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Diffstat (limited to 'src/crypto/tls/cipher_suites.go')
| -rw-r--r-- | src/crypto/tls/cipher_suites.go | 689 |
1 files changed, 689 insertions, 0 deletions
diff --git a/src/crypto/tls/cipher_suites.go b/src/crypto/tls/cipher_suites.go new file mode 100644 index 0000000..d164991 --- /dev/null +++ b/src/crypto/tls/cipher_suites.go @@ -0,0 +1,689 @@ +// Copyright 2010 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package tls + +import ( + "crypto" + "crypto/aes" + "crypto/cipher" + "crypto/des" + "crypto/hmac" + "crypto/rc4" + "crypto/sha1" + "crypto/sha256" + "fmt" + "hash" + "internal/cpu" + "runtime" + + "golang.org/x/crypto/chacha20poly1305" +) + +// CipherSuite is a TLS cipher suite. Note that most functions in this package +// accept and expose cipher suite IDs instead of this type. +type CipherSuite struct { + ID uint16 + Name string + + // Supported versions is the list of TLS protocol versions that can + // negotiate this cipher suite. + SupportedVersions []uint16 + + // Insecure is true if the cipher suite has known security issues + // due to its primitives, design, or implementation. + Insecure bool +} + +var ( + supportedUpToTLS12 = []uint16{VersionTLS10, VersionTLS11, VersionTLS12} + supportedOnlyTLS12 = []uint16{VersionTLS12} + supportedOnlyTLS13 = []uint16{VersionTLS13} +) + +// CipherSuites returns a list of cipher suites currently implemented by this +// package, excluding those with security issues, which are returned by +// InsecureCipherSuites. +// +// The list is sorted by ID. Note that the default cipher suites selected by +// this package might depend on logic that can't be captured by a static list, +// and might not match those returned by this function. +func CipherSuites() []*CipherSuite { + return []*CipherSuite{ + {TLS_RSA_WITH_AES_128_CBC_SHA, "TLS_RSA_WITH_AES_128_CBC_SHA", supportedUpToTLS12, false}, + {TLS_RSA_WITH_AES_256_CBC_SHA, "TLS_RSA_WITH_AES_256_CBC_SHA", supportedUpToTLS12, false}, + {TLS_RSA_WITH_AES_128_GCM_SHA256, "TLS_RSA_WITH_AES_128_GCM_SHA256", supportedOnlyTLS12, false}, + {TLS_RSA_WITH_AES_256_GCM_SHA384, "TLS_RSA_WITH_AES_256_GCM_SHA384", supportedOnlyTLS12, false}, + + {TLS_AES_128_GCM_SHA256, "TLS_AES_128_GCM_SHA256", supportedOnlyTLS13, false}, + {TLS_AES_256_GCM_SHA384, "TLS_AES_256_GCM_SHA384", supportedOnlyTLS13, false}, + {TLS_CHACHA20_POLY1305_SHA256, "TLS_CHACHA20_POLY1305_SHA256", supportedOnlyTLS13, false}, + + {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA", supportedUpToTLS12, false}, + {TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA", supportedUpToTLS12, false}, + {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA", supportedUpToTLS12, false}, + {TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA", supportedUpToTLS12, false}, + {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256", supportedOnlyTLS12, false}, + {TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384", supportedOnlyTLS12, false}, + {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256", supportedOnlyTLS12, false}, + {TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384", supportedOnlyTLS12, false}, + {TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256, "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256", supportedOnlyTLS12, false}, + {TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256, "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256", supportedOnlyTLS12, false}, + } +} + +// InsecureCipherSuites returns a list of cipher suites currently implemented by +// this package and which have security issues. +// +// Most applications should not use the cipher suites in this list, and should +// only use those returned by CipherSuites. +func InsecureCipherSuites() []*CipherSuite { + // This list includes RC4, CBC_SHA256, and 3DES cipher suites. See + // cipherSuitesPreferenceOrder for details. + return []*CipherSuite{ + {TLS_RSA_WITH_RC4_128_SHA, "TLS_RSA_WITH_RC4_128_SHA", supportedUpToTLS12, true}, + {TLS_RSA_WITH_3DES_EDE_CBC_SHA, "TLS_RSA_WITH_3DES_EDE_CBC_SHA", supportedUpToTLS12, true}, + {TLS_RSA_WITH_AES_128_CBC_SHA256, "TLS_RSA_WITH_AES_128_CBC_SHA256", supportedOnlyTLS12, true}, + {TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, "TLS_ECDHE_ECDSA_WITH_RC4_128_SHA", supportedUpToTLS12, true}, + {TLS_ECDHE_RSA_WITH_RC4_128_SHA, "TLS_ECDHE_RSA_WITH_RC4_128_SHA", supportedUpToTLS12, true}, + {TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA", supportedUpToTLS12, true}, + {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256", supportedOnlyTLS12, true}, + {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256", supportedOnlyTLS12, true}, + } +} + +// CipherSuiteName returns the standard name for the passed cipher suite ID +// (e.g. "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256"), or a fallback representation +// of the ID value if the cipher suite is not implemented by this package. +func CipherSuiteName(id uint16) string { + for _, c := range CipherSuites() { + if c.ID == id { + return c.Name + } + } + for _, c := range InsecureCipherSuites() { + if c.ID == id { + return c.Name + } + } + return fmt.Sprintf("0x%04X", id) +} + +const ( + // suiteECDHE indicates that the cipher suite involves elliptic curve + // Diffie-Hellman. This means that it should only be selected when the + // client indicates that it supports ECC with a curve and point format + // that we're happy with. + suiteECDHE = 1 << iota + // suiteECSign indicates that the cipher suite involves an ECDSA or + // EdDSA signature and therefore may only be selected when the server's + // certificate is ECDSA or EdDSA. If this is not set then the cipher suite + // is RSA based. + suiteECSign + // suiteTLS12 indicates that the cipher suite should only be advertised + // and accepted when using TLS 1.2. + suiteTLS12 + // suiteSHA384 indicates that the cipher suite uses SHA384 as the + // handshake hash. + suiteSHA384 +) + +// A cipherSuite is a TLS 1.0–1.2 cipher suite, and defines the key exchange +// mechanism, as well as the cipher+MAC pair or the AEAD. +type cipherSuite struct { + id uint16 + // the lengths, in bytes, of the key material needed for each component. + keyLen int + macLen int + ivLen int + ka func(version uint16) keyAgreement + // flags is a bitmask of the suite* values, above. + flags int + cipher func(key, iv []byte, isRead bool) any + mac func(key []byte) hash.Hash + aead func(key, fixedNonce []byte) aead +} + +var cipherSuites = []*cipherSuite{ // TODO: replace with a map, since the order doesn't matter. + {TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadChaCha20Poly1305}, + {TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteTLS12, nil, nil, aeadChaCha20Poly1305}, + {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM}, + {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteTLS12, nil, nil, aeadAESGCM}, + {TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM}, + {TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM}, + {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheRSAKA, suiteECDHE | suiteTLS12, cipherAES, macSHA256, nil}, + {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil}, + {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, ecdheECDSAKA, suiteECDHE | suiteECSign | suiteTLS12, cipherAES, macSHA256, nil}, + {TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECSign, cipherAES, macSHA1, nil}, + {TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil}, + {TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECSign, cipherAES, macSHA1, nil}, + {TLS_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, rsaKA, suiteTLS12, nil, nil, aeadAESGCM}, + {TLS_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, rsaKA, suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM}, + {TLS_RSA_WITH_AES_128_CBC_SHA256, 16, 32, 16, rsaKA, suiteTLS12, cipherAES, macSHA256, nil}, + {TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil}, + {TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil}, + {TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, suiteECDHE, cipher3DES, macSHA1, nil}, + {TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, 0, cipher3DES, macSHA1, nil}, + {TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, 0, cipherRC4, macSHA1, nil}, + {TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, suiteECDHE, cipherRC4, macSHA1, nil}, + {TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, suiteECDHE | suiteECSign, cipherRC4, macSHA1, nil}, +} + +// selectCipherSuite returns the first TLS 1.0–1.2 cipher suite from ids which +// is also in supportedIDs and passes the ok filter. +func selectCipherSuite(ids, supportedIDs []uint16, ok func(*cipherSuite) bool) *cipherSuite { + for _, id := range ids { + candidate := cipherSuiteByID(id) + if candidate == nil || !ok(candidate) { + continue + } + + for _, suppID := range supportedIDs { + if id == suppID { + return candidate + } + } + } + return nil +} + +// A cipherSuiteTLS13 defines only the pair of the AEAD algorithm and hash +// algorithm to be used with HKDF. See RFC 8446, Appendix B.4. +type cipherSuiteTLS13 struct { + id uint16 + keyLen int + aead func(key, fixedNonce []byte) aead + hash crypto.Hash +} + +var cipherSuitesTLS13 = []*cipherSuiteTLS13{ // TODO: replace with a map. + {TLS_AES_128_GCM_SHA256, 16, aeadAESGCMTLS13, crypto.SHA256}, + {TLS_CHACHA20_POLY1305_SHA256, 32, aeadChaCha20Poly1305, crypto.SHA256}, + {TLS_AES_256_GCM_SHA384, 32, aeadAESGCMTLS13, crypto.SHA384}, +} + +// cipherSuitesPreferenceOrder is the order in which we'll select (on the +// server) or advertise (on the client) TLS 1.0–1.2 cipher suites. +// +// Cipher suites are filtered but not reordered based on the application and +// peer's preferences, meaning we'll never select a suite lower in this list if +// any higher one is available. This makes it more defensible to keep weaker +// cipher suites enabled, especially on the server side where we get the last +// word, since there are no known downgrade attacks on cipher suites selection. +// +// The list is sorted by applying the following priority rules, stopping at the +// first (most important) applicable one: +// +// - Anything else comes before RC4 +// +// RC4 has practically exploitable biases. See https://www.rc4nomore.com. +// +// - Anything else comes before CBC_SHA256 +// +// SHA-256 variants of the CBC ciphersuites don't implement any Lucky13 +// countermeasures. See http://www.isg.rhul.ac.uk/tls/Lucky13.html and +// https://www.imperialviolet.org/2013/02/04/luckythirteen.html. +// +// - Anything else comes before 3DES +// +// 3DES has 64-bit blocks, which makes it fundamentally susceptible to +// birthday attacks. See https://sweet32.info. +// +// - ECDHE comes before anything else +// +// Once we got the broken stuff out of the way, the most important +// property a cipher suite can have is forward secrecy. We don't +// implement FFDHE, so that means ECDHE. +// +// - AEADs come before CBC ciphers +// +// Even with Lucky13 countermeasures, MAC-then-Encrypt CBC cipher suites +// are fundamentally fragile, and suffered from an endless sequence of +// padding oracle attacks. See https://eprint.iacr.org/2015/1129, +// https://www.imperialviolet.org/2014/12/08/poodleagain.html, and +// https://blog.cloudflare.com/yet-another-padding-oracle-in-openssl-cbc-ciphersuites/. +// +// - AES comes before ChaCha20 +// +// When AES hardware is available, AES-128-GCM and AES-256-GCM are faster +// than ChaCha20Poly1305. +// +// When AES hardware is not available, AES-128-GCM is one or more of: much +// slower, way more complex, and less safe (because not constant time) +// than ChaCha20Poly1305. +// +// We use this list if we think both peers have AES hardware, and +// cipherSuitesPreferenceOrderNoAES otherwise. +// +// - AES-128 comes before AES-256 +// +// The only potential advantages of AES-256 are better multi-target +// margins, and hypothetical post-quantum properties. Neither apply to +// TLS, and AES-256 is slower due to its four extra rounds (which don't +// contribute to the advantages above). +// +// - ECDSA comes before RSA +// +// The relative order of ECDSA and RSA cipher suites doesn't matter, +// as they depend on the certificate. Pick one to get a stable order. +// +var cipherSuitesPreferenceOrder = []uint16{ + // AEADs w/ ECDHE + TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, + TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, + TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, + + // CBC w/ ECDHE + TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, + TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, + + // AEADs w/o ECDHE + TLS_RSA_WITH_AES_128_GCM_SHA256, + TLS_RSA_WITH_AES_256_GCM_SHA384, + + // CBC w/o ECDHE + TLS_RSA_WITH_AES_128_CBC_SHA, + TLS_RSA_WITH_AES_256_CBC_SHA, + + // 3DES + TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, + TLS_RSA_WITH_3DES_EDE_CBC_SHA, + + // CBC_SHA256 + TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, + TLS_RSA_WITH_AES_128_CBC_SHA256, + + // RC4 + TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, TLS_ECDHE_RSA_WITH_RC4_128_SHA, + TLS_RSA_WITH_RC4_128_SHA, +} + +var cipherSuitesPreferenceOrderNoAES = []uint16{ + // ChaCha20Poly1305 + TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, + + // AES-GCM w/ ECDHE + TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, + TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, + + // The rest of cipherSuitesPreferenceOrder. + TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, + TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, + TLS_RSA_WITH_AES_128_GCM_SHA256, + TLS_RSA_WITH_AES_256_GCM_SHA384, + TLS_RSA_WITH_AES_128_CBC_SHA, + TLS_RSA_WITH_AES_256_CBC_SHA, + TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, + TLS_RSA_WITH_3DES_EDE_CBC_SHA, + TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, + TLS_RSA_WITH_AES_128_CBC_SHA256, + TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, TLS_ECDHE_RSA_WITH_RC4_128_SHA, + TLS_RSA_WITH_RC4_128_SHA, +} + +// disabledCipherSuites are not used unless explicitly listed in +// Config.CipherSuites. They MUST be at the end of cipherSuitesPreferenceOrder. +var disabledCipherSuites = []uint16{ + // CBC_SHA256 + TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, + TLS_RSA_WITH_AES_128_CBC_SHA256, + + // RC4 + TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, TLS_ECDHE_RSA_WITH_RC4_128_SHA, + TLS_RSA_WITH_RC4_128_SHA, +} + +var ( + defaultCipherSuitesLen = len(cipherSuitesPreferenceOrder) - len(disabledCipherSuites) + defaultCipherSuites = cipherSuitesPreferenceOrder[:defaultCipherSuitesLen] +) + +// defaultCipherSuitesTLS13 is also the preference order, since there are no +// disabled by default TLS 1.3 cipher suites. The same AES vs ChaCha20 logic as +// cipherSuitesPreferenceOrder applies. +var defaultCipherSuitesTLS13 = []uint16{ + TLS_AES_128_GCM_SHA256, + TLS_AES_256_GCM_SHA384, + TLS_CHACHA20_POLY1305_SHA256, +} + +var defaultCipherSuitesTLS13NoAES = []uint16{ + TLS_CHACHA20_POLY1305_SHA256, + TLS_AES_128_GCM_SHA256, + TLS_AES_256_GCM_SHA384, +} + +var ( + hasGCMAsmAMD64 = cpu.X86.HasAES && cpu.X86.HasPCLMULQDQ + hasGCMAsmARM64 = cpu.ARM64.HasAES && cpu.ARM64.HasPMULL + // Keep in sync with crypto/aes/cipher_s390x.go. + hasGCMAsmS390X = cpu.S390X.HasAES && cpu.S390X.HasAESCBC && cpu.S390X.HasAESCTR && + (cpu.S390X.HasGHASH || cpu.S390X.HasAESGCM) + + hasAESGCMHardwareSupport = runtime.GOARCH == "amd64" && hasGCMAsmAMD64 || + runtime.GOARCH == "arm64" && hasGCMAsmARM64 || + runtime.GOARCH == "s390x" && hasGCMAsmS390X +) + +var aesgcmCiphers = map[uint16]bool{ + // TLS 1.2 + TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256: true, + TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384: true, + TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: true, + TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: true, + // TLS 1.3 + TLS_AES_128_GCM_SHA256: true, + TLS_AES_256_GCM_SHA384: true, +} + +var nonAESGCMAEADCiphers = map[uint16]bool{ + // TLS 1.2 + TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305: true, + TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305: true, + // TLS 1.3 + TLS_CHACHA20_POLY1305_SHA256: true, +} + +// aesgcmPreferred returns whether the first known cipher in the preference list +// is an AES-GCM cipher, implying the peer has hardware support for it. +func aesgcmPreferred(ciphers []uint16) bool { + for _, cID := range ciphers { + if c := cipherSuiteByID(cID); c != nil { + return aesgcmCiphers[cID] + } + if c := cipherSuiteTLS13ByID(cID); c != nil { + return aesgcmCiphers[cID] + } + } + return false +} + +func cipherRC4(key, iv []byte, isRead bool) any { + cipher, _ := rc4.NewCipher(key) + return cipher +} + +func