| // Copyright 2010 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 tls |
| |
| import ( |
| "crypto/aes" |
| "crypto/cipher" |
| "crypto/des" |
| "crypto/hmac" |
| "crypto/rc4" |
| "crypto/sha1" |
| "crypto/sha256" |
| "crypto/x509" |
| "hash" |
| ) |
| |
| // a keyAgreement implements the client and server side of a TLS key agreement |
| // protocol by generating and processing key exchange messages. |
| type keyAgreement interface { |
| // On the server side, the first two methods are called in order. |
| |
| // In the case that the key agreement protocol doesn't use a |
| // ServerKeyExchange message, generateServerKeyExchange can return nil, |
| // nil. |
| generateServerKeyExchange(*Config, *Certificate, *clientHelloMsg, *serverHelloMsg) (*serverKeyExchangeMsg, error) |
| processClientKeyExchange(*Config, *Certificate, *clientKeyExchangeMsg, uint16) ([]byte, error) |
| |
| // On the client side, the next two methods are called in order. |
| |
| // This method may not be called if the server doesn't send a |
| // ServerKeyExchange message. |
| processServerKeyExchange(*Config, *clientHelloMsg, *serverHelloMsg, *x509.Certificate, *serverKeyExchangeMsg) error |
| generateClientKeyExchange(*Config, *clientHelloMsg, *x509.Certificate) ([]byte, *clientKeyExchangeMsg, error) |
| } |
| |
| const ( |
| // suiteECDH indicates that the cipher suite involves elliptic curve |
| // Diffie-Hellman. This means that it should only be selected when the |
| // client indicates that it supports ECC with a curve and point format |
| // that we're happy with. |
| suiteECDHE = 1 << iota |
| // suiteECDSA indicates that the cipher suite involves an ECDSA |
| // signature and therefore may only be selected when the server's |
| // certificate is ECDSA. If this is not set then the cipher suite is |
| // RSA based. |
| suiteECDSA |
| // suiteTLS12 indicates that the cipher suite should only be advertised |
| // and accepted when using TLS 1.2. |
| suiteTLS12 |
| // suiteSHA384 indicates that the cipher suite uses SHA384 as the |
| // handshake hash. |
| suiteSHA384 |
| // suiteDefaultOff indicates that this cipher suite is not included by |
| // default. |
| suiteDefaultOff |
| ) |
| |
| // A cipherSuite is a specific combination of key agreement, cipher and MAC |
| // function. All cipher suites currently assume RSA key agreement. |
| type cipherSuite struct { |
| id uint16 |
| // the lengths, in bytes, of the key material needed for each component. |
| keyLen int |
| macLen int |
| ivLen int |
| ka func(version uint16) keyAgreement |
| // flags is a bitmask of the suite* values, above. |
| flags int |
| cipher func(key, iv []byte, isRead bool) interface{} |
| mac func(version uint16, macKey []byte) macFunction |
| aead func(key, fixedNonce []byte) cipher.AEAD |
| } |
| |
| var cipherSuites = []*cipherSuite{ |
| // Ciphersuite order is chosen so that ECDHE comes before plain RSA and |
| // GCM is top preference. |
| {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM}, |
| {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadAESGCM}, |
| {TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM}, |
| {TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM}, |
| {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheRSAKA, suiteECDHE | suiteTLS12, cipherAES, macSHA256, nil}, |
| {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil}, |
| {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, cipherAES, macSHA256, nil}, |
| {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil}, |
| {TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil}, |
| {TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil}, |
| {TLS_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, rsaKA, suiteTLS12, nil, nil, aeadAESGCM}, |
| {TLS_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, rsaKA, suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM}, |
| {TLS_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, rsaKA, suiteTLS12, cipherAES, macSHA256, nil}, |
| {TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil}, |
| {TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil}, |
