunction, error) { + key := make([]byte, ske.CipherFunc.KeySize()) + ske.s2k(key, passphrase) + + if len(ske.encryptedKey) == 0 { + return key, ske.CipherFunc, nil + } + + // the IV is all zeros + iv := make([]byte, ske.CipherFunc.blockSize()) + c := cipher.NewCFBDecrypter(ske.CipherFunc.new(key), iv) + plaintextKey := make([]byte, len(ske.encryptedKey)) + c.XORKeyStream(plaintextKey, ske.encryptedKey) + cipherFunc := CipherFunction(plaintextKey[0]) + if cipherFunc.blockSize() == 0 { + return nil, ske.CipherFunc, errors.UnsupportedError("unknown cipher: " + strconv.Itoa(int(cipherFunc))) + } + plaintextKey = plaintextKey[1:] + if l := len(plaintextKey); l == 0 || l%cipherFunc.blockSize() != 0 { + return nil, cipherFunc, errors.StructuralError("length of decrypted key not a multiple of block size") + } + + return plaintextKey, cipherFunc, nil +} + +// SerializeSymmetricKeyEncrypted serializes a symmetric key packet to w. The +// packet contains a random session key, encrypted by a key derived from the +// given passphrase. The session key is returned and must be passed to +// SerializeSymmetricallyEncrypted. +// If config is nil, sensible defaults will be used. +func SerializeSymmetricKeyEncrypted(w io.Writer, passphrase []byte, config *Config) (key []byte, err error) { + cipherFunc := config.Cipher() + keySize := cipherFunc.KeySize() + if keySize == 0 { + return nil, errors.UnsupportedError("unknown cipher: " + strconv.Itoa(int(cipherFunc))) + } + + s2kBuf := new(bytes.Buffer) + keyEncryptingKey := make([]byte, keySize) + // s2k.Serialize salts and stretches the passphrase, and writes the + // resulting key to keyEncryptingKey and the s2k descriptor to s2kBuf. + err = s2k.Serialize(s2kBuf, keyEncryptingKey, config.Random(), passphrase, &s2k.Config{Hash: config.Hash(), S2KCount: config.PasswordHashIterations()}) + if err != nil { + return + } + s2kBytes := s2kBuf.Bytes() + + packetLength := 2 /* header */ + len(s2kBytes) + 1 /* cipher type */ + keySize + err = serializeHeader(w, packetTypeSymmetricKeyEncrypted, packetLength) + if err != nil { + return + } + + var buf [2]byte + buf[0] = symmetricKeyEncryptedVersion + buf[1] = byte(cipherFunc) + _, err = w.Write(buf[:]) + if err != nil { + return + } + _, err = w.Write(s2kBytes) + if err != nil { + return + } + + sessionKey := make([]byte, keySize) + _, err = io.ReadFull(config.Random(), sessionKey) + if err != nil { + return + } + iv := make([]byte, cipherFunc.blockSize()) + c := cipher.NewCFBEncrypter(cipherFunc.new(keyEncryptingKey), iv) + encryptedCipherAndKey := make([]byte, keySize+1) + c.XORKeyStream(encryptedCipherAndKey, buf[1:]) + c.XORKeyStream(encryptedCipherAndKey[1:], sessionKey) + _, err = w.Write(encryptedCipherAndKey) + if err != nil { + return + } + + key = sessionKey + return +} |