ref: 8bc69a872883224675a55db51ac8f60ab5ed9e5a
dir: /third_party/boringssl/src/ssl/test/runner/prf.go/
// 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 runner
import (
"crypto"
"crypto/hmac"
"crypto/md5"
"crypto/sha1"
"crypto/sha256"
"encoding"
"hash"
"golang.org/x/crypto/hkdf"
)
// copyHash returns a copy of |h|, which must be an instance of |hashType|.
func copyHash(h hash.Hash, hash crypto.Hash) hash.Hash {
// While hash.Hash is not copyable, the documentation says all standard
// library hash.Hash implementations implement BinaryMarshaler and
// BinaryUnmarshaler interfaces.
m, ok := h.(encoding.BinaryMarshaler)
if !ok {
panic("hash did not implement encoding.BinaryMarshaler")
}
data, err := m.MarshalBinary()
if err != nil {
panic(err)
}
ret := hash.New()
u, ok := ret.(encoding.BinaryUnmarshaler)
if !ok {
panic("hash did not implement BinaryUnmarshaler")
}
if err := u.UnmarshalBinary(data); err != nil {
panic(err)
}
return ret
}
// 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)
todo := len(b)
if j+todo > len(result) {
todo = len(result) - j
}
copy(result[j:j+todo], b)
j += todo
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)
}
}
const (
tlsRandomLength = 32 // Length of a random nonce in TLS 1.1.
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 extendedMasterSecretLabel = []byte("extended master secret")
var keyExpansionLabel = []byte("key expansion")
var clientFinishedLabel = []byte("client finished")
var serverFinishedLabel = []byte("server finished")
var finishedLabel = []byte("finished")
var channelIDLabel = []byte("TLS Channel ID signature\x00")
var channelIDResumeLabel = []byte("Resumption\x00")
func prfForVersion(version uint16, suite *cipherSuite) func(result, secret, label, seed []byte) {
switch version {
case VersionTLS10, VersionTLS11:
return prf10
case VersionTLS12:
return prf12(suite.hash().New)
}
panic("unknown version")
}
// masterFromPreMasterSecret generates the master secret from the pre-master
// secret. See http://tools.ietf.org/html/rfc5246#section-8.1
func masterFromPreMasterSecret(version uint16, suite *cipherSuite, preMasterSecret, clientRandom, serverRandom []byte) []byte {
var seed [tlsRandomLength * 2]byte
copy(seed[0:len(clientRandom)], clientRandom)
copy(seed[len(clientRandom):], serverRandom)
masterSecret := make([]byte, masterSecretLength)
prfForVersion(version, suite)(masterSecret, preMasterSecret, masterSecretLabel, seed[0:])
return masterSecret
}
// extendedMasterFromPreMasterSecret generates the master secret from the
// pre-master secret when the Triple Handshake fix is in effect. See
// https://tools.ietf.org/html/rfc7627
func extendedMasterFromPreMasterSecret(version uint16, suite *cipherSuite, preMasterSecret []byte, h finishedHash) []byte {
masterSecret := make([]byte, masterSecretLength)
prfForVersion(version, suite)(masterSecret, preMasterSecret, extendedMasterSecretLabel, h.Sum())
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) {
var seed [tlsRandomLength * 2]byte
copy(seed[0:len(clientRandom)], serverRandom)
copy(seed[len(serverRandom):], clientRandom)
n := 2*macLen + 2*keyLen + 2*ivLen
keyMaterial := make([]byte, n)
prfForVersion(version, suite)(keyMaterial, masterSecret, keyExpansionLabel, seed[0:])
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
}
func newFinishedHash(wireVersion uint16, isDTLS bool, cipherSuite *cipherSuite) finishedHash {
version, ok := wireToVersion(wireVersion, isDTLS)
if !ok {
panic("unknown version")
}
var ret finishedHash
if version >= VersionTLS12 {
ret.hash = cipherSuite.hash().New()
if version == VersionTLS12 {
ret.prf = prf12(cipherSuite.hash().New)
} else {
ret.secret = make([]byte, ret.hash.Size())
}
} else {
ret.hash = sha1.New()
ret.md5 = md5.New()
ret.prf = prf10
}
ret.suite = cipherSuite
ret.buffer = []byte{}
ret.version = version
ret.wireVersion = wireVersion
ret.isDTLS = isDTLS
return ret
}
// A finishedHash calculates the hash of a set of handshake messages suitable
// for including in a Finished message.
type finishedHash struct {
suite *cipherSuite
// hash maintains a running hash of handshake messages. In TLS 1.2 and up,
// the hash is determined from suite.hash(). In TLS 1.0 and 1.1, this is the
// SHA-1 half of the MD5/SHA-1 concatenation.
hash hash.Hash
// md5 is the MD5 half of the TLS 1.0 and 1.1 MD5/SHA1 concatenation.
md5 hash.Hash
// In TLS 1.2, a full buffer is required.
buffer []byte
version uint16
wireVersion uint16
isDTLS bool
prf func(result, secret, label, seed []byte)
// secret, in TLS 1.3, is the running input secret.
secret []byte
}
func (h *finishedHash) UpdateForHelloRetryRequest() {
data := newByteBuilder()
data.addU8(typeMessageHash)
data.addU24(h.hash.Size())
data.addBytes(h.Sum())
h.hash = h.suite.hash().New()
if h.buffer != nil {
h.buffer = []byte{}
}
h.Write(data.finish())
}
func (h *finishedHash) Write(msg []byte) (n int, err error) {
h.hash.Write(msg)
if h.version < VersionTLS12 {
h.md5.Write(msg)
}
if h.buffer != nil {
h.buffer = append(h.buffer, msg...)
