libgo/go/crypto/tls/cipher_suites.go

   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.
   4
   5 package tls
   6
   7 import (
   8         "crypto/aes"
   9         "crypto/cipher"
  10         "crypto/des"
  11         "crypto/hmac"
  12         "crypto/rc4"
  13         "crypto/sha1"
  14         "crypto/sha256"
  15         "crypto/x509"
  16         "hash"
  17
  18         "golang_org/x/crypto/chacha20poly1305"
  19 )
  20
  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.
  25
  26         // In the case that the key agreement protocol doesn't use a
  27         // ServerKeyExchange message, generateServerKeyExchange can return nil,
  28         // nil.
  29         generateServerKeyExchange(*Config, *Certificate, *clientHelloMsg, *serverHelloMsg) (*serverKeyExchangeMsg, error)
  30         processClientKeyExchange(*Config, *Certificate, *clientKeyExchangeMsg, uint16) ([]byte, error)
  31
  32         // On the client side, the next two methods are called in order.
  33
  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)
  38 }
  39
  40 const (
  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
  49         // RSA based.
  50         suiteECDSA
  51         // suiteTLS12 indicates that the cipher suite should only be advertised
  52         // and accepted when using TLS 1.2.
  53         suiteTLS12
  54         // suiteSHA384 indicates that the cipher suite uses SHA384 as the
  55         // handshake hash.
  56         suiteSHA384
  57         // suiteDefaultOff indicates that this cipher suite is not included by
  58         // default.
  59         suiteDefaultOff
  60 )
  61
  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 {
  65         id uint16
  66         // the lengths, in bytes, of the key material needed for each component.
  67         keyLen int
  68         macLen int
  69         ivLen  int
  70         ka     func(version uint16) keyAgreement
  71         // flags is a bitmask of the suite* values, above.
  72         flags  int
  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
  76 }
  77
  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 | suiteDefaultOff, 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 | suiteDefaultOff, 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 | suiteDefaultOff, 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},
 100
 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},
 105 }
 106
 107 func cipherRC4(key, iv []byte, isRead bool) interface{} {
 108         cipher, _ := rc4.NewCipher(key)
 109         return cipher
 110 }
 111
 112 func cipher3DES(key, iv []byte, isRead bool) interface{} {
 113         block, _ := des.NewTripleDESCipher(key)
 114         if isRead {
 115                 return cipher.NewCBCDecrypter(block, iv)
 116         }
 117         return cipher.NewCBCEncrypter(block, iv)
 118 }
 119
 120 func cipherAES(key, iv []byte, isRead bool) interface{} {
 121         block, _ := aes.NewCipher(key)
 122         if isRead {
 123                 return cipher.NewCBCDecrypter(block, iv)
 124         }
 125         return cipher.NewCBCEncrypter(block, iv)
 126 }
 127
 128 // macSHA1 returns a macFunction for the given protocol version.
 129 func macSHA1(version uint16, key []byte) macFunction {
 130         if version == VersionSSL30 {
 131                 mac := ssl30MAC{
 132                         h:   sha1.New(),
 133                         key: make([]byte, len(key)),
 134                 }
 135                 copy(mac.key, key)
 136                 return mac
 137         }
 138         return tls10MAC{hmac.New(newConstantTimeHash(sha1.New), key)}
 139 }
 140
 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)}
 145 }
 146
 147 type macFunction interface {
 148         Size() int
 149         MAC(digestBuf, seq, header, data, extra []byte) []byte
 150 }
 151
 152 type aead interface {
 153         cipher.AEAD
 154
 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
 159 }
 160
 161 // fixedNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to
 162 // each call.
 163 type fixedNonceAEAD struct {
 164         // nonce contains the fixed part of the nonce in the first four bytes.
 165         nonce [12]byte
 166         aead  cipher.AEAD
 167 }
 168
 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 }
 172
 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)
 176 }
 177
 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)
 181 }
 182
 183 // xoredNonceAEAD wraps an AEAD by XORing in a fixed pattern to the nonce
 184 // before each call.
