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- // 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/hmac"
- "crypto/rc4"
- "crypto/x509"
- "hash"
- "os"
- )
-
- // 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, *clientHelloMsg, *serverHelloMsg) (*serverKeyExchangeMsg, os.Error)
- processClientKeyExchange(*Config, *clientKeyExchangeMsg) ([]byte, os.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) os.Error
- generateClientKeyExchange(*Config, *clientHelloMsg, *x509.Certificate) ([]byte, *clientKeyExchangeMsg, os.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 {
- // 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(macKey []byte) hash.Hash
- }
-
- var cipherSuites = map[uint16]*cipherSuite{
- TLS_RSA_WITH_RC4_128_SHA: &cipherSuite{16, 20, 0, rsaKA, false, cipherRC4, hmacSHA1},
- TLS_RSA_WITH_AES_128_CBC_SHA: &cipherSuite{16, 20, 16, rsaKA, false, cipherAES, hmacSHA1},
- TLS_ECDHE_RSA_WITH_RC4_128_SHA: &cipherSuite{16, 20, 0, ecdheRSAKA, true, cipherRC4, hmacSHA1},
- TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: &cipherSuite{16, 20, 16, ecdheRSAKA, true, cipherAES, hmacSHA1},
- }
-
- func cipherRC4(key, iv []byte, isRead bool) interface{} {
- cipher, _ := rc4.NewCipher(key)
- return cipher
- }
-
- func cipherAES(key, iv []byte, isRead bool) interface{} {
- block, _ := aes.NewCipher(key)
- if isRead {
- return cipher.NewCBCDecrypter(block, iv)
- }
- return cipher.NewCBCEncrypter(block, iv)
- }
-
- func hmacSHA1(key []byte) hash.Hash {
- return hmac.NewSHA1(key)
- }
-
- func rsaKA() keyAgreement {
- return rsaKeyAgreement{}
- }
-
- func ecdheRSAKA() keyAgreement {
- return new(ecdheRSAKeyAgreement)
- }
-
- // mutualCipherSuite returns a cipherSuite and its id given a list of supported
- // ciphersuites and the id requested by the peer.
- func mutualCipherSuite(have []uint16, want uint16) (suite *cipherSuite, id uint16) {
- for _, id := range have {
- if id == want {
- return cipherSuites[id], id
- }
- }
- return
- }
-
- // 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_AES_128_CBC_SHA uint16 = 0x002f
- TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011
- TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013
- )
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