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Update deprecated curve25519 functions and defend against low-order point attacks

This commit is contained in:
Andy Wang 2020-12-21 16:37:33 +00:00
parent 0d3f8dd27f
commit de0daac123
No known key found for this signature in database
GPG Key ID: 181B49F9F38F3374
5 changed files with 29 additions and 11 deletions
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12
internal/client/auth.go
View File

@ -4,6 +4,7 @@ import (
"encoding/binary"
"github.com/cbeuw/Cloak/internal/common"
"github.com/cbeuw/Cloak/internal/ecdh"
log "github.com/sirupsen/logrus"
)
const (
@ -26,7 +27,10 @@ func makeAuthenticationPayload(authInfo AuthInfo) (ret authenticationPayload, sh
| 16 bytes | 12 bytes | 1 byte | 8 bytes | 4 bytes | 1 byte | 6 bytes |
+----------+----------------+---------------------+-------------+--------------+--------+------------+
*/
ephPv, ephPub, _ := ecdh.GenerateKey(authInfo.WorldState.Rand)
ephPv, ephPub, err := ecdh.GenerateKey(authInfo.WorldState.Rand)
if err != nil {
log.Panicf("failed to generate ephemeral key pair: %v", err)
}
copy(ret.randPubKey[:], ecdh.Marshal(ephPub))
plaintext := make([]byte, 48)
@ -40,7 +44,11 @@ func makeAuthenticationPayload(authInfo AuthInfo) (ret authenticationPayload, sh
plaintext[41] |= UNORDERED_FLAG
}
copy(sharedSecret[:], ecdh.GenerateSharedSecret(ephPv, authInfo.ServerPubKey))
secret, err := ecdh.GenerateSharedSecret(ephPv, authInfo.ServerPubKey)
if err != nil {
log.Panicf("error in generating shared secret: %v", err)
}
copy(sharedSecret[:], secret)
ciphertextWithTag, _ := common.AESGCMEncrypt(ret.randPubKey[:12], sharedSecret[:], plaintext)
copy(ret.ciphertextWithTag[:], ciphertextWithTag[:])
return

8
internal/ecdh/curve25519.go
View File

@ -68,13 +68,11 @@ func Unmarshal(data []byte) (crypto.PublicKey, bool) {
return &pub, true
}
func GenerateSharedSecret(privKey crypto.PrivateKey, pubKey crypto.PublicKey) []byte {
var priv, pub, secret *[32]byte
func GenerateSharedSecret(privKey crypto.PrivateKey, pubKey crypto.PublicKey) ([]byte, error) {
var priv, pub *[32]byte
priv = privKey.(*[32]byte)
pub = pubKey.(*[32]byte)
secret = new([32]byte)
curve25519.ScalarMult(secret, priv, pub)
return secret[:]
return curve25519.X25519(priv[:], pub[:])
}

4
internal/ecdh/curve25519_test.go
View File

@ -90,11 +90,11 @@ func testECDH(t testing.TB) {
t.Fatalf("Unmarshal does not work")
}
secret1 = GenerateSharedSecret(privKey1, pubKey2)
secret1, err = GenerateSharedSecret(privKey1, pubKey2)
if err != nil {
t.Error(err)
}
secret2 = GenerateSharedSecret(privKey2, pubKey1)
secret2, err = GenerateSharedSecret(privKey2, pubKey1)
if err != nil {
t.Error(err)
}

8
internal/server/TLS.go
View File

@ -79,7 +79,13 @@ func (TLS) unmarshalClientHello(ch *ClientHello, staticPv crypto.PrivateKey) (fr
return
}
copy(fragments.sharedSecret[:], ecdh.GenerateSharedSecret(staticPv, ephPub))
var sharedSecret []byte
sharedSecret, err = ecdh.GenerateSharedSecret(staticPv, ephPub)
if err != nil {
return
}
copy(fragments.sharedSecret[:], sharedSecret)
var keyShare []byte
keyShare, err = parseKeyShare(ch.extensions[[2]byte{0x00, 0x33}])
if err != nil {

8
internal/server/websocket.go
View File

@ -84,7 +84,13 @@ func (WebSocket) unmarshalHidden(hidden []byte, staticPv crypto.PrivateKey) (fra
return
}
copy(fragments.sharedSecret[:], ecdh.GenerateSharedSecret(staticPv, ephPub))
var sharedSecret []byte
sharedSecret, err = ecdh.GenerateSharedSecret(staticPv, ephPub)
if err != nil {
return
}
copy(fragments.sharedSecret[:], sharedSecret)
if len(hidden[32:]) != 64 {
err = fmt.Errorf("%v: %v", ErrCiphertextLength, len(hidden[32:]))