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Commit 2fe9a5a3 authored by Adam Langley's avatar Adam Langley
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crypto/tls: support AES-GCM. 

AES-GCM is the only current TLS ciphersuite that doesn't have
cryptographic weaknesses (RC4), nor major construction issues (CBC mode
ciphers) and has some deployment (i.e. not-CCM).

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13249044
parent c4aa9c5c
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Showing with 154 additions and 35 deletions
src/pkg/crypto/tls/cipher_suites.go
View file @ 2fe9a5a3
......@@ -49,22 +49,25 @@ type cipherSuite struct {
elliptic bool
cipher func(key, iv []byte, isRead bool) interface{}
mac func(version uint16, macKey []byte) macFunction
aead func(key, fixedNonce []byte) cipher.AEAD
}
var cipherSuites = []*cipherSuite{
// Ciphersuite order is chosen so that ECDHE comes before plain RSA
// and RC4 comes before AES (because of the Lucky13 attack).
{TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, true, cipherRC4, macSHA1},
{TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, true, cipherRC4, macSHA1},
{TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, true, cipherAES, macSHA1},
{TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, true, cipherAES, macSHA1},
{TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, true, cipherAES, macSHA1},
{TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, true, cipherAES, macSHA1},
{TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, false, cipherRC4, macSHA1},
{TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, false, cipherAES, macSHA1},
{TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, false, cipherAES, macSHA1},
{TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, true, cipher3DES, macSHA1},
{TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, false, cipher3DES, macSHA1},
{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, true, nil, nil, aeadAESGCM},
{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, true, nil, nil, aeadAESGCM},
{TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, true, cipherRC4, macSHA1, nil},
{TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, true, cipherRC4, macSHA1, nil},
{TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, true, cipherAES, macSHA1, nil},
{TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, true, cipherAES, macSHA1, nil},
{TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, true, cipherAES, macSHA1, nil},
{TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, true, cipherAES, macSHA1, nil},
{TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, false, cipherRC4, macSHA1, nil},
{TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, false, cipherAES, macSHA1, nil},
{TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, false, cipherAES, macSHA1, nil},
{TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, true, cipher3DES, macSHA1, nil},
{TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, false, cipher3DES, macSHA1, nil},
}
func cipherRC4(key, iv []byte, isRead bool) interface{} {
......@@ -106,6 +109,46 @@ type macFunction interface {
MAC(digestBuf, seq, header, data []byte) []byte
}
// fixedNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to
// each call.
type fixedNonceAEAD struct {
// sealNonce and openNonce are buffers where the larger nonce will be
// constructed. Since a seal and open operation may be running
// concurrently, there is a separate buffer for each.
sealNonce, openNonce []byte
aead cipher.AEAD
}
func (f *fixedNonceAEAD) NonceSize() int { return 8 }
func (f *fixedNonceAEAD) Overhead() int { return f.aead.Overhead() }
func (f *fixedNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
copy(f.sealNonce[len(f.sealNonce)-8:], nonce)
return f.aead.Seal(out, f.sealNonce, plaintext, additionalData)
}
func (f *fixedNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) {
copy(f.openNonce[len(f.openNonce)-8:], nonce)
return f.aead.Open(out, f.openNonce, plaintext, additionalData)
}
func aeadAESGCM(key, fixedNonce []byte) cipher.AEAD {
aes, err := aes.NewCipher(key)
if err != nil {
panic(err)
}
aead, err := cipher.NewGCM(aes)
if err != nil {
panic(err)
}
nonce1, nonce2 := make([]byte, 12), make([]byte, 12)
copy(nonce1, fixedNonce)
copy(nonce2, fixedNonce)
return &fixedNonceAEAD{nonce1, nonce2, aead}
}
// ssl30MAC implements the SSLv3 MAC function, as defined in