 185 type xorNonceAEAD struct {
 186         nonceMask [12]byte
 187         aead      cipher.AEAD
 188 }
 189
 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 }
 193
 194 func (f *xorNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
 195         for i, b := range nonce {
 196                 f.nonceMask[4+i] ^= b
 197         }
 198         result := f.aead.Seal(out, f.nonceMask[:], plaintext, additionalData)
 199         for i, b := range nonce {
 200                 f.nonceMask[4+i] ^= b
 201         }
 202
 203         return result
 204 }
 205
 206 func (f *xorNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) {
 207         for i, b := range nonce {
 208                 f.nonceMask[4+i] ^= b
 209         }
 210         result, err := f.aead.Open(out, f.nonceMask[:], plaintext, additionalData)
 211         for i, b := range nonce {
 212                 f.nonceMask[4+i] ^= b
 213         }
 214
 215         return result, err
 216 }
 217
 218 func aeadAESGCM(key, fixedNonce []byte) cipher.AEAD {
 219         aes, err := aes.NewCipher(key)
 220         if err != nil {
 221                 panic(err)
 222         }
 223         aead, err := cipher.NewGCM(aes)
 224         if err != nil {
 225                 panic(err)
 226         }
 227
 228         ret := &fixedNonceAEAD{aead: aead}
 229         copy(ret.nonce[:], fixedNonce)
 230         return ret
 231 }
 232
 233 func aeadChaCha20Poly1305(key, fixedNonce []byte) cipher.AEAD {
 234         aead, err := chacha20poly1305.New(key)
 235         if err != nil {
 236                 panic(err)
 237         }
 238
 239         ret := &xorNonceAEAD{aead: aead}
 240         copy(ret.nonceMask[:], fixedNonce)
 241         return ret
 242 }
 243
 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 {
 247         h   hash.Hash
 248         key []byte
 249 }
 250
 251 func (s ssl30MAC) Size() int {
 252         return s.h.Size()
 253 }
 254
 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}
 256
 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}
 258
 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 {
 262         padLength := 48
 263         if s.h.Size() == 20 {
 264                 padLength = 40
 265         }
 266
 267         s.h.Reset()
 268         s.h.Write(s.key)
 269         s.h.Write(ssl30Pad1[:padLength])
 270         s.h.Write(seq)
 271         s.h.Write(header[:1])
 272         s.h.Write(header[3:5])
 273         s.h.Write(data)
 274         digestBuf = s.h.Sum(digestBuf[:0])
 275
 276         s.h.Reset()
 277         s.h.Write(s.key)
 278         s.h.Write(ssl30Pad2[:padLength])
 279         s.h.Write(digestBuf)
 280         return s.h.Sum(digestBuf[:0])
 281 }
 282
 283 type constantTimeHash interface {
 284         hash.Hash
 285         ConstantTimeSum(b []byte) []byte
 286 }
 287
 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 {
 291         h constantTimeHash
 292 }
 293
 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) }
 299
 300 func newConstantTimeHash(h func() hash.Hash) func() hash.Hash {
 301         return func() hash.Hash {
 302                 return &cthWrapper{h().(constantTimeHash)}
 303         }
 304 }
 305
 306 // tls10MAC implements the TLS 1.0 MAC function. RFC 2246, section 6.2.3.
 307 type tls10MAC struct {
 308         h hash.Hash
 309 }
 310
 311 func (s tls10MAC) Size() int {
 312         return s.h.Size()
 313 }
 314
 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 {
 319         s.h.Reset()
 320         s.h.Write(seq)
 321         s.h.Write(header)
 322         s.h.Write(data)
 323         res := s.h.Sum(digestBuf[:0])
 324         if extra != nil {
 325                 s.h.Write(extra)
 326         }
 327         return res
 328 }
 329
 330 func rsaKA(version uint16) keyAgreement {
 331         return rsaKeyAgreement{}
 332 }
 333
 334 func ecdheECDSAKA(version uint16) keyAgreement {
 335         return &ecdheKeyAgreement{
 336                 isRSA:   false,
 337                 version: version,
 338         }
 339 }
 340
 341 func ecdheRSAKA(version uint16) keyAgreement {
 342         return &ecdheKeyAgreement{
 343                 isRSA:   true,
 344                 version: version,
 345         }
 346 }
 347
 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 {
 352                 if id == want {
 353                         for _, suite := range cipherSuites {
 354                                 if suite.id == want {
 355                                         return suite
 356                                 }
 357                         }
 358                         return nil
 359                 }
 360         }
 361         return nil
 362 }
 363
 364 // A list of cipher suite IDs that are, or have been, implemented by this
 365 // package.
 366 //
 367 // Taken from https://www.iana.org/assignments/tls-parameters/tls-parameters.xml
 368 const (
 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
 391
 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
 396 )