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fix: use cipher id to derive secret #192

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merged 1 commit into from
Sep 6, 2022
Merged

fix: use cipher id to derive secret #192

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14 changes: 7 additions & 7 deletions pkg/util/hkdf/hkdf.go
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ const (
)

// expandLabel implements HKDF-Expand-Label from RFC 8446, Section 7.1.
func expandLabel(secret []byte, label string, context []byte, length int) []byte {
func expandLabel(secret []byte, label string, context []byte, length int, cipherId uint32) []byte {
var hkdfLabel cryptobyte.Builder
hkdfLabel.AddUint16(uint16(length))
hkdfLabel.AddUint8LengthPrefixed(func(b *cryptobyte.Builder) {
Expand All @@ -63,13 +63,13 @@ func expandLabel(secret []byte, label string, context []byte, length int) []byte
out := make([]byte, length)

var transcript crypto.Hash
switch length {
case 32:
switch uint16(cipherId & 0x0000FFFF) {
case TLS_AES_128_GCM_SHA256, TLS_CHACHA20_POLY1305_SHA256:
transcript = crypto.SHA256
case 48:
case TLS_AES_256_GCM_SHA384:
transcript = crypto.SHA384
default:
panic(fmt.Sprintf("non-tls 1.3 hash found, length: %d", length))
panic(fmt.Sprintf("Unknown cipher: %d", cipherId))
}
n, err := hkdf.Expand(transcript.New, secret, hkdfLabel.BytesOrPanic()).Read(out)
if err != nil || n != length {
Expand All @@ -80,6 +80,6 @@ func expandLabel(secret []byte, label string, context []byte, length int) []byte

// from crypto/tls/key_schedule.go line 35
// DeriveSecret implements Derive-Secret from RFC 8446, Section 7.1.
func DeriveSecret(secret []byte, label string, transcript hash.Hash) []byte {
return expandLabel(secret, label, transcript.Sum(nil), transcript.Size())
func DeriveSecret(secret []byte, label string, transcript hash.Hash, cipherId uint32) []byte {
return expandLabel(secret, label, transcript.Sum(nil), transcript.Size(), cipherId)
}
23 changes: 9 additions & 14 deletions pkg/util/hkdf/hkdf_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -10,19 +10,14 @@ import (
func TestHkdf(t *testing.T) {
t.Log("TestHkdf")
//TODO
var cipher_id = 50336513
var cipherId uint32 = 50336513
var transcript hash.Hash
// test with different cipher_id
switch cipher_id & 0x0000FFFF {
case 0x1301:
t.Log("TLS_AES_128_GCM_SHA256")
// test with different cipherID
switch uint16(cipherId & 0x0000FFFF) {
case TLS_AES_128_GCM_SHA256, TLS_CHACHA20_POLY1305_SHA256:
transcript = crypto.SHA256.New()
case 0x1302:
t.Log("TLS_AES_256_GCM_SHA384")
case TLS_AES_256_GCM_SHA384:
transcript = crypto.SHA384.New()
case 0x1303:
t.Log("TLS_CHACHA20_POLY1305_SHA256")
transcript = crypto.SHA256.New()
default:
t.Log("Unknown cipher")
}
Expand All @@ -42,17 +37,17 @@ func TestHkdf(t *testing.T) {

transcript.Write(handshakeTrafficHash)
clientSecret := DeriveSecret(handshakeSecret,
ClientHandshakeTrafficLabel, transcript)
ClientHandshakeTrafficLabel, transcript, cipherId)
t.Logf("%s: %x", KeyLogLabelClientHandshake, clientSecret)

serverHandshakeSecret := DeriveSecret(handshakeSecret,
ServerHandshakeTrafficLabel, transcript)
ServerHandshakeTrafficLabel, transcript, cipherId)
t.Logf("%s: %x", KeyLogLabelServerHandshake, serverHandshakeSecret)

transcript = crypto.SHA256.New()
transcript.Write(serverFinishedHash)
trafficSecret := DeriveSecret(masterSecret,
ClientApplicationTrafficLabel, transcript)
ClientApplicationTrafficLabel, transcript, cipherId)
t.Logf("%s: %x", KeyLogLabelClientTraffic, trafficSecret)

transcript = crypto.SHA256.New()
Expand All @@ -63,7 +58,7 @@ func TestHkdf(t *testing.T) {
//hs.transcript.Write(finished.marshal())
transcript.Write(serverFinishedHash)
serverSecret := DeriveSecret(masterSecret,
ServerApplicationTrafficLabel, transcript)
ServerApplicationTrafficLabel, transcript, cipherId)
t.Logf("%s: %x", KeyLogLabelServerTraffic, serverSecret)

t.Logf("%s: %x", KeyLogLabelServerTraffic, exporterMasterSecret[:transcript.Size()])
Expand Down
8 changes: 4 additions & 4 deletions user/module/probe_openssl.go
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Original file line number Diff line number Diff line change
Expand Up @@ -500,18 +500,18 @@ func (this *MOpenSSLProbe) saveMasterSecret(secretEvent *event.MasterSecretEvent
return
}
transcript.Write(secretEvent.HandshakeTrafficHash[:])
clientSecret := hkdf.DeriveSecret(secretEvent.HandshakeSecret[:], hkdf.ClientHandshakeTrafficLabel, transcript)
clientSecret := hkdf.DeriveSecret(secretEvent.HandshakeSecret[:], hkdf.ClientHandshakeTrafficLabel, transcript, secretEvent.CipherId)
b = bytes.NewBufferString(fmt.Sprintf("%s %02x %02x\n", hkdf.KeyLogLabelClientHandshake, secretEvent.ClientRandom, clientSecret))

serverHandshakeSecret := hkdf.DeriveSecret(secretEvent.HandshakeSecret[:], hkdf.ServerHandshakeTrafficLabel, transcript)
serverHandshakeSecret := hkdf.DeriveSecret(secretEvent.HandshakeSecret[:], hkdf.ServerHandshakeTrafficLabel, transcript, secretEvent.CipherId)
b.WriteString(fmt.Sprintf("%s %02x %02x\n", hkdf.KeyLogLabelServerHandshake, secretEvent.ClientRandom, serverHandshakeSecret))

transcript.Reset()
transcript.Write(secretEvent.ServerFinishedHash[:])

trafficSecret := hkdf.DeriveSecret(secretEvent.MasterSecret[:], hkdf.ClientApplicationTrafficLabel, transcript)
trafficSecret := hkdf.DeriveSecret(secretEvent.MasterSecret[:], hkdf.ClientApplicationTrafficLabel, transcript, secretEvent.CipherId)
b.WriteString(fmt.Sprintf("%s %02x %02x\n", hkdf.KeyLogLabelClientTraffic, secretEvent.ClientRandom, trafficSecret))
serverSecret := hkdf.DeriveSecret(secretEvent.MasterSecret[:], hkdf.ServerApplicationTrafficLabel, transcript)
serverSecret := hkdf.DeriveSecret(secretEvent.MasterSecret[:], hkdf.ServerApplicationTrafficLabel, transcript, secretEvent.CipherId)
b.WriteString(fmt.Sprintf("%s %02x %02x\n", hkdf.KeyLogLabelServerTraffic, secretEvent.ClientRandom, serverSecret))

// TODO MasterSecret sum
Expand Down