// www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 5.2.3.1
type ssl30MAC struct {
......@@ -197,15 +240,17 @@ func mutualCipherSuite(have []uint16, want uint16) *cipherSuite {
// 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_3DES_EDE_CBC_SHA uint16 = 0x000a
TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f
TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035
TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a
TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011
TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014
TLS_RSA_WITH_RC4_128_SHA uint16 = 0x0005
TLS_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0x000a
TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f
TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035
TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a
TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011
TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02f
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b
)
src/pkg/crypto/tls/conn.go
View file @ 2fe9a5a3
......@@ -146,6 +146,9 @@ func (hc *halfConn) changeCipherSpec() error {
hc.mac = hc.nextMac
hc.nextCipher = nil
hc.nextMac = nil
for i := range hc.seq {
hc.seq[i] = 0
}
return nil
}
......@@ -255,6 +258,26 @@ func (hc *halfConn) decrypt(b *block) (ok bool, prefixLen int, alertValue alert)
switch c := hc.cipher.(type) {
case cipher.Stream:
c.XORKeyStream(payload, payload)
case cipher.AEAD:
explicitIVLen = 8
if len(payload) < explicitIVLen {
return false, 0, alertBadRecordMAC
}
nonce := payload[:8]
payload = payload[8:]
var additionalData [13]byte
copy(additionalData[:], hc.seq[:])
copy(additionalData[8:], b.data[:3])
n := len(payload) - c.Overhead()
additionalData[11] = byte(n >> 8)
additionalData[12] = byte(n)
var err error
payload, err = c.Open(payload[:0], nonce, payload, additionalData[:])
if err != nil {
return false, 0, alertBadRecordMAC
}
b.resize(recordHeaderLen + explicitIVLen + len(payload))
case cbcMode:
blockSize := c.BlockSize()
if hc.version >= VersionTLS11 {
......@@ -305,13 +328,13 @@ func (hc *halfConn) decrypt(b *block) (ok bool, prefixLen int, alertValue alert)
b.resize(recordHeaderLen + explicitIVLen + n)
remoteMAC := payload[n:]
localMAC := hc.mac.MAC(hc.inDigestBuf, hc.seq[0:], b.data[:recordHeaderLen], payload[:n])
hc.incSeq()
if subtle.ConstantTimeCompare(localMAC, remoteMAC) != 1 || paddingGood != 255 {
return false, 0, alertBadRecordMAC
}
hc.inDigestBuf = localMAC
}
hc.incSeq()
return true, recordHeaderLen + explicitIVLen, 0
}
......@@ -338,7 +361,6 @@ func (hc *halfConn) encrypt(b *block, explicitIVLen int) (bool, alert) {
// mac
if hc.mac != nil {
mac := hc.mac.MAC(hc.outDigestBuf, hc.seq[0:], b.data[:recordHeaderLen], b.data[recordHeaderLen+explicitIVLen:])
hc.incSeq()
n := len(b.data)
b.resize(n + len(mac))
......@@ -353,6 +375,20 @@ func (hc *halfConn) encrypt(b *block, explicitIVLen int) (bool, alert) {
switch c := hc.cipher.(type) {
case cipher.Stream:
c.XORKeyStream(payload, payload)
case cipher.AEAD:
payloadLen := len(b.data) - recordHeaderLen - explicitIVLen
b.resize(len(b.data) + c.Overhead())
nonce := b.data[recordHeaderLen : recordHeaderLen+explicitIVLen]
payload := b.data[recordHeaderLen+explicitIVLen:]
payload = payload[:payloadLen]
var additionalData [13]byte
copy(additionalData[:], hc.seq[:])
copy(additionalData[8:], b.data[:3])
additionalData[11] = byte(payloadLen >> 8)
additionalData[12] = byte(payloadLen)
c.Seal(payload[:0], nonce, payload, additionalData[:])
case cbcMode:
blockSize := c.BlockSize()
if explicitIVLen > 0 {
......@@ -372,6 +408,7 @@ func (hc *halfConn) encrypt(b *block, explicitIVLen int) (bool, alert) {
n := len(b.data) - recordHeaderLen
b.data[3] = byte(n >> 8)
b.data[4] = byte(n)
hc.incSeq()
return true, 0
}
......@@ -660,6 +697,7 @@ func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) {
m = maxPlaintext
}
explicitIVLen := 0
explicitIVIsSeq := false
var cbc cbcMode
if c.out.version >= VersionTLS11 {
......@@ -668,6 +706,18 @@ func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) {
explicitIVLen = cbc.BlockSize()
}
}
if explicitIVLen == 0 {
if _, ok := c.out.cipher.(cipher.AEAD); ok {
explicitIVLen = 8
// The AES-GCM construction in TLS has an
// explicit nonce so that the nonce can be
// random. However, the nonce is only 8 bytes
// which is too small for a secure, random
// nonce. Therefore we use the sequence number
// as the nonce.
