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.
17 "golang.org/x/crypto/chacha20poly1305"
21 import "crypto/internal/boring"
23 // a keyAgreement implements the client and server side of a TLS key agreement
24 // protocol by generating and processing key exchange messages.
25 type keyAgreement interface {
26 // On the server side, the first two methods are called in order.
28 // In the case that the key agreement protocol doesn't use a
29 // ServerKeyExchange message, generateServerKeyExchange can return nil,
31 generateServerKeyExchange(*Config, *Certificate, *clientHelloMsg, *serverHelloMsg) (*serverKeyExchangeMsg, error)
32 processClientKeyExchange(*Config, *Certificate, *clientKeyExchangeMsg, uint16) ([]byte, error)
34 // On the client side, the next two methods are called in order.
36 // This method may not be called if the server doesn't send a
37 // ServerKeyExchange message.
38 processServerKeyExchange(*Config, *clientHelloMsg, *serverHelloMsg, *x509.Certificate, *serverKeyExchangeMsg) error
39 generateClientKeyExchange(*Config, *clientHelloMsg, *x509.Certificate) ([]byte, *clientKeyExchangeMsg, error)
43 // suiteECDHE indicates that the cipher suite involves elliptic curve
44 // Diffie-Hellman. This means that it should only be selected when the
45 // client indicates that it supports ECC with a curve and point format
46 // that we're happy with.
47 suiteECDHE = 1 << iota
48 // suiteECSign indicates that the cipher suite involves an ECDSA or
49 // EdDSA signature and therefore may only be selected when the server's
50 // certificate is ECDSA or EdDSA. If this is not set then the cipher suite
53 // suiteTLS12 indicates that the cipher suite should only be advertised
54 // and accepted when using TLS 1.2.
56 // suiteSHA384 indicates that the cipher suite uses SHA384 as the
59 // suiteDefaultOff indicates that this cipher suite is not included by
64 // A cipherSuite is a specific combination of key agreement, cipher and MAC function.
65 type cipherSuite struct {
67 // the lengths, in bytes, of the key material needed for each component.
71 ka func(version uint16) keyAgreement
72 // flags is a bitmask of the suite* values, above.
74 cipher func(key, iv []byte, isRead bool) interface{}
75 mac func(version uint16, macKey []byte) macFunction
76 aead func(key, fixedNonce []byte) aead
79 var cipherSuites = []*cipherSuite{
80 // Ciphersuite order is chosen so that ECDHE comes before plain RSA and
81 // AEADs are the top preference.
82 {TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadChaCha20Poly1305},
83 {TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteTLS12, nil, nil, aeadChaCha20Poly1305},
84 {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM},
85 {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteTLS12, nil, nil, aeadAESGCM},
86 {TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
87 {TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
88 {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteDefaultOff, cipherAES, macSHA256, nil},
89 {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil},
90 {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteTLS12 | suiteDefaultOff, cipherAES, macSHA256, nil},
91 {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECSign, cipherAES, macSHA1, nil},
92 {TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil},
93 {TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECSign, cipherAES, macSHA1, nil},
94 {TLS_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, rsaKA, suiteTLS12, nil, nil, aeadAESGCM},
95 {TLS_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, rsaKA, suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
96 {TLS_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, rsaKA, suiteTLS12 | suiteDefaultOff, cipherAES, macSHA256, nil},
97 {TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil},
98 {TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil},
99 {TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, suiteECDHE, cipher3DES, macSHA1, nil},
100 {TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, 0, cipher3DES, macSHA1, nil},
102 // RC4-based cipher suites are disabled by default.
103 {TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, suiteDefaultOff, cipherRC4, macSHA1, nil},
104 {TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, suiteECDHE | suiteDefaultOff, cipherRC4, macSHA1, nil},
105 {TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteDefaultOff, cipherRC4, macSHA1, nil},
108 // selectCipherSuite returns the first cipher suite from ids which is also in
109 // supportedIDs and passes the ok filter.
110 func selectCipherSuite(ids, supportedIDs []uint16, ok func(*cipherSuite) bool) *cipherSuite {
111 for _, id := range ids {
112 candidate := cipherSuiteByID(id)
113 if candidate == nil || !ok(candidate) {
117 for _, suppID := range supportedIDs {
126 // A cipherSuiteTLS13 defines only the pair of the AEAD algorithm and hash
127 // algorithm to be used with HKDF. See RFC 8446, Appendix B.4.
