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vendor.github.com.refraction-networking.utls.prf.go Maven / Gradle / Ivy
// Copyright 2009 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/hmac"
"crypto/md5"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"errors"
"fmt"
"hash"
)
// Split a premaster secret in two as specified in RFC 4346, Section 5.
func splitPreMasterSecret(secret []byte) (s1, s2 []byte) {
s1 = secret[0 : (len(secret)+1)/2]
s2 = secret[len(secret)/2:]
return
}
// pHash implements the P_hash function, as defined in RFC 4346, Section 5.
func pHash(result, secret, seed []byte, hash func() hash.Hash) {
h := hmac.New(hash, secret)
h.Write(seed)
a := h.Sum(nil)
j := 0
for j < len(result) {
h.Reset()
h.Write(a)
h.Write(seed)
b := h.Sum(nil)
copy(result[j:], b)
j += len(b)
h.Reset()
h.Write(a)
a = h.Sum(nil)
}
}
// prf10 implements the TLS 1.0 pseudo-random function, as defined in RFC 2246, Section 5.
func prf10(result, secret, label, seed []byte) {
hashSHA1 := sha1.New
hashMD5 := md5.New
labelAndSeed := make([]byte, len(label)+len(seed))
copy(labelAndSeed, label)
copy(labelAndSeed[len(label):], seed)
s1, s2 := splitPreMasterSecret(secret)
pHash(result, s1, labelAndSeed, hashMD5)
result2 := make([]byte, len(result))
pHash(result2, s2, labelAndSeed, hashSHA1)
for i, b := range result2 {
result[i] ^= b
}
}
// prf12 implements the TLS 1.2 pseudo-random function, as defined in RFC 5246, Section 5.
func prf12(hashFunc func() hash.Hash) func(result, secret, label, seed []byte) {
return func(result, secret, label, seed []byte) {
labelAndSeed := make([]byte, len(label)+len(seed))
copy(labelAndSeed, label)
copy(labelAndSeed[len(label):], seed)
pHash(result, secret, labelAndSeed, hashFunc)
}
}
// prf30 implements the SSL 3.0 pseudo-random function, as defined in
// www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 6.
func prf30(result, secret, label, seed []byte) {
hashSHA1 := sha1.New()
hashMD5 := md5.New()
done := 0
i := 0
// RFC 5246 section 6.3 says that the largest PRF output needed is 128
// bytes. Since no more ciphersuites will be added to SSLv3, this will
// remain true. Each iteration gives us 16 bytes so 10 iterations will
// be sufficient.
var b [11]byte
for done < len(result) {
for j := 0; j <= i; j++ {
b[j] = 'A' + byte(i)
}
hashSHA1.Reset()
hashSHA1.Write(b[:i+1])
hashSHA1.Write(secret)
hashSHA1.Write(seed)
digest := hashSHA1.Sum(nil)
hashMD5.Reset()
hashMD5.Write(secret)
hashMD5.Write(digest)
done += copy(result[done:], hashMD5.Sum(nil))
i++
}
}
const (
masterSecretLength = 48 // Length of a master secret in TLS 1.1.
finishedVerifyLength = 12 // Length of verify_data in a Finished message.
)
var masterSecretLabel = []byte("master secret")
var keyExpansionLabel = []byte("key expansion")
var clientFinishedLabel = []byte("client finished")
var serverFinishedLabel = []byte("server finished")
func prfAndHashForVersion(version uint16, suite *cipherSuite) (func(result, secret, label, seed []byte), crypto.Hash) {
switch version {
case VersionSSL30:
return prf30, crypto.Hash(0)
case VersionTLS10, VersionTLS11:
return prf10, crypto.Hash(0)
case VersionTLS12:
if suite.flags&suiteSHA384 != 0 {
return prf12(sha512.New384), crypto.SHA384
}
return prf12(sha256.New), crypto.SHA256
default:
panic("unknown version")
}
}
func prfForVersion(version uint16, suite *cipherSuite) func(result, secret, label, seed []byte) {
prf, _ := prfAndHashForVersion(version, suite)
return prf
}
// masterFromPreMasterSecret generates the master secret from the pre-master
// secret. See RFC 5246, Section 8.1.
func masterFromPreMasterSecret(version uint16, suite *cipherSuite, preMasterSecret, clientRandom, serverRandom []byte) []byte {
seed := make([]byte, 0, len(clientRandom)+len(serverRandom))
seed = append(seed, clientRandom...)
