chore: vendor

vendor/github.com/ProtonMail/go-crypto/openpgp/internal/ecc/x448.go

@@ -0,0 +1,107 @@
+// Package ecc implements a generic interface for ECDH, ECDSA, and EdDSA.
+package ecc
+
+import (
+	"crypto/subtle"
+	"io"
+
+	"github.com/ProtonMail/go-crypto/openpgp/errors"
+	x448lib "github.com/cloudflare/circl/dh/x448"
+)
+
+type x448 struct{}
+
+func NewX448() *x448 {
+	return &x448{}
+}
+
+func (c *x448) GetCurveName() string {
+	return "x448"
+}
+
+// MarshalBytePoint encodes the public point from native format, adding the prefix.
+// See https://datatracker.ietf.org/doc/html/draft-ietf-openpgp-crypto-refresh-06#section-5.5.5.6
+func (c *x448) MarshalBytePoint(point []byte) []byte {
+	return append([]byte{0x40}, point...)
+}
+
+// UnmarshalBytePoint decodes a point from prefixed format to native.
+// See https://datatracker.ietf.org/doc/html/draft-ietf-openpgp-crypto-refresh-06#section-5.5.5.6
+func (c *x448) UnmarshalBytePoint(point []byte) []byte {
+	if len(point) != x448lib.Size+1 {
+		return nil
+	}
+
+	return point[1:]
+}
+
+// MarshalByteSecret encoded a scalar from native format to prefixed.
+// See https://datatracker.ietf.org/doc/html/draft-ietf-openpgp-crypto-refresh-06#section-5.5.5.6.1.2
+func (c *x448) MarshalByteSecret(d []byte) []byte {
+	return append([]byte{0x40}, d...)
+}
+
+// UnmarshalByteSecret decodes a scalar from prefixed format to native.
+// See https://datatracker.ietf.org/doc/html/draft-ietf-openpgp-crypto-refresh-06#section-5.5.5.6.1.2
+func (c *x448) UnmarshalByteSecret(d []byte) []byte {
+	if len(d) != x448lib.Size+1 {
+		return nil
+	}
+
+	// Store without prefix
+	return d[1:]
+}
+
+func (c *x448) generateKeyPairBytes(rand io.Reader) (sk, pk x448lib.Key, err error) {
+	if _, err = rand.Read(sk[:]); err != nil {
+		return
+	}
+
+	x448lib.KeyGen(&pk, &sk)
+	return
+}
+
+func (c *x448) GenerateECDH(rand io.Reader) (point []byte, secret []byte, err error) {
+	priv, pub, err := c.generateKeyPairBytes(rand)
+	if err != nil {
+		return
+	}
+
+	return pub[:], priv[:], nil
+}
+
+func (c *x448) Encaps(rand io.Reader, point []byte) (ephemeral, sharedSecret []byte, err error) {
+	var pk, ss x448lib.Key
+	seed, e, err := c.generateKeyPairBytes(rand)
+	if err != nil {
+		return nil, nil, err
+	}
+	copy(pk[:], point)
+	x448lib.Shared(&ss, &seed, &pk)
+
+	return e[:], ss[:], nil
+}
+
+func (c *x448) Decaps(ephemeral, secret []byte) (sharedSecret []byte, err error) {
+	var ss, sk, e x448lib.Key
+
+	copy(sk[:], secret)
+	copy(e[:], ephemeral)
+	x448lib.Shared(&ss, &sk, &e)
+
+	return ss[:], nil
+}
+
+func (c *x448) ValidateECDH(point []byte, secret []byte) error {
+	var sk, pk, expectedPk x448lib.Key
+
+	copy(pk[:], point)
+	copy(sk[:], secret)
+	x448lib.KeyGen(&expectedPk, &sk)
+
+	if subtle.ConstantTimeCompare(expectedPk[:], pk[:]) == 0 {
+		return errors.KeyInvalidError("ecc: invalid curve25519 public point")
+	}
+
+	return nil
+}