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.
16 "golang_org/x/crypto/chacha20poly1305"
20 // a keyAgreement implements the client and server side of a TLS key agreement
21 // protocol by generating and processing key exchange messages.
22 type keyAgreement interface {
23 // On the server side, the first two methods are called in order.
25 // In the case that the key agreement protocol doesn't use a
26 // ServerKeyExchange message, generateServerKeyExchange can return nil,
28 generateServerKeyExchange(*Config, *Certificate, *clientHelloMsg, *serverHelloMsg) (*serverKeyExchangeMsg, error)
29 processClientKeyExchange(*Config, *Certificate, *clientKeyExchangeMsg, uint16) ([]byte, error)
31 // On the client side, the next two methods are called in order.
33 // This method may not be called if the server doesn't send a
34 // ServerKeyExchange message.
35 processServerKeyExchange(*Config, *clientHelloMsg, *serverHelloMsg, *x509.Certificate, *serverKeyExchangeMsg) error
36 generateClientKeyExchange(*Config, *clientHelloMsg, *x509.Certificate) ([]byte, *clientKeyExchangeMsg, error)
40 // suiteECDH indicates that the cipher suite involves elliptic curve
41 // Diffie-Hellman. This means that it should only be selected when the
42 // client indicates that it supports ECC with a curve and point format
43 // that we're happy with.
44 suiteECDHE = 1 << iota
45 // suiteECDSA indicates that the cipher suite involves an ECDSA
46 // signature and therefore may only be selected when the server's
47 // certificate is ECDSA. If this is not set then the cipher suite is
50 // suiteTLS12 indicates that the cipher suite should only be advertised
51 // and accepted when using TLS 1.2.
53 // suiteSHA384 indicates that the cipher suite uses SHA384 as the
56 // suiteDefaultOff indicates that this cipher suite is not included by
61 // A cipherSuite is a specific combination of key agreement, cipher and MAC
62 // function. All cipher suites currently assume RSA key agreement.
63 type cipherSuite struct {
65 // the lengths, in bytes, of the key material needed for each component.
69 ka func(version uint16) keyAgreement
70 // flags is a bitmask of the suite* values, above.
72 cipher func(key, iv []byte, isRead bool) interface{}
73 mac func(version uint16, macKey []byte) macFunction
74 aead func(key, fixedNonce []byte) cipher.AEAD
77 var cipherSuites = []*cipherSuite{
78 // Ciphersuite order is chosen so that ECDHE comes before plain RSA and
79 // AEADs are the top preference.
80 {TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadChaCha20Poly1305},
81 {TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadChaCha20Poly1305},
82 {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM},
83 {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadAESGCM},
84 {TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
85 {TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
86 {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteDefaultOff, cipherAES, macSHA256, nil},
87 {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil},
88 {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12 | suiteDefaultOff, cipherAES, macSHA256, nil},
89 {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil},
90 {TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil},
91 {TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil},
92 {TLS_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, rsaKA, suiteTLS12, nil, nil, aeadAESGCM},
93 {TLS_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, rsaKA, suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
94 {TLS_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, rsaKA, suiteTLS12 | suiteDefaultOff, cipherAES, macSHA256, nil},
95 {TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil},
96 {TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil},
97 {TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, suiteECDHE, cipher3DES, macSHA1, nil},
98 {TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, 0, cipher3DES, macSHA1, nil},
100 // RC4-based cipher suites are disabled by default.
101 {TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, suiteDefaultOff, cipherRC4, macSHA1, nil},
102 {TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, suiteECDHE | suiteDefaultOff, cipherRC4, macSHA1, nil},
103 {TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteDefaultOff, cipherRC4, macSHA1, nil},
106 func cipherRC4(key, iv []byte, isRead bool) interface{} {
107 cipher, _ := rc4.NewCipher(key)
111 func cipher3DES(key, iv []byte, isRead bool) interface{} {
112 block, _ := des.NewTripleDESCipher(key)
114 return cipher.NewCBCDecrypter(block, iv)
116 return cipher.NewCBCEncrypter(block, iv)
119 func cipherAES(key, iv []byte, isRead bool) interface{} {
120 block, _ := aes.NewCipher(key)
122 return cipher.NewCBCDecrypter(block, iv)
124 return cipher.NewCBCEncrypter(block, iv)
127 // macSHA1 returns a macFunction for the given protocol version.
128 func macSHA1(version uint16, key []byte) macFunction {
129 if version == VersionSSL30 {
132 key: make([]byte, len(key)),
137 return tls10MAC{h: hmac.New(newConstantTimeHash(sha1.New), key)}
140 // macSHA256 returns a SHA-256 based MAC. These are only supported in TLS 1.2
141 // so the given version is ignored.
142 func macSHA256(version uint16, key []byte) macFunction {
143 return tls10MAC{h: hmac.New(sha256.New, key)}
146 type macFunction interface {
147 // Size returns the length of the MAC.
149 // MAC appends the MAC of (seq, header, data) to out. The extra data is fed
150 // into the MAC after obtaining the result to normalize timing. The result
151 // is only valid until the next invocation of MAC as the buffer is reused.
152 MAC(seq, header, data, extra []byte) []byte
155 type aead interface {
158 // explicitNonceLen returns the number of bytes of explicit nonce
159 // included in each record. This is eight for older AEADs and
160 // zero for modern ones.
161 explicitNonceLen() int
164 // fixedNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to
166 type fixedNonceAEAD struct {
167 // nonce contains the fixed part of the nonce in the first four bytes.