seed = append(seed, serverRandom...)
masterSecret := make([]byte, masterSecretLength)
prfForVersion(version, suite)(masterSecret, preMasterSecret, masterSecretLabel, seed)
return masterSecret
}
// keysFromMasterSecret generates the connection keys from the master
// secret, given the lengths of the MAC key, cipher key and IV, as defined in
// RFC 2246, Section 6.3.
func keysFromMasterSecret(version uint16, suite *cipherSuite, masterSecret, clientRandom, serverRandom []byte, macLen, keyLen, ivLen int) (clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV []byte) {
seed := make([]byte, 0, len(serverRandom)+len(clientRandom))
seed = append(seed, serverRandom...)
seed = append(seed, clientRandom...)
n := 2*macLen + 2*keyLen + 2*ivLen
keyMaterial := make([]byte, n)
prfForVersion(version, suite)(keyMaterial, masterSecret, keyExpansionLabel, seed)
clientMAC = keyMaterial[:macLen]
keyMaterial = keyMaterial[macLen:]
serverMAC = keyMaterial[:macLen]
keyMaterial = keyMaterial[macLen:]
clientKey = keyMaterial[:keyLen]
keyMaterial = keyMaterial[keyLen:]
serverKey = keyMaterial[:keyLen]
keyMaterial = keyMaterial[keyLen:]
clientIV = keyMaterial[:ivLen]
keyMaterial = keyMaterial[ivLen:]
serverIV = keyMaterial[:ivLen]
return
}
// hashFromSignatureScheme returns the corresponding crypto.Hash for a given
// hash from a TLS SignatureScheme.
func hashFromSignatureScheme(signatureAlgorithm SignatureScheme) (crypto.Hash, error) {
switch signatureAlgorithm {
case PKCS1WithSHA1, ECDSAWithSHA1:
return crypto.SHA1, nil
case PKCS1WithSHA256, PSSWithSHA256, ECDSAWithP256AndSHA256:
return crypto.SHA256, nil
case PKCS1WithSHA384, PSSWithSHA384, ECDSAWithP384AndSHA384:
return crypto.SHA384, nil
case PKCS1WithSHA512, PSSWithSHA512, ECDSAWithP521AndSHA512:
return crypto.SHA512, nil
default:
return 0, fmt.Errorf("tls: unsupported signature algorithm: %#04x", signatureAlgorithm)
}
}
func newFinishedHash(version uint16, cipherSuite *cipherSuite) finishedHash {
var buffer []byte
if version == VersionSSL30 || version >= VersionTLS12 {
buffer = []byte{}
}
prf, hash := prfAndHashForVersion(version, cipherSuite)
if hash != 0 {
return finishedHash{hash.New(), hash.New(), nil, nil, buffer, version, prf}
}
return finishedHash{sha1.New(), sha1.New(), md5.New(), md5.New(), buffer, version, prf}
}
// A finishedHash calculates the hash of a set of handshake messages suitable
// for including in a Finished message.
type finishedHash struct {
client hash.Hash
server hash.Hash
// Prior to TLS 1.2, an additional MD5 hash is required.
clientMD5 hash.Hash
serverMD5 hash.Hash
// In TLS 1.2, a full buffer is sadly required.
buffer []byte
version uint16
prf func(result, secret, label, seed []byte)
}
func (h *finishedHash) Write(msg []byte) (n int, err error) {
h.client.Write(msg)
h.server.Write(msg)
if h.version < VersionTLS12 {
h.clientMD5.Write(msg)
h.serverMD5.Write(msg)
}
if h.buffer != nil {
h.buffer = append(h.buffer, msg...)
}
return len(msg), nil
}
func (h finishedHash) Sum() []byte {
if h.version >= VersionTLS12 {
return h.client.Sum(nil)
}
out := make([]byte, 0, md5.Size+sha1.Size)
out = h.clientMD5.Sum(out)
return h.client.Sum(out)
}
// finishedSum30 calculates the contents of the verify_data member of a SSLv3
// Finished message given the MD5 and SHA1 hashes of a set of handshake
// messages.
