mirror of
https://github.com/v2fly/v2ray-core.git
synced 2024-09-05 19:44:32 -04:00
403 lines
12 KiB
Go
403 lines
12 KiB
Go
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package qtls
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import (
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"crypto"
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"crypto/elliptic"
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"crypto/md5"
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"crypto/rsa"
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"crypto/sha1"
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"errors"
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"io"
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"math/big"
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"golang.org/x/crypto/curve25519"
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)
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var errClientKeyExchange = errors.New("tls: invalid ClientKeyExchange message")
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var errServerKeyExchange = errors.New("tls: invalid ServerKeyExchange message")
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// rsaKeyAgreement implements the standard TLS key agreement where the client
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// encrypts the pre-master secret to the server's public key.
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type rsaKeyAgreement struct{}
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func (ka rsaKeyAgreement) generateServerKeyExchange(config *Config, sk crypto.PrivateKey, clientHello *clientHelloMsg, hello *serverHelloMsg) (*serverKeyExchangeMsg, error) {
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return nil, nil
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}
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func (ka rsaKeyAgreement) processClientKeyExchange(config *Config, sk crypto.PrivateKey, ckx *clientKeyExchangeMsg, version uint16) ([]byte, error) {
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if len(ckx.ciphertext) < 2 {
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return nil, errClientKeyExchange
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}
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ciphertext := ckx.ciphertext
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if version != VersionSSL30 {
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ciphertextLen := int(ckx.ciphertext[0])<<8 | int(ckx.ciphertext[1])
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if ciphertextLen != len(ckx.ciphertext)-2 {
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return nil, errClientKeyExchange
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}
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ciphertext = ckx.ciphertext[2:]
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}
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priv, ok := sk.(crypto.Decrypter)
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if !ok {
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return nil, errors.New("tls: certificate private key does not implement crypto.Decrypter")
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}
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// Perform constant time RSA PKCS#1 v1.5 decryption
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preMasterSecret, err := priv.Decrypt(config.rand(), ciphertext, &rsa.PKCS1v15DecryptOptions{SessionKeyLen: 48})
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if err != nil {
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return nil, err
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}
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// We don't check the version number in the premaster secret. For one,
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// by checking it, we would leak information about the validity of the
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// encrypted pre-master secret. Secondly, it provides only a small
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// benefit against a downgrade attack and some implementations send the
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// wrong version anyway. See the discussion at the end of section
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// 7.4.7.1 of RFC 4346.
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return preMasterSecret, nil
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}
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func (ka rsaKeyAgreement) processServerKeyExchange(config *Config, clientHello *clientHelloMsg, serverHello *serverHelloMsg, pk crypto.PublicKey, skx *serverKeyExchangeMsg) error {
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return errors.New("tls: unexpected ServerKeyExchange")
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}
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func (ka rsaKeyAgreement) generateClientKeyExchange(config *Config, clientHello *clientHelloMsg, pk crypto.PublicKey) ([]byte, *clientKeyExchangeMsg, error) {
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preMasterSecret := make([]byte, 48)
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preMasterSecret[0] = byte(clientHello.vers >> 8)
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preMasterSecret[1] = byte(clientHello.vers)
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_, err := io.ReadFull(config.rand(), preMasterSecret[2:])
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if err != nil {
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return nil, nil, err
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}
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encrypted, err := rsa.EncryptPKCS1v15(config.rand(), pk.(*rsa.PublicKey), preMasterSecret)
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if err != nil {
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return nil, nil, err
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}
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ckx := new(clientKeyExchangeMsg)
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ckx.ciphertext = make([]byte, len(encrypted)+2)
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ckx.ciphertext[0] = byte(len(encrypted) >> 8)
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ckx.ciphertext[1] = byte(len(encrypted))
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copy(ckx.ciphertext[2:], encrypted)
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return preMasterSecret, ckx, nil
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}
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// sha1Hash calculates a SHA1 hash over the given byte slices.