explicitIVIsSeq = true
}
}
b.resize(recordHeaderLen + explicitIVLen + m)
b.data[0] = byte(typ)
vers := c.vers
......@@ -682,8 +732,12 @@ func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) {
b.data[4] = byte(m)
if explicitIVLen > 0 {
explicitIV := b.data[recordHeaderLen : recordHeaderLen+explicitIVLen]
if _, err = io.ReadFull(c.config.rand(), explicitIV); err != nil {
break
if explicitIVIsSeq {
copy(explicitIV, c.out.seq[:])
} else {
if _, err = io.ReadFull(c.config.rand(), explicitIV); err != nil {
break
}
}
}
copy(b.data[recordHeaderLen+explicitIVLen:], data)
......
src/pkg/crypto/tls/handshake_client.go
View file @ 2fe9a5a3
......@@ -308,8 +308,14 @@ func (c *Conn) clientHandshake() error {
clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
keysFromMasterSecret(c.vers, masterSecret, hello.random, serverHello.random, suite.macLen, suite.keyLen, suite.ivLen)
clientCipher := suite.cipher(clientKey, clientIV, false /* not for reading */)
clientHash := suite.mac(c.vers, clientMAC)
var clientCipher interface{}
var clientHash macFunction
if suite.cipher != nil {
clientCipher = suite.cipher(clientKey, clientIV, false /* not for reading */)
clientHash = suite.mac(c.vers, clientMAC)
} else {
clientCipher = suite.aead(clientKey, clientIV)
}
c.out.prepareCipherSpec(c.vers, clientCipher, clientHash)
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
......@@ -329,8 +335,14 @@ func (c *Conn) clientHandshake() error {
finishedHash.Write(finished.marshal())
c.writeRecord(recordTypeHandshake, finished.marshal())
serverCipher := suite.cipher(serverKey, serverIV, true /* for reading */)
serverHash := suite.mac(c.vers, serverMAC)
var serverCipher interface{}
var serverHash macFunction
if suite.cipher != nil {
serverCipher = suite.cipher(serverKey, serverIV, true /* for reading */)
serverHash = suite.mac(c.vers, serverMAC)
} else {
serverCipher = suite.aead(serverKey, serverIV)
}
c.in.prepareCipherSpec(c.vers, serverCipher, serverHash)
c.readRecord(recordTypeChangeCipherSpec)
if err := c.error(); err != nil {
......
src/pkg/crypto/tls/handshake_server.go
View file @ 2fe9a5a3
......@@ -435,12 +435,20 @@ func (hs *serverHandshakeState) establishKeys() error {
clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
keysFromMasterSecret(c.vers, hs.masterSecret, hs.clientHello.random, hs.hello.random, hs.suite.macLen, hs.suite.keyLen, hs.suite.ivLen)
clientCipher := hs.suite.cipher(clientKey, clientIV, true /* for reading */)
clientHash := hs.suite.mac(c.vers, clientMAC)
c.in.prepareCipherSpec(c.vers, clientCipher, clientHash)
var clientCipher, serverCipher interface{}
var clientHash, serverHash macFunction
if hs.suite.aead == nil {
clientCipher = hs.suite.cipher(clientKey, clientIV, true /* for reading */)
clientHash = hs.suite.mac(c.vers, clientMAC)
serverCipher = hs.suite.cipher(serverKey, serverIV, false /* not for reading */)
serverHash = hs.suite.mac(c.vers, serverMAC)
} else {
clientCipher = hs.suite.aead(clientKey, clientIV)
serverCipher = hs.suite.aead(serverKey, serverIV)
}
serverCipher := hs.suite.cipher(serverKey, serverIV, false /* not for reading */)
serverHash := hs.suite.mac(c.vers, serverMAC)
c.in.prepareCipherSpec(c.vers, clientCipher, clientHash)
c.out.prepareCipherSpec(c.vers, serverCipher, serverHash)
return nil
......
src/pkg/crypto/tls/handshake_server_test.go
View file @ 2fe9a5a3
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