// 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/aes" "crypto/cipher" "crypto/des" "crypto/hmac" "crypto/rc4" "crypto/sha1" "crypto/x509" "hash" ) // a keyAgreement implements the client and server side of a TLS key agreement // protocol by generating and processing key exchange messages. type keyAgreement interface { // On the server side, the first two methods are called in order. // In the case that the key agreement protocol doesn't use a // ServerKeyExchange message, generateServerKeyExchange can return nil, // nil. generateServerKeyExchange(*Config, *Certificate, *clientHelloMsg, *serverHelloMsg) (*serverKeyExchangeMsg, error) processClientKeyExchange(*Config, *Certificate, *clientKeyExchangeMsg, uint16) ([]byte, error) // On the client side, the next two methods are called in order. // This method may not be called if the server doesn't send a // ServerKeyExchange message. processServerKeyExchange(*Config, *clientHelloMsg, *serverHelloMsg, *x509.Certificate, *serverKeyExchangeMsg) error generateClientKeyExchange(*Config, *clientHelloMsg, *x509.Certificate) ([]byte, *clientKeyExchangeMsg, error) } // A cipherSuite is a specific combination of key agreement, cipher and MAC // function. All cipher suites currently assume RSA key agreement. 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() keyAgreement // If elliptic is set, a server will only consider this ciphersuite if // the ClientHello indicated that the client supports an elliptic curve // and point format that we can handle. elliptic bool cipher func(key, iv []byte, isRead bool) interface{} mac func(version uint16, macKey []byte) macFunction } var cipherSuites = []*cipherSuite{ {TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, false, cipherRC4, macSHA1}, {TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, false, cipher3DES, macSHA1}, {TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, false, cipherAES, macSHA1}, {TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, false, cipherAES, macSHA1}, {TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, true, cipherRC4, macSHA1}, {TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, true, cipher3DES, macSHA1}, {TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, true, cipherAES, macSHA1}, {TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, true, cipherAES, macSHA1}, } func cipherRC4(key, iv []byte, isRead bool) interface{} { cipher, _ := rc4.NewCipher(key) return cipher } func cipher3DES(key, iv []byte, isRead bool) interface{} { block, _ := des.NewTripleDESCipher(key) if isRead { return cipher.NewCBCDecrypter(block, iv) } return cipher.NewCBCEncrypter(block, iv) } func cipherAES(key, iv []byte, isRead bool) interface{} { block, _ := aes.NewCipher(key) if isRead { return cipher.NewCBCDecrypter(block, iv) } return cipher.NewCBCEncrypter(block, iv) } // macSHA1 returns a macFunction for the given protocol version. func macSHA1(version uint16, key []byte) macFunction { if version == versionSSL30 { mac := ssl30MAC{ h: sha1.New(), key: make([]byte, len(key)), } copy(mac.key, key) return mac } return tls10MAC{hmac.New(sha1.New, key)} } type macFunction interface { Size() int MAC(digestBuf, seq, data []byte) []byte } // ssl30MAC implements the SSLv3 MAC function, as defined in // www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 5.2.3.1 type ssl30MAC struct { h hash.Hash key []byte } func (s ssl30MAC) Size() int { return s.h.Size() } 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} 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} func (s ssl30MAC) MAC(digestBuf, seq, record []byte) []byte { padLength := 48 if s.h.Size() == 20 { padLength = 40 } s.h.Reset() s.h.Write(s.key) s.h.Write(ssl30Pad1[:padLength]) s.h.Write(seq) s.h.Write(record[:1]) s.h.Write(record[3:5]) s.h.Write(record[recordHeaderLen:]) digestBuf = s.h.Sum(digestBuf[:0]) s.h.Reset() s.h.Write(s.key) s.h.Write(ssl30Pad2[:padLength]) s.h.Write(digestBuf) return s.h.Sum(digestBuf[:0]) } // tls10MAC implements the TLS 1.0 MAC function. RFC 2246, section 6.2.3. type tls10MAC struct { h hash.Hash } func (s tls10MAC) Size() int { return s.h.Size() } func (s tls10MAC) MAC(digestBuf, seq, record []byte) []byte { s.h.Reset() s.h.Write(seq) s.h.Write(record) return s.h.Sum(digestBuf[:0]) } func rsaKA() keyAgreement { return rsaKeyAgreement{} } func ecdheRSAKA() keyAgreement { return new(ecdheRSAKeyAgreement) } // 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 { for _, suite := range cipherSuites { if suite.id == want { return suite } } return nil } } return nil } // A list of the possible cipher suite ids. Taken from // http://www.iana.org/assignments/tls-parameters/tls-parameters.xml const ( 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_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 )