1 // Copyright 2010 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
18 "golang_org/x/crypto/chacha20poly1305"
21 // a keyAgreement implements the client and server side of a TLS key agreement
22 // protocol by generating and processing key exchange messages.
23 type keyAgreement interface {
24 // On the server side, the first two methods are called in order.
26 // In the case that the key agreement protocol doesn't use a
27 // ServerKeyExchange message, generateServerKeyExchange can return nil,
29 generateServerKeyExchange(*Config, *Certificate, *clientHelloMsg, *serverHelloMsg) (*serverKeyExchangeMsg, error)
30 processClientKeyExchange(*Config, *Certificate, *clientKeyExchangeMsg, uint16) ([]byte, error)
32 // On the client side, the next two methods are called in order.
34 // This method may not be called if the server doesn't send a
35 // ServerKeyExchange message.
36 processServerKeyExchange(*Config, *clientHelloMsg, *serverHelloMsg, *x509.Certificate, *serverKeyExchangeMsg) error
37 generateClientKeyExchange(*Config, *clientHelloMsg, *x509.Certificate) ([]byte, *clientKeyExchangeMsg, error)
41 // suiteECDH indicates that the cipher suite involves elliptic curve
42 // Diffie-Hellman. This means that it should only be selected when the
43 // client indicates that it supports ECC with a curve and point format
44 // that we're happy with.
45 suiteECDHE = 1 << iota
46 // suiteECDSA indicates that the cipher suite involves an ECDSA
47 // signature and therefore may only be selected when the server's
48 // certificate is ECDSA. If this is not set then the cipher suite is
51 // suiteTLS12 indicates that the cipher suite should only be advertised
52 // and accepted when using TLS 1.2.
54 // suiteSHA384 indicates that the cipher suite uses SHA384 as the
57 // suiteDefaultOff indicates that this cipher suite is not included by
62 // A cipherSuite is a specific combination of key agreement, cipher and MAC
63 // function. All cipher suites currently assume RSA key agreement.
64 type cipherSuite struct {
66 // the lengths, in bytes, of the key material needed for each component.
70 ka func(version uint16) keyAgreement
71 // flags is a bitmask of the suite* values, above.
73 cipher func(key, iv []byte, isRead bool) interface{}
74 mac func(version uint16, macKey []byte) macFunction
75 aead func(key, fixedNonce []byte) cipher.AEAD
78 var cipherSuites = []*cipherSuite{
79 // Ciphersuite order is chosen so that ECDHE comes before plain RSA and
80 // AEADs are the top preference.
81 {TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadChaCha20Poly1305},
82 {TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadChaCha20Poly1305},
83 {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM},
84 {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadAESGCM},
85 {TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
86 {TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
87 {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheRSAKA, suiteECDHE | suiteTLS12, cipherAES, macSHA256, nil},
88 {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil},
89 {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, cipherAES, macSHA256, nil},
90 {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil},
91 {TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil},
92 {TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil},
93 {TLS_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, rsaKA, suiteTLS12, nil, nil, aeadAESGCM},
94 {TLS_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, rsaKA, suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
95 {TLS_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, rsaKA, suiteTLS12, cipherAES, macSHA256, nil},
96 {TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil},
97 {TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil},
98 {TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, suiteECDHE, cipher3DES, macSHA1, nil},
99 {TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, 0, cipher3DES, macSHA1, nil},
101 // RC4-based cipher suites are disabled by default.
102 {TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, suiteDefaultOff, cipherRC4, macSHA1, nil},
103 {TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, suiteECDHE | suiteDefaultOff, cipherRC4, macSHA1, nil},
104 {TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteDefaultOff, cipherRC4, macSHA1, nil},
107 func cipherRC4(key, iv []byte, isRead bool) interface{} {
108 cipher, _ := rc4.NewCipher(key)
112 func cipher3DES(key, iv []byte, isRead bool) interface{} {
113 block, _ := des.NewTripleDESCipher(key)
115 return cipher.NewCBCDecrypter(block, iv)
117 return cipher.NewCBCEncrypter(block, iv)
120 func cipherAES(key, iv []byte, isRead bool) interface{} {
121 block, _ := aes.NewCipher(key)
123 return cipher.NewCBCDecrypter(block, iv)
125 return cipher.NewCBCEncrypter(block, iv)
128 // macSHA1 returns a macFunction for the given protocol version.
129 func macSHA1(version uint16, key []byte) macFunction {
130 if version == VersionSSL30 {
133 key: make([]byte, len(key)),
138 return tls10MAC{hmac.New(newConstantTimeHash(sha1.New), key)}
141 // macSHA256 returns a SHA-256 based MAC. These are only supported in TLS 1.2
142 // so the given version is ignored.
143 func macSHA256(version uint16, key []byte) macFunction {
144 return tls10MAC{hmac.New(sha256.New, key)}
147 type macFunction interface {
149 MAC(digestBuf, seq, header, data, extra []byte) []byte
152 type aead interface {
155 // explicitIVLen returns the number of bytes used by the explicit nonce
156 // that is included in the record. This is eight for older AEADs and
157 // zero for modern ones.
158 explicitNonceLen() int
161 // fixedNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to
163 type fixedNonceAEAD struct {
164 // nonce contains the fixed part of the nonce in the first four bytes.