128 type cipherSuiteTLS13 struct {
131 aead func(key, fixedNonce []byte) aead
135 var cipherSuitesTLS13 = []*cipherSuiteTLS13{
136 {TLS_AES_128_GCM_SHA256, 16, aeadAESGCMTLS13, crypto.SHA256},
137 {TLS_CHACHA20_POLY1305_SHA256, 32, aeadChaCha20Poly1305, crypto.SHA256},
138 {TLS_AES_256_GCM_SHA384, 32, aeadAESGCMTLS13, crypto.SHA384},
141 func cipherRC4(key, iv []byte, isRead bool) interface{} {
142 cipher, _ := rc4.NewCipher(key)
146 func cipher3DES(key, iv []byte, isRead bool) interface{} {
147 block, _ := des.NewTripleDESCipher(key)
149 return cipher.NewCBCDecrypter(block, iv)
151 return cipher.NewCBCEncrypter(block, iv)
154 func cipherAES(key, iv []byte, isRead bool) interface{} {
155 block, _ := aes.NewCipher(key)
157 return cipher.NewCBCDecrypter(block, iv)
159 return cipher.NewCBCEncrypter(block, iv)
162 // macSHA1 returns a macFunction for the given protocol version.
163 func macSHA1(version uint16, key []byte) macFunction {
165 // The BoringCrypto SHA1 does not have a constant-time
166 // checksum function, so don't try to use it.
168 h = newConstantTimeHash(h)
170 return tls10MAC{h: hmac.New(h, key)}
173 // macSHA256 returns a SHA-256 based MAC. These are only supported in TLS 1.2
174 // so the given version is ignored.
175 func macSHA256(version uint16, key []byte) macFunction {
176 return tls10MAC{h: hmac.New(sha256.New, key)}
179 type macFunction interface {
180 // Size returns the length of the MAC.
182 // MAC appends the MAC of (seq, header, data) to out. The extra data is fed
183 // into the MAC after obtaining the result to normalize timing. The result
184 // is only valid until the next invocation of MAC as the buffer is reused.
185 MAC(seq, header, data, extra []byte) []byte
188 type aead interface {
191 // explicitNonceLen returns the number of bytes of explicit nonce
192 // included in each record. This is eight for older AEADs and
193 // zero for modern ones.
194 explicitNonceLen() int
199 noncePrefixLength = 4
202 // prefixNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to
204 type prefixNonceAEAD struct {
205 // nonce contains the fixed part of the nonce in the first four bytes.
206 nonce [aeadNonceLength]byte
210 func (f *prefixNonceAEAD) NonceSize() int { return aeadNonceLength - noncePrefixLength }
211 func (f *prefixNonceAEAD) Overhead() int { return f.aead.Overhead() }
212 func (f *prefixNonceAEAD) explicitNonceLen() int { return f.NonceSize() }
214 func (f *prefixNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
215 copy(f.nonce[4:], nonce)
216 return f.aead.Seal(out, f.nonce[:], plaintext, additionalData)
219 func (f *prefixNonceAEAD) Open(out, nonce, ciphertext, additionalData []byte) ([]byte, error) {
220 copy(f.nonce[4:], nonce)
221 return f.aead.Open(out, f.nonce[:], ciphertext, additionalData)
224 // xoredNonceAEAD wraps an AEAD by XORing in a fixed pattern to the nonce
226 type xorNonceAEAD struct {
227 nonceMask [aeadNonceLength]byte
231 func (f *xorNonceAEAD) NonceSize() int { return 8 } // 64-bit sequence number
232 func (f *xorNonceAEAD) Overhead() int { return f.aead.Overhead() }
233 func (f *xorNonceAEAD) explicitNonceLen() int { return 0 }
235 func (f *xorNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
236 for i, b := range nonce {
237 f.nonceMask[4+i] ^= b
239 result := f.aead.Seal(out, f.nonceMask[:], plaintext, additionalData)
240 for i, b := range nonce {
241 f.nonceMask[4+i] ^= b
247 func (f *xorNonceAEAD) Open(out, nonce, ciphertext, additionalData []byte) ([]byte, error) {
248 for i, b := range nonce {
249 f.nonceMask[4+i] ^= b
251 result, err := f.aead.Open(out, f.nonceMask[:], ciphertext, additionalData)
252 for i, b := range nonce {
253 f.nonceMask[4+i] ^= b
259 type gcmtls interface {
260 NewGCMTLS() (cipher.AEAD, error)
263 func aeadAESGCM(key, noncePrefix []byte) aead {
264 if len(noncePrefix) != noncePrefixLength {
265 panic("tls: internal error: wrong nonce length")
267 aes, err := aes.NewCipher(key)
272 if aesTLS, ok := aes.(gcmtls); ok {
273 aead, err = aesTLS.NewGCMTLS()
276 aead, err = cipher.NewGCM(aes)
282 ret := &prefixNonceAEAD{aead: aead}
283 copy(ret.nonce[:], noncePrefix)
287 func aeadAESGCMTLS13(key, nonceMask []byte) aead {
288 if len(nonceMask) != aeadNonceLength {
289 panic("tls: internal error: wrong nonce length")
291 aes, err := aes.NewCipher(key)
295 aead, err := cipher.NewGCM(aes)
300 ret := &xorNonceAEAD{aead: aead}
301 copy(ret.nonceMask[:], nonceMask)
305 func aeadChaCha20Poly1305(key, nonceMask []byte) aead {
306 if len(nonceMask) != aeadNonceLength {
307 panic("tls: internal error: wrong nonce length")
309 aead, err := chacha20poly1305.New(key)
314 ret := &xorNonceAEAD{aead: aead}
315 copy(ret.nonceMask[:], nonceMask)
319 type constantTimeHash interface {
321 ConstantTimeSum(b []byte) []byte
324 // cthWrapper wraps any hash.Hash that implements ConstantTimeSum, and replaces
325 // with that all calls to Sum. It's used to obtain a ConstantTimeSum-based HMAC.