}
return len(msg), nil
}
// WriteHandshake appends |msg| to the hash, which must be a serialized
// handshake message with a TLS header. In DTLS, the header is rewritten to a
// DTLS header with |seqno| as the sequence number.
func (h *finishedHash) WriteHandshake(msg []byte, seqno uint16) {
if h.isDTLS {
// This is somewhat hacky. DTLS hashes a slightly different format.
// First, the TLS header.
h.Write(msg[:4])
// Then the sequence number and reassembled fragment offset (always 0).
h.Write([]byte{byte(seqno >> 8), byte(seqno), 0, 0, 0})
// Then the reassembled fragment (always equal to the message length).
h.Write(msg[1:4])
// And then the message body.
h.Write(msg[4:])
} else {
h.Write(msg)
}
}
func (h finishedHash) Sum() []byte {
if h.version >= VersionTLS12 {
return h.hash.Sum(nil)
}
out := make([]byte, 0, md5.Size+sha1.Size)
out = h.md5.Sum(out)
return h.hash.Sum(out)
}
// clientSum returns the contents of the verify_data member of a client's
// Finished message.
func (h finishedHash) clientSum(baseKey []byte) []byte {
if h.version < VersionTLS13 {
out := make([]byte, finishedVerifyLength)
h.prf(out, baseKey, clientFinishedLabel, h.Sum())
return out
}
clientFinishedKey := hkdfExpandLabel(h.suite.hash(), baseKey, finishedLabel, nil, h.hash.Size())
finishedHMAC := hmac.New(h.suite.hash().New, clientFinishedKey)
finishedHMAC.Write(h.appendContextHashes(nil))
return finishedHMAC.Sum(nil)
}
// serverSum returns the contents of the verify_data member of a server's
// Finished message.
func (h finishedHash) serverSum(baseKey []byte) []byte {
if h.version < VersionTLS13 {
out := make([]byte, finishedVerifyLength)
h.prf(out, baseKey, serverFinishedLabel, h.Sum())
return out
}
serverFinishedKey := hkdfExpandLabel(h.suite.hash(), baseKey, finishedLabel, nil, h.hash.Size())
finishedHMAC := hmac.New(h.suite.hash().New, serverFinishedKey)
finishedHMAC.Write(h.appendContextHashes(nil))
return finishedHMAC.Sum(nil)
}
// hashForChannelID returns the hash to be signed for TLS Channel
// ID. If a resumption, resumeHash has the previous handshake
// hash. Otherwise, it is nil.
func (h finishedHash) hashForChannelID(resumeHash []byte) []byte {
hash := sha256.New()
hash.Write(channelIDLabel)
if resumeHash != nil {
hash.Write(channelIDResumeLabel)
hash.Write(resumeHash)
}
hash.Write(h.Sum())
return hash.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
}
// zeroSecretTLS13 returns the default all zeros secret for TLS 1.3, used when a
// given secret is not available in the handshake. See RFC 8446, section 7.1.
func (h *finishedHash) zeroSecret() []byte {
return make([]byte, h.hash.Size())
}
// addEntropy incorporates ikm into the running TLS 1.3 secret with HKDF-Expand.
func (h *finishedHash) addEntropy(ikm []byte) {
h.secret = hkdf.Extract(h.suite.hash().New, ikm, h.secret)
}
func (h *finishedHash) nextSecret() {
h.secret = hkdfExpandLabel(h.suite.hash(), h.secret, []byte("derived"), h.suite.hash().New().Sum(nil), h.hash.Size())
}
// hkdfExpandLabel implements TLS 1.3's HKDF-Expand-Label function, as defined
// in section 7.1 of RFC 8446.
func hkdfExpandLabel(hash crypto.Hash, secret, label, hashValue []byte, length int) []byte {
if len(label) > 255 || len(hashValue) > 255 {
panic("hkdfExpandLabel: label or hashValue too long")
}
versionLabel := []byte("tls13 ")
hkdfLabel := make([]byte, 3+len(versionLabel)+len(label)+1+len(hashValue))
x := hkdfLabel
x[0] = byte(length >> 8)
x[1] = byte(length)
x[2] = byte(len(versionLabel) + len(label))
x = x[3:]
copy(x, versionLabel)
x = x[len(versionLabel):]
copy(x, label)
x = x[len(label):]
x[0] = byte(len(hashValue))
copy(x[1:], hashValue)
ret := make([]byte, length)
if n, err := hkdf.Expand(hash.New, secret, hkdfLabel).Read(ret); err != nil || n != length {
panic("hkdfExpandLabel: hkdf.Expand unexpectedly failed")
}
return ret
}
// appendContextHashes returns the concatenation of the handshake hash and the
// resumption context hash, as used in TLS 1.3.