func finishedSum30(md5, sha1 hash.Hash, masterSecret []byte, magic []byte) []byte {
md5.Write(magic)
md5.Write(masterSecret)
md5.Write(ssl30Pad1[:])
md5Digest := md5.Sum(nil)
md5.Reset()
md5.Write(masterSecret)
md5.Write(ssl30Pad2[:])
md5.Write(md5Digest)
md5Digest = md5.Sum(nil)
sha1.Write(magic)
sha1.Write(masterSecret)
sha1.Write(ssl30Pad1[:40])
sha1Digest := sha1.Sum(nil)
sha1.Reset()
sha1.Write(masterSecret)
sha1.Write(ssl30Pad2[:40])
sha1.Write(sha1Digest)
sha1Digest = sha1.Sum(nil)
ret := make([]byte, len(md5Digest)+len(sha1Digest))
copy(ret, md5Digest)
copy(ret[len(md5Digest):], sha1Digest)
return ret
}
var ssl3ClientFinishedMagic = [4]byte{0x43, 0x4c, 0x4e, 0x54}
var ssl3ServerFinishedMagic = [4]byte{0x53, 0x52, 0x56, 0x52}
// clientSum returns the contents of the verify_data member of a client's
// Finished message.
func (h finishedHash) clientSum(masterSecret []byte) []byte {
if h.version == VersionSSL30 {
return finishedSum30(h.clientMD5, h.client, masterSecret, ssl3ClientFinishedMagic[:])
}
out := make([]byte, finishedVerifyLength)
h.prf(out, masterSecret, clientFinishedLabel, h.Sum())
return out
}
// serverSum returns the contents of the verify_data member of a server's
// Finished message.
func (h finishedHash) serverSum(masterSecret []byte) []byte {
if h.version == VersionSSL30 {
return finishedSum30(h.serverMD5, h.server, masterSecret, ssl3ServerFinishedMagic[:])
}
out := make([]byte, finishedVerifyLength)
h.prf(out, masterSecret, serverFinishedLabel, h.Sum())
return out
}
// hashForClientCertificate returns a digest over the handshake messages so far,
// suitable for signing by a TLS client certificate.
func (h finishedHash) hashForClientCertificate(sigType uint8, hashAlg crypto.Hash, masterSecret []byte) ([]byte, error) {
if (h.version == VersionSSL30 || h.version >= VersionTLS12) && h.buffer == nil {
panic("a handshake hash for a client-certificate was requested after discarding the handshake buffer")
}
if h.version == VersionSSL30 {
if sigType != signaturePKCS1v15 {
return nil, errors.New("tls: unsupported signature type for client certificate")
}
md5Hash := md5.New()
md5Hash.Write(h.buffer)
sha1Hash := sha1.New()
sha1Hash.Write(h.buffer)
return finishedSum30(md5Hash, sha1Hash, masterSecret, nil), nil
}
if h.version >= VersionTLS12 {
hash := hashAlg.New()
hash.Write(h.buffer)
return hash.Sum(nil), nil
}
if sigType == signatureECDSA {
return h.server.Sum(nil), nil
}
return h.Sum(), nil
}
// discardHandshakeBuffer is called when there is no more need to
// buffer the entirety of the handshake messages.
func (h *finishedHash) discardHandshakeBuffer() {
h.buffer = nil
}
// noExportedKeyingMaterial is used as a value of
// ConnectionState.ekm when renegotation is enabled and thus
// we wish to fail all key-material export requests.
func noExportedKeyingMaterial(label string, context []byte, length int) ([]byte, error) {
return nil, errors.New("crypto/tls: ExportKeyingMaterial is unavailable when renegotiation is enabled")
}
// ekmFromMasterSecret generates exported keying material as defined in RFC 5705.
func ekmFromMasterSecret(version uint16, suite *cipherSuite, masterSecret, clientRandom, serverRandom []byte) func(string, []byte, int) ([]byte, error) {
return func(label string, context []byte, length int) ([]byte, error) {
switch label {
case "client finished", "server finished", "master secret", "key expansion":
// These values are reserved and may not be used.
return nil, fmt.Errorf("crypto/tls: reserved ExportKeyingMaterial label: %s", label)
}
seedLen := len(serverRandom) + len(clientRandom)
if context != nil {
seedLen += 2 + len(context)
}
seed := make([]byte, 0, seedLen)
seed = append(seed, clientRandom...)
seed = append(seed, serverRandom...)
if context != nil {
if len(context) >= 1<<16 {
return nil, fmt.Errorf("crypto/tls: ExportKeyingMaterial context too long")
}
seed = append(seed, byte(len(context)>>8), byte(len(context)))
seed = append(seed, context...)
}
keyMaterial := make([]byte, length)
prfForVersion(version, suite)(keyMaterial, masterSecret, []byte(label), seed)
return keyMaterial, nil
}
}