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func sha1Hash(slices [][]byte) []byte {
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hsha1 := sha1.New()
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for _, slice := range slices {
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hsha1.Write(slice)
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}
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return hsha1.Sum(nil)
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}
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// md5SHA1Hash implements TLS 1.0's hybrid hash function which consists of the
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// concatenation of an MD5 and SHA1 hash.
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func md5SHA1Hash(slices [][]byte) []byte {
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md5sha1 := make([]byte, md5.Size+sha1.Size)
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hmd5 := md5.New()
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for _, slice := range slices {
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hmd5.Write(slice)
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}
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copy(md5sha1, hmd5.Sum(nil))
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copy(md5sha1[md5.Size:], sha1Hash(slices))
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return md5sha1
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}
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// hashForServerKeyExchange hashes the given slices and returns their digest
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// using the given hash function.
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func hashForServerKeyExchange(sigType uint8, hashFunc crypto.Hash, version uint16, slices ...[]byte) ([]byte, error) {
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if version >= VersionTLS12 {
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h := hashFunc.New()
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for _, slice := range slices {
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h.Write(slice)
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}
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digest := h.Sum(nil)
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return digest, nil
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}
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if sigType == signatureECDSA {
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return sha1Hash(slices), nil
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}
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return md5SHA1Hash(slices), nil
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}
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func curveForCurveID(id CurveID) (elliptic.Curve, bool) {
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switch id {
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case CurveP256:
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return elliptic.P256(), true
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case CurveP384:
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return elliptic.P384(), true
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case CurveP521:
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return elliptic.P521(), true
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default:
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return nil, false
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}
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}
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// ecdheKeyAgreement implements a TLS key agreement where the server
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// generates an ephemeral EC public/private key pair and signs it. The
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// pre-master secret is then calculated using ECDH. The signature may
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// either be ECDSA or RSA.
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type ecdheKeyAgreement struct {
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version uint16
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isRSA bool
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privateKey []byte
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curveid CurveID
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// publicKey is used to store the peer's public value when X25519 is
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// being used.
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publicKey []byte
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// x and y are used to store the peer's public value when one of the
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// NIST curves is being used.
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x, y *big.Int
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}
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func (ka *ecdheKeyAgreement) generateServerKeyExchange(config *Config, sk crypto.PrivateKey, clientHello *clientHelloMsg, hello *serverHelloMsg) (*serverKeyExchangeMsg, error) {
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preferredCurves := config.curvePreferences()
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NextCandidate:
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for _, candidate := range preferredCurves {
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for _, c := range clientHello.supportedCurves {
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if candidate == c {
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ka.curveid = c
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break NextCandidate
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}
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}
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}
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if ka.curveid == 0 {
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return nil, errors.New("tls: no supported elliptic curves offered")
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}
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var ecdhePublic []byte
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if ka.curveid == X25519 {
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var scalar, public [32]byte
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if _, err := io.ReadFull(config.rand(), scalar[:]); err != nil {
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return nil, err
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}
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curve25519.ScalarBaseMult(&public, &scalar)
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ka.privateKey = scalar[:]
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ecdhePublic = public[:]
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} else {
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curve, ok := curveForCurveID(ka.curveid)
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if !ok {
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return nil, errors.New("tls: preferredCurves includes unsupported curve")
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}
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var x, y *big.Int
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var err error
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ka.privateKey, x, y, err = elliptic.GenerateKey(curve, config.rand())
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if err != nil {
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return nil, err