172 func (f *fixedNonceAEAD) NonceSize() int { return 8 }
173 func (f *fixedNonceAEAD) Overhead() int { return f.aead.Overhead() }
174 func (f *fixedNonceAEAD) explicitNonceLen() int { return 8 }
176 func (f *fixedNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
177 copy(f.nonce[4:], nonce)
178 return f.aead.Seal(out, f.nonce[:], plaintext, additionalData)
181 func (f *fixedNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) {
182 copy(f.nonce[4:], nonce)
183 return f.aead.Open(out, f.nonce[:], plaintext, additionalData)
186 // xoredNonceAEAD wraps an AEAD by XORing in a fixed pattern to the nonce
188 type xorNonceAEAD struct {
193 func (f *xorNonceAEAD) NonceSize() int { return 8 }
194 func (f *xorNonceAEAD) Overhead() int { return f.aead.Overhead() }
195 func (f *xorNonceAEAD) explicitNonceLen() int { return 0 }
197 func (f *xorNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
198 for i, b := range nonce {
199 f.nonceMask[4+i] ^= b
201 result := f.aead.Seal(out, f.nonceMask[:], plaintext, additionalData)
202 for i, b := range nonce {
203 f.nonceMask[4+i] ^= b
209 func (f *xorNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) {
210 for i, b := range nonce {
211 f.nonceMask[4+i] ^= b
213 result, err := f.aead.Open(out, f.nonceMask[:], plaintext, additionalData)
214 for i, b := range nonce {
215 f.nonceMask[4+i] ^= b
221 func aeadAESGCM(key, fixedNonce []byte) cipher.AEAD {
222 aes, err := aes.NewCipher(key)
226 aead, err := cipher.NewGCM(aes)
231 ret := &fixedNonceAEAD{aead: aead}
232 copy(ret.nonce[:], fixedNonce)
236 func aeadChaCha20Poly1305(key, fixedNonce []byte) cipher.AEAD {
237 aead, err := chacha20poly1305.New(key)
242 ret := &xorNonceAEAD{aead: aead}
243 copy(ret.nonceMask[:], fixedNonce)
247 // ssl30MAC implements the SSLv3 MAC function, as defined in
248 // www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 5.2.3.1
249 type ssl30MAC struct {
255 func (s ssl30MAC) Size() int {
259 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}
261 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}
263 // MAC does not offer constant timing guarantees for SSL v3.0, since it's deemed
264 // useless considering the similar, protocol-level POODLE vulnerability.
265 func (s ssl30MAC) MAC(seq, header, data, extra []byte) []byte {
267 if s.h.Size() == 20 {
273 s.h.Write(ssl30Pad1[:padLength])
275 s.h.Write(header[:1])
276 s.h.Write(header[3:5])
278 s.buf = s.h.Sum(s.buf[:0])
282 s.h.Write(ssl30Pad2[:padLength])
284 return s.h.Sum(s.buf[:0])
287 type constantTimeHash interface {
289 ConstantTimeSum(b []byte) []byte
292 // cthWrapper wraps any hash.Hash that implements ConstantTimeSum, and replaces
293 // with that all calls to Sum. It's used to obtain a ConstantTimeSum-based HMAC.
294 type cthWrapper struct {
298 func (c *cthWrapper) Size() int { return c.h.Size() }
299 func (c *cthWrapper) BlockSize() int { return c.h.BlockSize() }
300 func (c *cthWrapper) Reset() { c.h.Reset() }
301 func (c *cthWrapper) Write(p []byte) (int, error) { return c.h.Write(p) }
302 func (c *cthWrapper) Sum(b []byte) []byte { return c.h.ConstantTimeSum(b) }
304 func newConstantTimeHash(h func() hash.Hash) func() hash.Hash {
305 return func() hash.Hash {
306 return &cthWrapper{h().(constantTimeHash)}
310 // tls10MAC implements the TLS 1.0 MAC function. RFC 2246, Section 6.2.3.
311 type tls10MAC struct {
316 func (s tls10MAC) Size() int {
320 // MAC is guaranteed to take constant time, as long as
321 // len(seq)+len(header)+len(data)+len(extra) is constant. extra is not fed into
322 // the MAC, but is only provided to make the timing profile constant.
323 func (s tls10MAC) MAC(seq, header, data, extra []byte) []byte {
328 res := s.h.Sum(s.buf[:0])
335 func rsaKA(version uint16) keyAgreement {
336 return rsaKeyAgreement{}
339 func ecdheECDSAKA(version uint16) keyAgreement {
340 return &ecdheKeyAgreement{
346 func ecdheRSAKA(version uint16) keyAgreement {
347 return &ecdheKeyAgreement{
353 // mutualCipherSuite returns a cipherSuite given a list of supported
354 // ciphersuites and the id requested by the peer.
355 func mutualCipherSuite(have []uint16, want uint16) *cipherSuite {
356 for _, id := range have {
358 for _, suite := range cipherSuites {
359 if suite.id == want {
369 // A list of cipher suite IDs that are, or have been, implemented by this
372 // Taken from https://www.iana.org/assignments/tls-parameters/tls-parameters.xml
374 TLS_RSA_WITH_RC4_128_SHA uint16 = 0x0005
375 TLS_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0x000a
376 TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f
377 TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035
378 TLS_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0x003c
379 TLS_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0x009c
380 TLS_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0x009d
381 TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007
382 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009
383 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a
384 TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011
385 TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012
386 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013
387 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014
388 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc023
389 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc027
390 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02f
391 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b
392 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc030
393 TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc02c
394 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca8
395 TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca9
397 // TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
398 // that the client is doing version fallback. See RFC 7507.
399 TLS_FALLBACK_SCSV uint16 = 0x5600