326 type cthWrapper struct {
330 func (c *cthWrapper) Size() int { return c.h.Size() }
331 func (c *cthWrapper) BlockSize() int { return c.h.BlockSize() }
332 func (c *cthWrapper) Reset() { c.h.Reset() }
333 func (c *cthWrapper) Write(p []byte) (int, error) { return c.h.Write(p) }
334 func (c *cthWrapper) Sum(b []byte) []byte { return c.h.ConstantTimeSum(b) }
336 func newConstantTimeHash(h func() hash.Hash) func() hash.Hash {
338 return func() hash.Hash {
339 return &cthWrapper{h().(constantTimeHash)}
343 // tls10MAC implements the TLS 1.0 MAC function. RFC 2246, Section 6.2.3.
344 type tls10MAC struct {
349 func (s tls10MAC) Size() int {
353 // MAC is guaranteed to take constant time, as long as
354 // len(seq)+len(header)+len(data)+len(extra) is constant. extra is not fed into
355 // the MAC, but is only provided to make the timing profile constant.
356 func (s tls10MAC) MAC(seq, header, data, extra []byte) []byte {
361 res := s.h.Sum(s.buf[:0])
368 func rsaKA(version uint16) keyAgreement {
369 return rsaKeyAgreement{}
372 func ecdheECDSAKA(version uint16) keyAgreement {
373 return &ecdheKeyAgreement{
379 func ecdheRSAKA(version uint16) keyAgreement {
380 return &ecdheKeyAgreement{
386 // mutualCipherSuite returns a cipherSuite given a list of supported
387 // ciphersuites and the id requested by the peer.
388 func mutualCipherSuite(have []uint16, want uint16) *cipherSuite {
389 for _, id := range have {
391 return cipherSuiteByID(id)
397 func cipherSuiteByID(id uint16) *cipherSuite {
398 for _, cipherSuite := range cipherSuites {
399 if cipherSuite.id == id {
406 func mutualCipherSuiteTLS13(have []uint16, want uint16) *cipherSuiteTLS13 {
407 for _, id := range have {
409 return cipherSuiteTLS13ByID(id)
415 func cipherSuiteTLS13ByID(id uint16) *cipherSuiteTLS13 {
416 for _, cipherSuite := range cipherSuitesTLS13 {
417 if cipherSuite.id == id {
424 // A list of cipher suite IDs that are, or have been, implemented by this
427 // Taken from https://www.iana.org/assignments/tls-parameters/tls-parameters.xml
429 // TLS 1.0 - 1.2 cipher suites.
430 TLS_RSA_WITH_RC4_128_SHA uint16 = 0x0005
431 TLS_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0x000a
432 TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f
433 TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035
434 TLS_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0x003c
435 TLS_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0x009c
436 TLS_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0x009d
437 TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007
438 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009
439 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a
440 TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011
441 TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012
442 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013
443 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014
444 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc023
445 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc027
446 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02f
447 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b
448 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc030
449 TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc02c
450 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca8
451 TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca9
453 // TLS 1.3 cipher suites.
454 TLS_AES_128_GCM_SHA256 uint16 = 0x1301
455 TLS_AES_256_GCM_SHA384 uint16 = 0x1302
456 TLS_CHACHA20_POLY1305_SHA256 uint16 = 0x1303
458 // TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
459 // that the client is doing version fallback. See RFC 7507.
460 TLS_FALLBACK_SCSV uint16 = 0x5600