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}
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ecdhePublic = elliptic.Marshal(curve, x, y)
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}
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// http://tools.ietf.org/html/rfc4492#section-5.4
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serverECDHParams := make([]byte, 1+2+1+len(ecdhePublic))
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serverECDHParams[0] = 3 // named curve
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serverECDHParams[1] = byte(ka.curveid >> 8)
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serverECDHParams[2] = byte(ka.curveid)
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serverECDHParams[3] = byte(len(ecdhePublic))
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copy(serverECDHParams[4:], ecdhePublic)
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priv, ok := sk.(crypto.Signer)
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if !ok {
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return nil, errors.New("tls: certificate private key does not implement crypto.Signer")
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}
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signatureAlgorithm, sigType, hashFunc, err := pickSignatureAlgorithm(priv.Public(), clientHello.supportedSignatureAlgorithms, supportedSignatureAlgorithms, ka.version)
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if err != nil {
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return nil, err
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}
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if (sigType == signaturePKCS1v15 || sigType == signatureRSAPSS) != ka.isRSA {
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return nil, errors.New("tls: certificate cannot be used with the selected cipher suite")
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}
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digest, err := hashForServerKeyExchange(sigType, hashFunc, ka.version, clientHello.random, hello.random, serverECDHParams)
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if err != nil {
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return nil, err
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}
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var sig []byte
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signOpts := crypto.SignerOpts(hashFunc)
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if sigType == signatureRSAPSS {
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signOpts = &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash, Hash: hashFunc}
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}
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sig, err = priv.Sign(config.rand(), digest, signOpts)
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if err != nil {
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return nil, errors.New("tls: failed to sign ECDHE parameters: " + err.Error())
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}
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skx := new(serverKeyExchangeMsg)
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sigAndHashLen := 0
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if ka.version >= VersionTLS12 {
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sigAndHashLen = 2
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}
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skx.key = make([]byte, len(serverECDHParams)+sigAndHashLen+2+len(sig))
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copy(skx.key, serverECDHParams)
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k := skx.key[len(serverECDHParams):]
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if ka.version >= VersionTLS12 {
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k[0] = byte(signatureAlgorithm >> 8)
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k[1] = byte(signatureAlgorithm)
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k = k[2:]
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}
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k[0] = byte(len(sig) >> 8)
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k[1] = byte(len(sig))
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copy(k[2:], sig)
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return skx, nil
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}
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func (ka *ecdheKeyAgreement) processClientKeyExchange(config *Config, sk crypto.PrivateKey, ckx *clientKeyExchangeMsg, version uint16) ([]byte, error) {
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if len(ckx.ciphertext) == 0 || int(ckx.ciphertext[0]) != len(ckx.ciphertext)-1 {
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return nil, errClientKeyExchange
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}
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if ka.curveid == X25519 {
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if len(ckx.ciphertext) != 1+32 {
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return nil, errClientKeyExchange
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}
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var theirPublic, sharedKey, scalar [32]byte
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copy(theirPublic[:], ckx.ciphertext[1:])
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copy(scalar[:], ka.privateKey)
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curve25519.ScalarMult(&sharedKey, &scalar, &theirPublic)
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return sharedKey[:], nil
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}
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curve, ok := curveForCurveID(ka.curveid)
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if !ok {
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panic("internal error")
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}
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x, y := elliptic.Unmarshal(curve, ckx.ciphertext[1:]) // Unmarshal also checks whether the given point is on the curve
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if x == nil {
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return nil, errClientKeyExchange
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}
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x, _ = curve.ScalarMult(x, y, ka.privateKey)
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curveSize := (curve.Params().BitSize + 7) >> 3
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xBytes := x.Bytes()
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if len(xBytes) == curveSize {
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return xBytes, nil
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}
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preMasterSecret := make([]byte, curveSize)
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copy(preMasterSecret[len(preMasterSecret)-len(xBytes):], xBytes)
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return preMasterSecret, nil
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}
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func (ka *ecdheKeyAgreement) processServerKeyExchange(config *Config, clientHello *clientHelloMsg, serverHello *serverHelloMsg, pk crypto.PublicKey, skx *serverKeyExchangeMsg) error {
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if len(skx.key) < 4 {
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return errServerKeyExchange
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}
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if skx.key[0] != 3 { // named curve