169 func (f *fixedNonceAEAD) NonceSize() int { return 8 }
170 func (f *fixedNonceAEAD) Overhead() int { return f.aead.Overhead() }
171 func (f *fixedNonceAEAD) explicitNonceLen() int { return 8 }
173 func (f *fixedNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
174 copy(f.nonce[4:], nonce)
175 return f.aead.Seal(out, f.nonce[:], plaintext, additionalData)
178 func (f *fixedNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) {
179 copy(f.nonce[4:], nonce)
180 return f.aead.Open(out, f.nonce[:], plaintext, additionalData)
183 // xoredNonceAEAD wraps an AEAD by XORing in a fixed pattern to the nonce
185 type xorNonceAEAD struct {
190 func (f *xorNonceAEAD) NonceSize() int { return 8 }
191 func (f *xorNonceAEAD) Overhead() int { return f.aead.Overhead() }
192 func (f *xorNonceAEAD) explicitNonceLen() int { return 0 }
194 func (f *xorNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
195 for i, b := range nonce {
196 f.nonceMask[4+i] ^= b
198 result := f.aead.Seal(out, f.nonceMask[:], plaintext, additionalData)
199 for i, b := range nonce {
200 f.nonceMask[4+i] ^= b
206 func (f *xorNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) {
207 for i, b := range nonce {
208 f.nonceMask[4+i] ^= b
210 result, err := f.aead.Open(out, f.nonceMask[:], plaintext, additionalData)
211 for i, b := range nonce {
212 f.nonceMask[4+i] ^= b
218 func aeadAESGCM(key, fixedNonce []byte) cipher.AEAD {
219 aes, err := aes.NewCipher(key)
223 aead, err := cipher.NewGCM(aes)
228 ret := &fixedNonceAEAD{aead: aead}
229 copy(ret.nonce[:], fixedNonce)
233 func aeadChaCha20Poly1305(key, fixedNonce []byte) cipher.AEAD {
234 aead, err := chacha20poly1305.New(key)
239 ret := &xorNonceAEAD{aead: aead}
240 copy(ret.nonceMask[:], fixedNonce)
244 // ssl30MAC implements the SSLv3 MAC function, as defined in
245 // www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 5.2.3.1
246 type ssl30MAC struct {
251 func (s ssl30MAC) Size() int {
255 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}
257 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}
259 // MAC does not offer constant timing guarantees for SSL v3.0, since it's deemed
260 // useless considering the similar, protocol-level POODLE vulnerability.
261 func (s ssl30MAC) MAC(digestBuf, seq, header, data, extra []byte) []byte {
263 if s.h.Size() == 20 {
269 s.h.Write(ssl30Pad1[:padLength])
271 s.h.Write(header[:1])
272 s.h.Write(header[3:5])
274 digestBuf = s.h.Sum(digestBuf[:0])
278 s.h.Write(ssl30Pad2[:padLength])
280 return s.h.Sum(digestBuf[:0])
283 type constantTimeHash interface {
285 ConstantTimeSum(b []byte) []byte
288 // cthWrapper wraps any hash.Hash that implements ConstantTimeSum, and replaces
289 // with that all calls to Sum. It's used to obtain a ConstantTimeSum-based HMAC.
290 type cthWrapper struct {
294 func (c *cthWrapper) Size() int { return c.h.Size() }
295 func (c *cthWrapper) BlockSize() int { return c.h.BlockSize() }
296 func (c *cthWrapper) Reset() { c.h.Reset() }
297 func (c *cthWrapper) Write(p []byte) (int, error) { return c.h.Write(p) }
298 func (c *cthWrapper) Sum(b []byte) []byte { return c.h.ConstantTimeSum(b) }
300 func newConstantTimeHash(h func() hash.Hash) func() hash.Hash {
301 return func() hash.Hash {
302 return &cthWrapper{h().(constantTimeHash)}
306 // tls10MAC implements the TLS 1.0 MAC function. RFC 2246, section 6.2.3.
307 type tls10MAC struct {
311 func (s tls10MAC) Size() int {
315 // MAC is guaranteed to take constant time, as long as
316 // len(seq)+len(header)+len(data)+len(extra) is constant. extra is not fed into
317 // the MAC, but is only provided to make the timing profile constant.
318 func (s tls10MAC) MAC(digestBuf, seq, header, data, extra []byte) []byte {
323 res := s.h.Sum(digestBuf[:0])
330 func rsaKA(version uint16) keyAgreement {
331 return rsaKeyAgreement{}
334 func ecdheECDSAKA(version uint16) keyAgreement {
335 return &ecdheKeyAgreement{
336 sigType: signatureECDSA,
341 func ecdheRSAKA(version uint16) keyAgreement {
342 return &ecdheKeyAgreement{
343 sigType: signatureRSA,
348 // mutualCipherSuite returns a cipherSuite given a list of supported
349 // ciphersuites and the id requested by the peer.
350 func mutualCipherSuite(have []uint16, want uint16) *cipherSuite {
351 for _, id := range have {
353 for _, suite := range cipherSuites {
354 if suite.id == want {
364 // A list of cipher suite IDs that are, or have been, implemented by this
367 // Taken from http://www.iana.org/assignments/tls-parameters/tls-parameters.xml
369 TLS_RSA_WITH_RC4_128_SHA uint16 = 0x0005
370 TLS_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0x000a
371 TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f
372 TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035
373 TLS_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0x003c
374 TLS_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0x009c
375 TLS_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0x009d
376 TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007
377 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009
378 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a
379 TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011
380 TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012
381 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013
382 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014
383 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc023
384 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc027
385 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02f
386 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b
387 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc030
388 TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc02c
389 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca8
390 TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca9
392 // TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
393 // that the client is doing version fallback. See
394 // https://tools.ietf.org/html/rfc7507.
395 TLS_FALLBACK_SCSV uint16 = 0x5600