crypto/internal/mlkem768: make Decapsulate a method

This will make it easier to support multiple sizes if needed.

Change-Id: I47495559fdbbf678fd98421ad6cb28172e5c810d
Reviewed-on: https://go-review.googlesource.com/c/go/+/621977
Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
Reviewed-by: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>

diff --git a/src/crypto/internal/mlkem768/mlkem768.go b/src/crypto/internal/mlkem768/mlkem768.go
index 527c93ffe36f4099202274d59f8c8797498731f9..0daf3594466de6ef5c45639678bbf6702a7a1b26 100644 (file)
--- a/src/crypto/internal/mlkem768/mlkem768.go
+++ b/src/crypto/internal/mlkem768/mlkem768.go
@@ -320,7 +320,7 @@ func pkeEncrypt(cc *[CiphertextSize]byte, ex *encryptionKey, m *[messageSize]byt
 // If the ciphertext is not valid, Decapsulate returns an error.
 //
 // The shared key must be kept secret.
-func Decapsulate(dk *DecapsulationKey, ciphertext []byte) (sharedKey []byte, err error) {
+func (dk *DecapsulationKey) Decapsulate(ciphertext []byte) (sharedKey []byte, err error) {
        if len(ciphertext) != CiphertextSize {
                return nil, errors.New("mlkem768: invalid ciphertext length")
        }

diff --git a/src/crypto/internal/mlkem768/mlkem768_test.go b/src/crypto/internal/mlkem768/mlkem768_test.go
index 7d32805b2f711d697d6bda99fe5c663b7ef2b4e1..5d129e11dfd0f74acba11a4ebffb9aeb1248b1c1 100644 (file)
--- a/src/crypto/internal/mlkem768/mlkem768_test.go
+++ b/src/crypto/internal/mlkem768/mlkem768_test.go
@@ -206,7 +206,7 @@ func TestRoundTrip(t *testing.T) {
        if err != nil {
                t.Fatal(err)
        }
-       Kd, err := Decapsulate(dk, c)
+       Kd, err := dk.Decapsulate(c)
        if err != nil {
                t.Fatal(err)
        }
@@ -263,14 +263,14 @@ func TestBadLengths(t *testing.T) {
        }
 
        for i := 0; i < len(c)-1; i++ {
-               if _, err := Decapsulate(dk, c[:i]); err == nil {
+               if _, err := dk.Decapsulate(c[:i]); err == nil {
                        t.Errorf("expected error for c length %d", i)
                }
        }
        cLong := c
        for i := 0; i < 100; i++ {
                cLong = append(cLong, 0)
-               if _, err := Decapsulate(dk, cLong); err == nil {
+               if _, err := dk.Decapsulate(cLong); err == nil {
                        t.Errorf("expected error for c length %d", len(cLong))
                }
        }
@@ -315,7 +315,7 @@ func TestAccumulated(t *testing.T) {
                o.Write(ct)
                o.Write(k)
 
-               kk, err := Decapsulate(dk, ct)
+               kk, err := dk.Decapsulate(ct)
                if err != nil {
                        t.Fatal(err)
                }
@@ -324,7 +324,7 @@ func TestAccumulated(t *testing.T) {
                }
 
                s.Read(ct1)
-               k1, err := Decapsulate(dk, ct1)
+               k1, err := dk.Decapsulate(ct1)
                if err != nil {
                        t.Fatal(err)
                }
@@ -408,7 +408,7 @@ func BenchmarkRoundTrip(b *testing.B) {
                        ekS := dkS.EncapsulationKey()
                        sink ^= ekS[0]
 
-                       Ks, err := Decapsulate(dk, c)
+                       Ks, err := dk.Decapsulate(c)
                        if err != nil {
                                b.Fatal(err)
                        }

diff --git a/src/crypto/tls/key_schedule.go b/src/crypto/tls/key_schedule.go
index 9c76ebe36702a770fed972303604822e24adaab8..e8ee9ce9c2febd5a8ca3e0791c44a48094f5b708 100644 (file)
--- a/src/crypto/tls/key_schedule.go
+++ b/src/crypto/tls/key_schedule.go
@@ -59,7 +59,7 @@ type keySharePrivateKeys struct {
 
 // kyberDecapsulate implements decapsulation according to Kyber Round 3.
 func kyberDecapsulate(dk *mlkem768.DecapsulationKey, c []byte) ([]byte, error) {
-       K, err := mlkem768.Decapsulate(dk, c)
+       K, err := dk.Decapsulate(c)
        if err != nil {
                return nil, err
        }