crypto/internal/mlkem768: add EncapsulationKey type

Change-Id: I3feacb044caa15ac9bbfc11f5d90bebf8a505510
Reviewed-on: https://go-review.googlesource.com/c/go/+/621980
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Filippo Valsorda 2024-10-21 14:30:46 +02:00 committed by Gopher Robot
parent 3e14e25cf0
commit 5a893857d7
3 changed files with 8 additions and 7 deletions

View file

@ -164,7 +164,7 @@ func (c *Conn) makeClientHello() (*clientHelloMsg, *keySharePrivateKeys, *echCon
if _, err := io.ReadFull(config.rand(), seed); err != nil {
return nil, nil, nil, err
}
keyShareKeys.kyber, err = mlkem768.NewKeyFromSeed(seed)
keyShareKeys.kyber, err = mlkem768.NewDecapsulationKey(seed)
if err != nil {
return nil, nil, nil, err
}
@ -174,7 +174,7 @@ func (c *Conn) makeClientHello() (*clientHelloMsg, *keySharePrivateKeys, *echCon
// both, as allowed by draft-ietf-tls-hybrid-design-09, Section 3.2.
hello.keyShares = []keyShare{
{group: x25519Kyber768Draft00, data: append(keyShareKeys.ecdhe.PublicKey().Bytes(),
keyShareKeys.kyber.EncapsulationKey()...)},
keyShareKeys.kyber.EncapsulationKey().Bytes()...)},
{group: X25519, data: keyShareKeys.ecdhe.PublicKey().Bytes()},
}
} else {

View file

@ -63,19 +63,20 @@ func kyberDecapsulate(dk *mlkem768.DecapsulationKey, c []byte) ([]byte, error) {
if err != nil {
return nil, err
}
return kyberSharedSecret(K, c), nil
return kyberSharedSecret(c, K), nil
}
// kyberEncapsulate implements encapsulation according to Kyber Round 3.
func kyberEncapsulate(ek []byte) (c, ss []byte, err error) {
c, ss, err = mlkem768.Encapsulate(ek)
k, err := mlkem768.NewEncapsulationKey(ek)
if err != nil {
return nil, nil, err
}
return c, kyberSharedSecret(ss, c), nil
c, ss = k.Encapsulate()
return c, kyberSharedSecret(c, ss), nil
}
func kyberSharedSecret(K, c []byte) []byte {
func kyberSharedSecret(c, K []byte) []byte {
// Package mlkem768 implements ML-KEM, which compared to Kyber removed a
// final hashing step. Compute SHAKE-256(K || SHA3-256(c), 32) to match Kyber.
// See https://words.filippo.io/mlkem768/#bonus-track-using-a-ml-kem-implementation-as-kyber-v3.

View file

@ -124,7 +124,7 @@ func TestKyberEncapsulate(t *testing.T) {
if err != nil {
t.Fatal(err)
}
ct, ss, err := kyberEncapsulate(dk.EncapsulationKey())
ct, ss, err := kyberEncapsulate(dk.EncapsulationKey().Bytes())
if err != nil {
t.Fatal(err)
}