| {TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, suiteECDHE, cipher3DES, macSHA1, nil}, |
| {TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, 0, cipher3DES, macSHA1, nil}, |
| |
| // RC4-based cipher suites are disabled by default. |
| {TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, suiteDefaultOff, cipherRC4, macSHA1, nil}, |
| {TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, suiteECDHE | suiteDefaultOff, cipherRC4, macSHA1, nil}, |
| {TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteDefaultOff, cipherRC4, macSHA1, nil}, |
| } |
| |
| func cipherRC4(key, iv []byte, isRead bool) interface{} { |
| cipher, _ := rc4.NewCipher(key) |
| return cipher |
| } |
| |
| func cipher3DES(key, iv []byte, isRead bool) interface{} { |
| block, _ := des.NewTripleDESCipher(key) |
| if isRead { |
| return cipher.NewCBCDecrypter(block, iv) |
| } |
| return cipher.NewCBCEncrypter(block, iv) |
| } |
| |
| func cipherAES(key, iv []byte, isRead bool) interface{} { |
| block, _ := aes.NewCipher(key) |
| if isRead { |
| return cipher.NewCBCDecrypter(block, iv) |
| } |
| return cipher.NewCBCEncrypter(block, iv) |
| } |
| |
| // macSHA1 returns a macFunction for the given protocol version. |
| func macSHA1(version uint16, key []byte) macFunction { |
| if version == VersionSSL30 { |
| mac := ssl30MAC{ |
| h: sha1.New(), |
| key: make([]byte, len(key)), |
| } |
| copy(mac.key, key) |
| return mac |
| } |
| return tls10MAC{hmac.New(newConstantTimeHash(sha1.New), key)} |
| } |
| |
| // macSHA256 returns a SHA-256 based MAC. These are only supported in TLS 1.2 |
| // so the given version is ignored. |
| func macSHA256(version uint16, key []byte) macFunction { |
| return tls10MAC{hmac.New(sha256.New, key)} |
| } |
| |
| type macFunction interface { |
| Size() int |
| MAC(digestBuf, seq, header, data, extra []byte) []byte |
| } |
| |
| // fixedNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to |
| // each call. |
| type fixedNonceAEAD struct { |
| // sealNonce and openNonce are buffers where the larger nonce will be |
| // constructed. Since a seal and open operation may be running |
| // concurrently, there is a separate buffer for each. |
| sealNonce, openNonce []byte |
| aead cipher.AEAD |
| } |
| |
| func (f *fixedNonceAEAD) NonceSize() int { return 8 } |
| func (f *fixedNonceAEAD) Overhead() int { return f.aead.Overhead() } |
| |
| func (f *fixedNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte { |
| copy(f.sealNonce[len(f.sealNonce)-8:], nonce) |
| return f.aead.Seal(out, f.sealNonce, plaintext, additionalData) |
| } |
| |
| func (f *fixedNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) { |
| copy(f.openNonce[len(f.openNonce)-8:], nonce) |
| return f.aead.Open(out, f.openNonce, plaintext, additionalData) |
| } |
| |
| func aeadAESGCM(key, fixedNonce []byte) cipher.AEAD { |
| aes, err := aes.NewCipher(key) |
| if err != nil { |
| panic(err) |
| } |
| aead, err := cipher.NewGCM(aes) |
| if err != nil { |
| panic(err) |
| } |
| |
| nonce1, nonce2 := make([]byte, 12), make([]byte, 12) |
| copy(nonce1, fixedNonce) |
| copy(nonce2, fixedNonce) |
| |
| return &fixedNonceAEAD{nonce1, nonce2, aead} |
| } |
| |
| // ssl30MAC implements the SSLv3 MAC function, as defined in |
| // www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 5.2.3.1 |
| type ssl30MAC struct { |
| h hash.Hash |
| key []byte |
| } |
| |
| func (s ssl30MAC) Size() int { |
| return s.h.Size() |
| } |
| |
| var ssl30Pad1 = [48]byte{0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36} |
| |
| var ssl30Pad2 = [48]byte{0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c} |
| |
| // MAC does not offer constant timing guarantees for SSL v3.0, since it's deemed |
| // useless considering the similar, protocol-level POODLE vulnerability. |
| func (s ssl30MAC) MAC(digestBuf, seq, header, data, extra []byte) []byte { |
| padLength := 48 |
| if s.h.Size() == 20 { |
| padLength = 40 |
| } |
| |
| s.h.Reset() |
| s.h.Write(s.key) |
| s.h.Write(ssl30Pad1[:padLength]) |
| s.h.Write(seq) |
| s.h.Write(header[:1]) |
| s.h.Write(header[3:5]) |
