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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/go/crypto/tls/key_agreement.go | |
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Diffstat (limited to 'libgo/go/crypto/tls/key_agreement.go')
-rw-r--r-- | libgo/go/crypto/tls/key_agreement.go | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/libgo/go/crypto/tls/key_agreement.go b/libgo/go/crypto/tls/key_agreement.go new file mode 100644 index 000000000..861c64f04 --- /dev/null +++ b/libgo/go/crypto/tls/key_agreement.go @@ -0,0 +1,246 @@ +// 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 ( + "big" + "crypto/elliptic" + "crypto/md5" + "crypto/rsa" + "crypto/sha1" + "crypto/x509" + "io" + "os" +) + +// rsaKeyAgreement implements the standard TLS key agreement where the client +// encrypts the pre-master secret to the server's public key. +type rsaKeyAgreement struct{} + +func (ka rsaKeyAgreement) generateServerKeyExchange(config *Config, clientHello *clientHelloMsg, hello *serverHelloMsg) (*serverKeyExchangeMsg, os.Error) { + return nil, nil +} + +func (ka rsaKeyAgreement) processClientKeyExchange(config *Config, ckx *clientKeyExchangeMsg) ([]byte, os.Error) { + preMasterSecret := make([]byte, 48) + _, err := io.ReadFull(config.rand(), preMasterSecret[2:]) + if err != nil { + return nil, err + } + + if len(ckx.ciphertext) < 2 { + return nil, os.ErrorString("bad ClientKeyExchange") + } + ciphertextLen := int(ckx.ciphertext[0])<<8 | int(ckx.ciphertext[1]) + if ciphertextLen != len(ckx.ciphertext)-2 { + return nil, os.ErrorString("bad ClientKeyExchange") + } + ciphertext := ckx.ciphertext[2:] + + err = rsa.DecryptPKCS1v15SessionKey(config.rand(), config.Certificates[0].PrivateKey, ciphertext, preMasterSecret) + if err != nil { + return nil, err + } + // We don't check the version number in the premaster secret. For one, + // by checking it, we would leak information about the validity of the + // encrypted pre-master secret. Secondly, it provides only a small + // benefit against a downgrade attack and some implementations send the + // wrong version anyway. See the discussion at the end of section + // 7.4.7.1 of RFC 4346. + return preMasterSecret, nil +} + +func (ka rsaKeyAgreement) processServerKeyExchange(config *Config, clientHello *clientHelloMsg, serverHello *serverHelloMsg, cert *x509.Certificate, skx *serverKeyExchangeMsg) os.Error { + return os.ErrorString("unexpected ServerKeyExchange") +} + +func (ka rsaKeyAgreement) generateClientKeyExchange(config *Config, clientHello *clientHelloMsg, cert *x509.Certificate) ([]byte, *clientKeyExchangeMsg, os.Error) { + preMasterSecret := make([]byte, 48) + preMasterSecret[0] = byte(clientHello.vers >> 8) + preMasterSecret[1] = byte(clientHello.vers) + _, err := io.ReadFull(config.rand(), preMasterSecret[2:]) + if err != nil { + return nil, nil, err + } + + encrypted, err := rsa.EncryptPKCS1v15(config.rand(), cert.PublicKey.(*rsa.PublicKey), preMasterSecret) + if err != nil { + return nil, nil, err + } + ckx := new(clientKeyExchangeMsg) + ckx.ciphertext = make([]byte, len(encrypted)+2) + ckx.ciphertext[0] = byte(len(encrypted) >> 8) + ckx.ciphertext[1] = byte(len(encrypted)) + copy(ckx.ciphertext[2:], encrypted) + return preMasterSecret, ckx, nil +} + + +// md5SHA1Hash implements TLS 1.0's hybrid hash function which consists of the +// concatenation of an MD5 and SHA1 hash. +func md5SHA1Hash(slices ...[]byte) []byte { + md5sha1 := make([]byte, md5.Size+sha1.Size) + hmd5 := md5.New() + for _, slice := range slices { + hmd5.Write(slice) + } + copy(md5sha1, hmd5.Sum()) + + hsha1 := sha1.New() + for _, slice := range slices { + hsha1.Write(slice) + } + copy(md5sha1[md5.Size:], hsha1.Sum()) + return md5sha1 +} + +// ecdheRSAKeyAgreement implements a TLS key agreement where the server +// generates a ephemeral EC public/private key pair and signs it. The +// pre-master secret is then calculated using ECDH. +type ecdheRSAKeyAgreement struct { + privateKey []byte + curve *elliptic.Curve + x, y *big.Int +} + +func (ka *ecdheRSAKeyAgreement) generateServerKeyExchange(config *Config, clientHello *clientHelloMsg, hello *serverHelloMsg) (*serverKeyExchangeMsg, os.Error) { + var curveid uint16 + +Curve: + for _, c := range clientHello.supportedCurves { + switch c { + case curveP256: + ka.curve = elliptic.P256() + curveid = c + break Curve + case curveP384: + ka.curve = elliptic.P384() + curveid = c + break Curve + case curveP521: + ka.curve = elliptic.P521() + curveid = c + break Curve + } + } + + var x, y *big.Int + var err os.Error + ka.privateKey, x, y, err = ka.curve.GenerateKey(config.rand()) + if err != nil { + return nil, err + } + ecdhePublic := ka.curve.Marshal(x, y) + + // http://tools.ietf.org/html/rfc4492#section-5.4 + serverECDHParams := make([]byte, 1+2+1+len(ecdhePublic)) + serverECDHParams[0] = 3 // named curve + serverECDHParams[1] = byte(curveid >> 8) + serverECDHParams[2] = byte(curveid) + serverECDHParams[3] = byte(len(ecdhePublic)) + copy(serverECDHParams[4:], ecdhePublic) + + md5sha1 := md5SHA1Hash(clientHello.random, hello.random, serverECDHParams) + sig, err := rsa.SignPKCS1v15(config.rand(), config.Certificates[0].PrivateKey, rsa.HashMD5SHA1, md5sha1) + if err != nil { + return nil, os.ErrorString("failed to sign ECDHE parameters: " + err.String()) + } + + skx := new(serverKeyExchangeMsg) + skx.key = make([]byte, len(serverECDHParams)+2+len(sig)) + copy(skx.key, serverECDHParams) + k := skx.key[len(serverECDHParams):] + k[0] = byte(len(sig) >> 8) + k[1] = byte(len(sig)) + copy(k[2:], sig) + + return skx, nil +} + +func (ka *ecdheRSAKeyAgreement) processClientKeyExchange(config *Config, ckx *clientKeyExchangeMsg) ([]byte, os.Error) { + if len(ckx.ciphertext) == 0 || int(ckx.ciphertext[0]) != len(ckx.ciphertext)-1 { + return nil, os.ErrorString("bad ClientKeyExchange") + } + x, y := ka.curve.Unmarshal(ckx.ciphertext[1:]) + if x == nil { + return nil, os.ErrorString("bad ClientKeyExchange") + } + x, _ = ka.curve.ScalarMult(x, y, ka.privateKey) + preMasterSecret := make([]byte, (ka.curve.BitSize+7)>>3) + xBytes := x.Bytes() + copy(preMasterSecret[len(preMasterSecret)-len(xBytes):], xBytes) + + return preMasterSecret, nil +} + +func (ka *ecdheRSAKeyAgreement) processServerKeyExchange(config *Config, clientHello *clientHelloMsg, serverHello *serverHelloMsg, cert *x509.Certificate, skx *serverKeyExchangeMsg) os.Error { + if len(skx.key) < 4 { + goto Error + } + if skx.key[0] != 3 { // named curve + return os.ErrorString("server selected unsupported curve") + } + curveid := uint16(skx.key[1])<<8 | uint16(skx.key[2]) + + switch curveid { + case curveP256: + ka.curve = elliptic.P256() + case curveP384: + ka.curve = elliptic.P384() + case curveP521: + ka.curve = elliptic.P521() + default: + return os.ErrorString("server selected unsupported curve") + } + + publicLen := int(skx.key[3]) + if publicLen+4 > len(skx.key) { + goto Error + } + ka.x, ka.y = ka.curve.Unmarshal(skx.key[4 : 4+publicLen]) + if ka.x == nil { + goto Error + } + serverECDHParams := skx.key[:4+publicLen] + + sig := skx.key[4+publicLen:] + if len(sig) < 2 { + goto Error + } + sigLen := int(sig[0])<<8 | int(sig[1]) + if sigLen+2 != len(sig) { + goto Error + } + sig = sig[2:] + + md5sha1 := md5SHA1Hash(clientHello.random, serverHello.random, serverECDHParams) + return rsa.VerifyPKCS1v15(cert.PublicKey.(*rsa.PublicKey), rsa.HashMD5SHA1, md5sha1, sig) + +Error: + return os.ErrorString("invalid ServerKeyExchange") +} + +func (ka *ecdheRSAKeyAgreement) generateClientKeyExchange(config *Config, clientHello *clientHelloMsg, cert *x509.Certificate) ([]byte, *clientKeyExchangeMsg, os.Error) { + if ka.curve == nil { + return nil, nil, os.ErrorString("missing ServerKeyExchange message") + } + priv, mx, my, err := ka.curve.GenerateKey(config.rand()) + if err != nil { + return nil, nil, err + } + x, _ := ka.curve.ScalarMult(ka.x, ka.y, priv) + preMasterSecret := make([]byte, (ka.curve.BitSize+7)>>3) + xBytes := x.Bytes() + copy(preMasterSecret[len(preMasterSecret)-len(xBytes):], xBytes) + + serialised := ka.curve.Marshal(mx, my) + + ckx := new(clientKeyExchangeMsg) + ckx.ciphertext = make([]byte, 1+len(serialised)) + ckx.ciphertext[0] = byte(len(serialised)) + copy(ckx.ciphertext[1:], serialised) + + return preMasterSecret, ckx, nil +} |