func (h *finishedHash) appendContextHashes(b []byte) []byte {
b = h.hash.Sum(b)
return b
}
var (
externalPSKBinderLabel = []byte("ext binder")
resumptionPSKBinderLabel = []byte("res binder")
earlyTrafficLabel = []byte("c e traffic")
clientHandshakeTrafficLabel = []byte("c hs traffic")
serverHandshakeTrafficLabel = []byte("s hs traffic")
clientApplicationTrafficLabel = []byte("c ap traffic")
serverApplicationTrafficLabel = []byte("s ap traffic")
applicationTrafficLabel = []byte("traffic upd")
earlyExporterLabel = []byte("e exp master")
exporterLabel = []byte("exp master")
resumptionLabel = []byte("res master")
resumptionPSKLabel = []byte("resumption")
echAcceptConfirmationLabel = []byte("ech accept confirmation")
echAcceptConfirmationHRRLabel = []byte("hrr ech accept confirmation")
)
// deriveSecret implements TLS 1.3's Derive-Secret function, as defined in
// section 7.1 of RFC8446.
func (h *finishedHash) deriveSecret(label []byte) []byte {
return hkdfExpandLabel(h.suite.hash(), h.secret, label, h.appendContextHashes(nil), h.hash.Size())
}
// echConfirmation computes the ECH accept confirmation signal, as defined in
// sections 7.2 and 7.2.1 of draft-ietf-tls-esni-13. The transcript hash is
// computed by concatenating |h| with |extraMessages|.
func (h *finishedHash) echAcceptConfirmation(clientRandom, label, extraMessages []byte) []byte {
secret := hkdf.Extract(h.suite.hash().New, clientRandom, h.zeroSecret())
hashCopy := copyHash(h.hash, h.suite.hash())
hashCopy.Write(extraMessages)
return hkdfExpandLabel(h.suite.hash(), secret, label, hashCopy.Sum(nil), echAcceptConfirmationLength)
}
// The following are context strings for CertificateVerify in TLS 1.3.
var (
clientCertificateVerifyContextTLS13 = []byte("TLS 1.3, client CertificateVerify")
serverCertificateVerifyContextTLS13 = []byte("TLS 1.3, server CertificateVerify")
channelIDContextTLS13 = []byte("TLS 1.3, Channel ID")
)
// certificateVerifyMessage returns the input to be signed for CertificateVerify
// in TLS 1.3.
func (h *finishedHash) certificateVerifyInput(context []byte) []byte {
const paddingLen = 64
b := make([]byte, paddingLen, paddingLen+len(context)+1+2*h.hash.Size())
for i := 0; i < paddingLen; i++ {
b[i] = 32
}
b = append(b, context...)
b = append(b, 0)
b = h.appendContextHashes(b)
return b
}
type trafficDirection int
const (
clientWrite trafficDirection = iota
serverWrite
)
var (
keyTLS13 = []byte("key")
ivTLS13 = []byte("iv")
)
// deriveTrafficAEAD derives traffic keys and constructs an AEAD given a traffic
// secret.
func deriveTrafficAEAD(version uint16, suite *cipherSuite, secret []byte, side trafficDirection) interface{} {
key := hkdfExpandLabel(suite.hash(), secret, keyTLS13, nil, suite.keyLen)
iv := hkdfExpandLabel(suite.hash(), secret, ivTLS13, nil, suite.ivLen(version))
return suite.aead(version, key, iv)
}
func updateTrafficSecret(hash crypto.Hash, version uint16, secret []byte) []byte {
return hkdfExpandLabel(hash, secret, applicationTrafficLabel, nil, hash.Size())
}
func computePSKBinder(psk []byte, version uint16, label []byte, cipherSuite *cipherSuite, clientHello, helloRetryRequest, truncatedHello []byte) []byte {
finishedHash := newFinishedHash(version, false, cipherSuite)
finishedHash.addEntropy(psk)
binderKey := finishedHash.deriveSecret(label)
finishedHash.Write(clientHello)
if len(helloRetryRequest) != 0 {
finishedHash.UpdateForHelloRetryRequest()
}
finishedHash.Write(helloRetryRequest)
finishedHash.Write(truncatedHello)
return finishedHash.clientSum(binderKey)
}
func deriveSessionPSK(suite *cipherSuite, version uint16, masterSecret []byte, nonce []byte) []byte {
hash := suite.hash()
return hkdfExpandLabel(hash, masterSecret, resumptionPSKLabel, nonce, hash.Size())
}