| s.h.Write(data) |
| digestBuf = s.h.Sum(digestBuf[:0]) |
| |
| s.h.Reset() |
| s.h.Write(s.key) |
| s.h.Write(ssl30Pad2[:padLength]) |
| s.h.Write(digestBuf) |
| return s.h.Sum(digestBuf[:0]) |
| } |
| |
| type constantTimeHash interface { |
| hash.Hash |
| ConstantTimeSum(b []byte) []byte |
| } |
| |
| // cthWrapper wraps any hash.Hash that implements ConstantTimeSum, and replaces |
| // with that all calls to Sum. It's used to obtain a ConstantTimeSum-based HMAC. |
| type cthWrapper struct { |
| h constantTimeHash |
| } |
| |
| func (c *cthWrapper) Size() int { return c.h.Size() } |
| func (c *cthWrapper) BlockSize() int { return c.h.BlockSize() } |
| func (c *cthWrapper) Reset() { c.h.Reset() } |
| func (c *cthWrapper) Write(p []byte) (int, error) { return c.h.Write(p) } |
| func (c *cthWrapper) Sum(b []byte) []byte { return c.h.ConstantTimeSum(b) } |
| |
| func newConstantTimeHash(h func() hash.Hash) func() hash.Hash { |
| return func() hash.Hash { |
| return &cthWrapper{h().(constantTimeHash)} |
| } |
| } |
| |
| // tls10MAC implements the TLS 1.0 MAC function. RFC 2246, section 6.2.3. |
| type tls10MAC struct { |
| h hash.Hash |
| } |
| |
| func (s tls10MAC) Size() int { |
| return s.h.Size() |
| } |
| |
| // MAC is guaranteed to take constant time, as long as |
| // len(seq)+len(header)+len(data)+len(extra) is constant. extra is not fed into |
| // the MAC, but is only provided to make the timing profile constant. |
| func (s tls10MAC) MAC(digestBuf, seq, header, data, extra []byte) []byte { |
| s.h.Reset() |
| s.h.Write(seq) |
| s.h.Write(header) |
| s.h.Write(data) |
| res := s.h.Sum(digestBuf[:0]) |
| if extra != nil { |
| s.h.Write(extra) |
| } |
| return res |
| } |
| |
| func rsaKA(version uint16) keyAgreement { |
| return rsaKeyAgreement{} |
| } |
| |
| func ecdheECDSAKA(version uint16) keyAgreement { |
| return &ecdheKeyAgreement{ |
| sigType: signatureECDSA, |
| version: version, |
| } |
| } |
| |
| func ecdheRSAKA(version uint16) keyAgreement { |
| return &ecdheKeyAgreement{ |
| sigType: signatureRSA, |
| version: version, |
| } |
| } |
| |
| // mutualCipherSuite returns a cipherSuite given a list of supported |
| // ciphersuites and the id requested by the peer. |
| func mutualCipherSuite(have []uint16, want uint16) *cipherSuite { |
| for _, id := range have { |
| if id == want { |
| for _, suite := range cipherSuites { |
| if suite.id == want { |
| return suite |
| } |
| } |
| return nil |
| } |
| } |
| return nil |
| } |
| |
| // A list of cipher suite IDs that are, or have been, implemented by this |
| // package. |
| // |
| // Taken from http://www.iana.org/assignments/tls-parameters/tls-parameters.xml |
| const ( |
| TLS_RSA_WITH_RC4_128_SHA uint16 = 0x0005 |
| TLS_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0x000a |
| TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f |
| TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035 |
| TLS_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0x003c |
| TLS_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0x009c |
| TLS_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0x009d |
| TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007 |
| TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009 |
| TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a |
| TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011 |
| TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012 |
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013 |
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014 |
| TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc023 |
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc027 |
| TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02f |
| TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b |
| TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc030 |
| TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc02c |
| |
| // TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator |
| // that the client is doing version fallback. See |
| // https://tools.ietf.org/html/rfc7507. |
| TLS_FALLBACK_SCSV uint16 = 0x5600 |
| ) |