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return errors.New("tls: server selected unsupported curve")
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}
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ka.curveid = CurveID(skx.key[1])<<8 | CurveID(skx.key[2])
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publicLen := int(skx.key[3])
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if publicLen+4 > len(skx.key) {
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return errServerKeyExchange
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}
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serverECDHParams := skx.key[:4+publicLen]
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publicKey := serverECDHParams[4:]
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sig := skx.key[4+publicLen:]
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if len(sig) < 2 {
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return errServerKeyExchange
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}
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if ka.curveid == X25519 {
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if len(publicKey) != 32 {
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return errors.New("tls: bad X25519 public value")
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}
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ka.publicKey = publicKey
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} else {
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curve, ok := curveForCurveID(ka.curveid)
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if !ok {
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return errors.New("tls: server selected unsupported curve")
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}
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ka.x, ka.y = elliptic.Unmarshal(curve, publicKey) // Unmarshal also checks whether the given point is on the curve
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if ka.x == nil {
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return errServerKeyExchange
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}
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}
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var signatureAlgorithm SignatureScheme
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if ka.version >= VersionTLS12 {
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// handle SignatureAndHashAlgorithm
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signatureAlgorithm = SignatureScheme(sig[0])<<8 | SignatureScheme(sig[1])
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sig = sig[2:]
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if len(sig) < 2 {
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return errServerKeyExchange
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}
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}
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_, sigType, hashFunc, err := pickSignatureAlgorithm(pk, []SignatureScheme{signatureAlgorithm}, clientHello.supportedSignatureAlgorithms, ka.version)
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if err != nil {
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return err
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}
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if (sigType == signaturePKCS1v15 || sigType == signatureRSAPSS) != ka.isRSA {
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return errServerKeyExchange
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}
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sigLen := int(sig[0])<<8 | int(sig[1])
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if sigLen+2 != len(sig) {
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return errServerKeyExchange
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}
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sig = sig[2:]
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digest, err := hashForServerKeyExchange(sigType, hashFunc, ka.version, clientHello.random, serverHello.random, serverECDHParams)
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if err != nil {
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return err
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}
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return verifyHandshakeSignature(sigType, pk, hashFunc, digest, sig)
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}
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func (ka *ecdheKeyAgreement) generateClientKeyExchange(config *Config, clientHello *clientHelloMsg, pk crypto.PublicKey) ([]byte, *clientKeyExchangeMsg, error) {
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if ka.curveid == 0 {
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return nil, nil, errors.New("tls: missing ServerKeyExchange message")
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}
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var serialized, preMasterSecret []byte
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if ka.curveid == X25519 {
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var ourPublic, theirPublic, sharedKey, scalar [32]byte
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if _, err := io.ReadFull(config.rand(), scalar[:]); err != nil {
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return nil, nil, err
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}
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copy(theirPublic[:], ka.publicKey)
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curve25519.ScalarBaseMult(&ourPublic, &scalar)
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curve25519.ScalarMult(&sharedKey, &scalar, &theirPublic)
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serialized = ourPublic[:]
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preMasterSecret = sharedKey[:]
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} else {
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curve, ok := curveForCurveID(ka.curveid)
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if !ok {
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panic("internal error")
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}
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priv, mx, my, err := elliptic.GenerateKey(curve, config.rand())
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if err != nil {
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return nil, nil, err
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}
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x, _ := curve.ScalarMult(ka.x, ka.y, priv)
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preMasterSecret = make([]byte, (curve.Params().BitSize+7)>>3)
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xBytes := x.Bytes()
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copy(preMasterSecret[len(preMasterSecret)-len(xBytes):], xBytes)
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serialized = elliptic.Marshal(curve, mx, my)
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}
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ckx := new(clientKeyExchangeMsg)
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ckx.ciphertext = make([]byte, 1+len(serialized))
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ckx.ciphertext[0] = byte(len(serialized))
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copy(ckx.ciphertext[1:], serialized)
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return preMasterSecret, ckx, nil
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}
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