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 // suiteECDH 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 // A cipherSuiteTLS13 defines only the pair of the AEAD algorithm and hash
109 // algorithm to be used with HKDF. See RFC 8446, Appendix B.4.
110 type cipherSuiteTLS13 struct {
113 aead func(key, fixedNonce []byte) aead
117 var cipherSuitesTLS13 = []*cipherSuiteTLS13{
118 {TLS_AES_128_GCM_SHA256, 16, aeadAESGCMTLS13, crypto.SHA256},
119 {TLS_CHACHA20_POLY1305_SHA256, 32, aeadChaCha20Poly1305, crypto.SHA256},
120 {TLS_AES_256_GCM_SHA384, 32, aeadAESGCMTLS13, crypto.SHA384},
123 func cipherRC4(key, iv []byte, isRead bool) interface{} {
124 cipher, _ := rc4.NewCipher(key)
128 func cipher3DES(key, iv []byte, isRead bool) interface{} {
129 block, _ := des.NewTripleDESCipher(key)
131 return cipher.NewCBCDecrypter(block, iv)
133 return cipher.NewCBCEncrypter(block, iv)
136 func cipherAES(key, iv []byte, isRead bool) interface{} {
137 block, _ := aes.NewCipher(key)
139 return cipher.NewCBCDecrypter(block, iv)
141 return cipher.NewCBCEncrypter(block, iv)
144 // macSHA1 returns a macFunction for the given protocol version.
145 func macSHA1(version uint16, key []byte) macFunction {
146 if version == VersionSSL30 {
149 key: make([]byte, len(key)),
155 // The BoringCrypto SHA1 does not have a constant-time
156 // checksum function, so don't try to use it.
158 h = newConstantTimeHash(h)
160 return tls10MAC{h: hmac.New(h, key)}
163 // macSHA256 returns a SHA-256 based MAC. These are only supported in TLS 1.2
164 // so the given version is ignored.
165 func macSHA256(version uint16, key []byte) macFunction {
166 return tls10MAC{h: hmac.New(sha256.New, key)}
169 type macFunction interface {
170 // Size returns the length of the MAC.
172 // MAC appends the MAC of (seq, header, data) to out. The extra data is fed
173 // into the MAC after obtaining the result to normalize timing. The result
174 // is only valid until the next invocation of MAC as the buffer is reused.
175 MAC(seq, header, data, extra []byte) []byte
178 type aead interface {
181 // explicitNonceLen returns the number of bytes of explicit nonce
182 // included in each record. This is eight for older AEADs and
183 // zero for modern ones.
184 explicitNonceLen() int
189 noncePrefixLength = 4
192 // prefixNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to
194 type prefixNonceAEAD struct {
195 // nonce contains the fixed part of the nonce in the first four bytes.
196 nonce [aeadNonceLength]byte
200 func (f *prefixNonceAEAD) NonceSize() int { return aeadNonceLength - noncePrefixLength }
201 func (f *prefixNonceAEAD) Overhead() int { return f.aead.Overhead() }
202 func (f *prefixNonceAEAD) explicitNonceLen() int { return f.NonceSize() }
204 func (f *prefixNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
205 copy(f.nonce[4:], nonce)
206 return f.aead.Seal(out, f.nonce[:], plaintext, additionalData)
209 func (f *prefixNonceAEAD) Open(out, nonce, ciphertext, additionalData []byte) ([]byte, error) {
210 copy(f.nonce[4:], nonce)
211 return f.aead.Open(out, f.nonce[:], ciphertext, additionalData)
214 // xoredNonceAEAD wraps an AEAD by XORing in a fixed pattern to the nonce
216 type xorNonceAEAD struct {
217 nonceMask [aeadNonceLength]byte
221 func (f *xorNonceAEAD) NonceSize() int { return 8 } // 64-bit sequence number
222 func (f *xorNonceAEAD) Overhead() int { return f.aead.Overhead() }
223 func (f *xorNonceAEAD) explicitNonceLen() int { return 0 }
225 func (f *xorNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
226 for i, b := range nonce {
227 f.nonceMask[4+i] ^= b
229 result := f.aead.Seal(out, f.nonceMask[:], plaintext, additionalData)
230 for i, b := range nonce {
231 f.nonceMask[4+i] ^= b
237 func (f *xorNonceAEAD) Open(out, nonce, ciphertext, additionalData []byte) ([]byte, error) {
238 for i, b := range nonce {
239 f.nonceMask[4+i] ^= b
241 result, err := f.aead.Open(out, f.nonceMask[:], ciphertext, additionalData)
242 for i, b := range nonce {
243 f.nonceMask[4+i] ^= b
249 type gcmtls interface {
250 NewGCMTLS() (cipher.AEAD, error)
253 func aeadAESGCM(key, noncePrefix []byte) aead {
254 if len(noncePrefix) != noncePrefixLength {
255 panic("tls: internal error: wrong nonce length")
257 aes, err := aes.NewCipher(key)
262 if aesTLS, ok := aes.(gcmtls); ok {
263 aead, err = aesTLS.NewGCMTLS()
266 aead, err = cipher.NewGCM(aes)
272 ret := &prefixNonceAEAD{aead: aead}
273 copy(ret.nonce[:], noncePrefix)
277 func aeadAESGCMTLS13(key, nonceMask []byte) aead {
278 if len(nonceMask) != aeadNonceLength {
279 panic("tls: internal error: wrong nonce length")
281 aes, err := aes.NewCipher(key)
285 aead, err := cipher.NewGCM(aes)
290 ret := &xorNonceAEAD{aead: aead}
291 copy(ret.nonceMask[:], nonceMask)
295 func aeadChaCha20Poly1305(key, nonceMask []byte) aead {
296 if len(nonceMask) != aeadNonceLength {
297 panic("tls: internal error: wrong nonce length")
299 aead, err := chacha20poly1305.New(key)
304 ret := &xorNonceAEAD{aead: aead}
305 copy(ret.nonceMask[:], nonceMask)
309 // ssl30MAC implements the SSLv3 MAC function, as defined in
310 // www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 5.2.3.1
311 type ssl30MAC struct {
317 func (s ssl30MAC) Size() int {
321 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}
323 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}
325 // MAC does not offer constant timing guarantees for SSL v3.0, since it's deemed
326 // useless considering the similar, protocol-level POODLE vulnerability.