cipher3DES(key, iv []byte, isRead bool) any { + block, _ := des.NewTripleDESCipher(key) + if isRead { + return cipher.NewCBCDecrypter(block, iv) + } + return cipher.NewCBCEncrypter(block, iv) +} + +func cipherAES(key, iv []byte, isRead bool) any { + block, _ := aes.NewCipher(key) + if isRead { + return cipher.NewCBCDecrypter(block, iv) + } + return cipher.NewCBCEncrypter(block, iv) +} + +// macSHA1 returns a SHA-1 based constant time MAC. +func macSHA1(key []byte) hash.Hash { + return hmac.New(newConstantTimeHash(sha1.New), key) +} + +// macSHA256 returns a SHA-256 based MAC. This is only supported in TLS 1.2 and +// is currently only used in disabled-by-default cipher suites. +func macSHA256(key []byte) hash.Hash { + return hmac.New(sha256.New, key) +} + +type aead interface { + cipher.AEAD + + // explicitNonceLen returns the number of bytes of explicit nonce + // included in each record. This is eight for older AEADs and + // zero for modern ones. + explicitNonceLen() int +} + +const ( + aeadNonceLength = 12 + noncePrefixLength = 4 +) + +// prefixNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to +// each call. +type prefixNonceAEAD struct { + // nonce contains the fixed part of the nonce in the first four bytes. + nonce [aeadNonceLength]byte + aead cipher.AEAD +} + +func (f *prefixNonceAEAD) NonceSize() int { return aeadNonceLength - noncePrefixLength } +func (f *prefixNonceAEAD) Overhead() int { return f.aead.Overhead() } +func (f *prefixNonceAEAD) explicitNonceLen() int { return f.NonceSize() } + +func (f *prefixNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte { + copy(f.nonce[4:], nonce) + return f.aead.Seal(out, f.nonce[:], plaintext, additionalData) +} + +func (f *prefixNonceAEAD) Open(out, nonce, ciphertext, additionalData []byte) ([]byte, error) { + copy(f.nonce[4:], nonce) + return f.aead.Open(out, f.nonce[:], ciphertext, additionalData) +} + +// xoredNonceAEAD wraps an AEAD by XORing in a fixed pattern to the nonce +// before each call. +type xorNonceAEAD struct { + nonceMask [aeadNonceLength]byte + aead cipher.AEAD +} + +func (f *xorNonceAEAD) NonceSize() int { return 8 } // 64-bit sequence number +func (f *xorNonceAEAD) Overhead() int { return f.aead.Overhead() } +func (f *xorNonceAEAD) explicitNonceLen() int { return 0 } + +func (f *xorNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte { + for i, b := range nonce { + f.nonceMask[4+i] ^= b + } + result := f.aead.Seal(out, f.nonceMask[:], plaintext, additionalData) + for i, b := range nonce { + f.nonceMask[4+i] ^= b + } + + return result +} + +func (f *xorNonceAEAD) Open(out, nonce, ciphertext, additionalData []byte) ([]byte, error) { + for i, b := range nonce { + f.nonceMask[4+i] ^= b + } + result, err := f.aead.Open(out, f.nonceMask[:], ciphertext, additionalData) + for i, b := range nonce { + f.nonceMask[4+i] ^= b + } + + return result, err +} + +func aeadAESGCM(key, noncePrefix []byte) aead { + if len(noncePrefix) != noncePrefixLength { + panic("tls: internal error: wrong nonce length") + } + aes, err := aes.NewCipher(key) + if err != nil { + panic(err) + } + aead, err := cipher.NewGCM(aes) + if err != nil { + panic(err) + } + + ret := &prefixNonceAEAD{aead: aead} + copy(ret.nonce[:], noncePrefix) + return ret +} + +func aeadAESGCMTLS13(key, nonceMask []byte) aead { + if len(nonceMask) != aeadNonceLength { + panic("tls: internal error: wrong nonce length") + } + aes, err := aes.NewCipher(key) + if err != nil { + panic(err) + } + aead, err := cipher.NewGCM(aes) + if err != nil { + panic(err) + } + + ret := &xorNonceAEAD{aead: aead} + copy(ret.nonceMask[:], nonceMask) + return ret +} + +func aeadChaCha20Poly1305(key, nonceMask []byte) aead { + if len(nonceMask) != aeadNonceLength { + panic("tls: internal error: wrong nonce length") + } + aead, err := chacha20poly1305.New(key) + if err != nil { + panic(err) + } + + ret := &xorNonceAEAD{aead: aead} + copy(ret.nonceMask[:], nonceMask) + return ret +} + +type constantTimeHash interface { + hash.Hash + ConstantTimeSum(b []byte) []byte +} + +// cthWrapper wraps any hash.Hash that implements ConstantTimeSum, and replaces +// with that all calls to Sum. It's used to obtain a ConstantTimeSum-based HMAC. +type cthWrapper struct { + h constantTimeHash +} + +func (c *cthWrapper) Size() int { return c.h.Size() } +func (c *cthWrapper) BlockSize() int { return c.h.BlockSize() } +func (c *cthWrapper) Reset() { c.h.Reset() } +func (c *cthWrapper) Write(p []byte) (int, error) { return c.h.Write(p) } +func (c *cthWrapper) Sum(b []byte) []byte { return c.h.ConstantTimeSum(b) } + +func newConstantTimeHash(h func() hash.Hash) func() hash.Hash { + return func() hash.Hash { + return &cthWrapper{h().