mldsa: supports prehash dsa

mldsa/prehash.go

@@ -0,0 +1,92 @@
+// Copyright 2025 Sun Yimin. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.24
+
+package mldsa
+
+import (
+	"crypto/sha256"
+	"crypto/sha3"
+	"crypto/sha512"
+	"encoding/asn1"
+	"errors"
+	"hash"
+
+	"github.com/emmansun/gmsm/sm3"
+)
+
+var (
+	// Digest Algorithms
+	OIDDigestAlgorithmSHA256   = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 1}
+	OIDDigestAlgorithmSHA512   = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 3}
+	OIDDigestAlgorithmSHA3_256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 8}
+	OIDDigestAlgorithmSHA3_384 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 9}
+	OIDDigestAlgorithmSHA3_512 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 10}
+	OIDDigestAlgorithmSHAKE128 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 11}
+	OIDDigestAlgorithmSHAKE256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 12}
+	OIDDigestAlgorithmSM3      = asn1.ObjectIdentifier{1, 2, 156, 10197, 1, 401}
+)
+
+var ErrUnsupportedDigestAlgorithm = errors.New("mldsa: unsupported digest algorithm")
+
+type xofHashAdapter struct {
+	*sha3.SHAKE
+	size int
+}
+
+func (h *xofHashAdapter) Write(p []byte) (n int, err error) {
+	return h.SHAKE.Write(p)
+}
+
+func (h *xofHashAdapter) Reset() {
+	h.SHAKE.Reset()
+}
+
+func (h *xofHashAdapter) Size() int {
+	return h.size
+}
+
+func (x *xofHashAdapter) BlockSize() int {
+	return x.SHAKE.BlockSize()
+}
+
+func (x *xofHashAdapter) Sum(b []byte) []byte {
+	buf := make([]byte, x.size)
+	x.Read(buf)
+	return append(b, buf...)
+}
+
+func getHashByOID(oid asn1.ObjectIdentifier) (hash.Hash, error) {
+	switch {
+	case oid.Equal(OIDDigestAlgorithmSHA256):
+		return sha256.New(), nil
+	case oid.Equal(OIDDigestAlgorithmSHA512):
+		return sha512.New(), nil
+	case oid.Equal(OIDDigestAlgorithmSHA3_256):
+		return sha3.New256(), nil
+	case oid.Equal(OIDDigestAlgorithmSHA3_384):
+		return sha3.New384(), nil
+	case oid.Equal(OIDDigestAlgorithmSHA3_512):
+		return sha3.New512(), nil
+	case oid.Equal(OIDDigestAlgorithmSHAKE128):
+		return &xofHashAdapter{sha3.NewSHAKE128(), 32}, nil
+	case oid.Equal(OIDDigestAlgorithmSHAKE256):
+		return &xofHashAdapter{sha3.NewSHAKE256(), 64}, nil
+	case oid.Equal(OIDDigestAlgorithmSM3):
+		return sm3.New(), nil
+	default:
+		return nil, ErrUnsupportedDigestAlgorithm
+	}
+}
+
+func preHash(oid asn1.ObjectIdentifier, data []byte) ([]byte, error) {
+	h, err := getHashByOID(oid)
+	if err != nil {
+		return nil, err
+	}
+	h.Write(data)
+	oidBytes, _ := asn1.Marshal(oid)
+	return h.Sum(oidBytes), nil
+}