327 func (s ssl30MAC) MAC(seq, header, data, extra []byte) []byte {
329 if s.h.Size() == 20 {
335 s.h.Write(ssl30Pad1[:padLength])
337 s.h.Write(header[:1])
338 s.h.Write(header[3:5])
340 s.buf = s.h.Sum(s.buf[:0])
344 s.h.Write(ssl30Pad2[:padLength])
346 return s.h.Sum(s.buf[:0])
349 type constantTimeHash interface {
351 ConstantTimeSum(b []byte) []byte
354 // cthWrapper wraps any hash.Hash that implements ConstantTimeSum, and replaces
355 // with that all calls to Sum. It's used to obtain a ConstantTimeSum-based HMAC.
356 type cthWrapper struct {
360 func (c *cthWrapper) Size() int { return c.h.Size() }
361 func (c *cthWrapper) BlockSize() int { return c.h.BlockSize() }
362 func (c *cthWrapper) Reset() { c.h.Reset() }
363 func (c *cthWrapper) Write(p []byte) (int, error) { return c.h.Write(p) }
364 func (c *cthWrapper) Sum(b []byte) []byte { return c.h.ConstantTimeSum(b) }
366 func newConstantTimeHash(h func() hash.Hash) func() hash.Hash {
368 return func() hash.Hash {
369 return &cthWrapper{h().(constantTimeHash)}
373 // tls10MAC implements the TLS 1.0 MAC function. RFC 2246, Section 6.2.3.
374 type tls10MAC struct {
379 func (s tls10MAC) Size() int {
383 // MAC is guaranteed to take constant time, as long as
384 // len(seq)+len(header)+len(data)+len(extra) is constant. extra is not fed into
385 // the MAC, but is only provided to make the timing profile constant.
386 func (s tls10MAC) MAC(seq, header, data, extra []byte) []byte {
391 res := s.h.Sum(s.buf[:0])
398 func rsaKA(version uint16) keyAgreement {
399 return rsaKeyAgreement{}
402 func ecdheECDSAKA(version uint16) keyAgreement {
403 return &ecdheKeyAgreement{
409 func ecdheRSAKA(version uint16) keyAgreement {
410 return &ecdheKeyAgreement{
416 // mutualCipherSuite returns a cipherSuite given a list of supported
417 // ciphersuites and the id requested by the peer.
418 func mutualCipherSuite(have []uint16, want uint16) *cipherSuite {
419 for _, id := range have {
421 return cipherSuiteByID(id)
427 func cipherSuiteByID(id uint16) *cipherSuite {
428 for _, cipherSuite := range cipherSuites {
429 if cipherSuite.id == id {
436 func mutualCipherSuiteTLS13(have []uint16, want uint16) *cipherSuiteTLS13 {
437 for _, id := range have {
439 return cipherSuiteTLS13ByID(id)
445 func cipherSuiteTLS13ByID(id uint16) *cipherSuiteTLS13 {
446 for _, cipherSuite := range cipherSuitesTLS13 {
447 if cipherSuite.id == id {
454 // A list of cipher suite IDs that are, or have been, implemented by this
457 // Taken from https://www.iana.org/assignments/tls-parameters/tls-parameters.xml
459 // TLS 1.0 - 1.2 cipher suites.
460 TLS_RSA_WITH_RC4_128_SHA uint16 = 0x0005
461 TLS_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0x000a
462 TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f
463 TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035
464 TLS_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0x003c
465 TLS_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0x009c
466 TLS_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0x009d
467 TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007
468 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009
469 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a
470 TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011
471 TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012
472 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013
473 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014
474 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc023
475 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc027
476 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02f
477 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b
478 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc030
479 TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc02c
480 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca8
481 TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca9
483 // TLS 1.3 cipher suites.
484 TLS_AES_128_GCM_SHA256 uint16 = 0x1301
485 TLS_AES_256_GCM_SHA384 uint16 = 0x1302
486 TLS_CHACHA20_POLY1305_SHA256 uint16 = 0x1303
488 // TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
489 // that the client is doing version fallback. See RFC 7507.
490 TLS_FALLBACK_SCSV uint16 = 0x5600