(constantTimeHash)} + } +} + +// tls10MAC implements the TLS 1.0 MAC function. RFC 2246, Section 6.2.3. +func tls10MAC(h hash.Hash, out, seq, header, data, extra []byte) []byte { + h.Reset() + h.Write(seq) + h.Write(header) + h.Write(data) + res := h.Sum(out) + if extra != nil { + h.Write(extra) + } + return res +} + +func rsaKA(version uint16) keyAgreement { + return rsaKeyAgreement{} +} + +func ecdheECDSAKA(version uint16) keyAgreement { + return &ecdheKeyAgreement{ + isRSA: false, + version: version, + } +} + +func ecdheRSAKA(version uint16) keyAgreement { + return &ecdheKeyAgreement{ + isRSA: true, + version: version, + } +} + +// mutualCipherSuite returns a cipherSuite given a list of supported +// ciphersuites and the id requested by the peer. +func mutualCipherSuite(have []uint16, want uint16) *cipherSuite { + for _, id := range have { + if id == want { + return cipherSuiteByID(id) + } + } + return nil +} + +func cipherSuiteByID(id uint16) *cipherSuite { + for _, cipherSuite := range cipherSuites { + if cipherSuite.id == id { + return cipherSuite + } + } + return nil +} + +func mutualCipherSuiteTLS13(have []uint16, want uint16) *cipherSuiteTLS13 { + for _, id := range have { + if id == want { + return cipherSuiteTLS13ByID(id) + } + } + return nil +} + +func cipherSuiteTLS13ByID(id uint16) *cipherSuiteTLS13 { + for _, cipherSuite := range cipherSuitesTLS13 { + if cipherSuite.id == id { + return cipherSuite + } + } + return nil +} + +// A list of cipher suite IDs that are, or have been, implemented by this +// package. +// +// See https://www.iana.org/assignments/tls-parameters/tls-parameters.xml +const ( + // TLS 1.0 - 1.2 cipher suites. + TLS_RSA_WITH_RC4_128_SHA uint16 = 0x0005 + TLS_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0x000a + TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f + TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035 + TLS_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0x003c + TLS_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0x009c + TLS_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0x009d + TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007 + TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009 + TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a + TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011 + TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012 + TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013 + TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014 + TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc023 + TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0xc027 + TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02f + TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b + TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc030 + TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc02c + TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 uint16 = 0xcca8 + TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 uint16 = 0xcca9 + + // TLS 1.3 cipher suites. + TLS_AES_128_GCM_SHA256 uint16 = 0x1301 + TLS_AES_256_GCM_SHA384 uint16 = 0x1302 + TLS_CHACHA20_POLY1305_SHA256 uint16 = 0x1303 + + // TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator + // that the client is doing version fallback. See RFC 7507. + TLS_FALLBACK_SCSV uint16 = 0x5600 + + // Legacy names for the corresponding cipher suites with the correct _SHA256 + // suffix, retained for backward compatibility. + TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305 = TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 + TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 = TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 +) |