Implement bit-oriented SHA-1.

Author: tunabay

bitarray_sha1.go

@@ -0,0 +1,48 @@
+// Copyright (c) 2021 Hirotsuna Mizuno. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.
+
+package bitarray
+
+import (
+	//nolint:gosec // intentionally provided option
+	_ "crypto/sha1" // block()
+	"encoding/binary"
+	_ "unsafe" // linkname
+)
+
+// SHA1 returns the SHA-1 checksum of the bit array. It treats the bit array as
+// a bit-oriented message to compute the checksum as defined in RFC 3174.
+func (ba *BitArray) SHA1() [20]byte {
+	nBits := ba.Len()
+	buf := NewBuffer((nBits + 1 + 64 + 511) &^ 511)
+	buf.PutBitArrayAt(0, ba)
+	buf.PutBitAt(nBits, 1)
+	binary.BigEndian.PutUint64(buf.b[len(buf.b)-8:], uint64(nBits))
+
+	d := &sha1Digest{}
+	sha1Reset(d)
+	sha1Block(d, buf.b)
+
+	var sha1 [20]byte
+	for i := 0; i < 5; i++ {
+		binary.BigEndian.PutUint32(sha1[i<<2:], d.h[i])
+	}
+
+	return sha1
+}
+
+// crypto/sha1.digest
+// TODO: if possible, use crypto/sha1.digest directly
+type sha1Digest struct {
+	h   [5]uint32
+	x   [64]byte //nolint:structcheck,unused // for Reset()
+	nx  int      //nolint:structcheck,unused // for Reset()
+	len uint64   //nolint:structcheck,unused // for Reset()
+}
+
+//go:linkname sha1Block crypto/sha1.block
+func sha1Block(*sha1Digest, []byte)
+
+//go:linkname sha1Reset crypto/sha1.(*digest).Reset
+func sha1Reset(*sha1Digest)

bitarray_sha1_example_test.go

@@ -0,0 +1,23 @@
+// Copyright (c) 2021 Hirotsuna Mizuno. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.
+
+package bitarray_test
+
+import (
+	"fmt"
+
+	"github.com/tunabay/go-bitarray"
+)
+
+func ExampleBitArray_SHA1() {
+	ba1 := bitarray.MustParse("01")
+	ba2 := bitarray.MustParse("01001")
+
+	fmt.Printf("%x\n", ba1.SHA1())
+	fmt.Printf("%x\n", ba2.SHA1())
+
+	// Output:
+	// ec6b39952e1a3ec3ab3507185cf756181c84bbe2
+	// 3320540d1c28b96ddd03eee1b186a8f2ae883fbe
+}

bitarray_sha1_test.go

@@ -0,0 +1,31 @@
+// Copyright (c) 2021 Hirotsuna Mizuno. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.
+
+package bitarray_test
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestBitArray_SHA1_cavp(t *testing.T) {
+	test := func(name string) {
+		tcs, err := cavpTestCases(name)
+		if err != nil {
+			t.Fatalf("failed to load test cases: %s: %s", name, err)
+		}
+		for i, tc := range tcs {
+			got := tc.ba.SHA1()
+			if !bytes.Equal(got[:], tc.md) {
+				t.Errorf("unexpected hash: %s: #%d", name, i)
+				t.Logf("mlen: %d", tc.ba.Len())
+				t.Logf(" msg: %#b", tc.ba)
+				t.Logf(" got: %X", got)
+				t.Logf("want: %X", tc.md)
+			}
+		}
+	}
+	test("SHA1ShortMsg")
+	test("SHA1LongMsg")
+}