sm4: reduce allocations

sm4/block.go

@@ -7,9 +7,8 @@ import (
 )
 
 // Encrypt one block from src into dst, using the expanded key xk.
-func encryptBlockGo(xk []uint32, dst, src []byte) {
+func encryptBlockGo(xk *[rounds]uint32, dst, src []byte) {
 	_ = src[15] // early bounds check
-	_ = xk[31]  // bounds check elimination hint
 
 	var b0, b1, b2, b3 uint32
 	b0 = binary.BigEndian.Uint32(src[0:4])
@@ -68,10 +67,8 @@ func encryptBlockGo(xk []uint32, dst, src []byte) {
 }
 
 // Key expansion algorithm.
-func expandKeyGo(key []byte, enc, dec []uint32) {
+func expandKeyGo(key []byte, enc, dec *[rounds]uint32) {
 	// Encryption key setup.
-	enc = enc[:rounds]
-	dec = dec[:rounds]
 	key = key[:KeySize]
 	var b0, b1, b2, b3 uint32
 	b0 = binary.BigEndian.Uint32(key[:4]) ^ fk[0]

sm4/cipher.go

@@ -15,8 +15,8 @@ const rounds = 32
 
 // A cipher is an instance of SM4 encryption using a particular key.
 type sm4Cipher struct {
-	enc []uint32
-	dec []uint32
+	enc [rounds]uint32
+	dec [rounds]uint32
 }
 
 // NewCipher creates and returns a new cipher.Block.
@@ -35,9 +35,9 @@ func NewCipher(key []byte) (cipher.Block, error) {
 // newCipher creates and returns a new cipher.Block
 // implemented in pure Go.
 func newCipherGeneric(key []byte) (cipher.Block, error) {
-	c := sm4Cipher{make([]uint32, rounds), make([]uint32, rounds)}
-	expandKeyGo(key, c.enc, c.dec)
-	return &c, nil
+	c := &sm4Cipher{}
+	expandKeyGo(key, &c.enc, &c.dec)
+	return c, nil
 }
 
 func (c *sm4Cipher) BlockSize() int { return BlockSize }
@@ -52,7 +52,7 @@ func (c *sm4Cipher) Encrypt(dst, src []byte) {
 	if alias.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
 		panic("sm4: invalid buffer overlap")
 	}
-	encryptBlockGo(c.enc, dst, src)
+	encryptBlockGo(&c.enc, dst, src)
 }
 
 func (c *sm4Cipher) Decrypt(dst, src []byte) {
@@ -65,5 +65,5 @@ func (c *sm4Cipher) Decrypt(dst, src []byte) {
 	if alias.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
 		panic("sm4: invalid buffer overlap")
 	}
-	encryptBlockGo(c.dec, dst, src)
+	encryptBlockGo(&c.dec, dst, src)
 }

sm4/cipher_asm.go

@@ -51,12 +51,12 @@ func newCipher(key []byte) (cipher.Block, error) {
 	if useAVX2 {
 		blocks = 8
 	}
-	c := &sm4CipherAsm{sm4Cipher{make([]uint32, rounds), make([]uint32, rounds)}, blocks, blocks * BlockSize}
+	c := &sm4CipherGCM{sm4CipherAsm{sm4Cipher{}, blocks, blocks * BlockSize}}
 	expandKeyAsm(&key[0], &ck[0], &c.enc[0], &c.dec[0], INST_AES)
 	if supportsGFMUL {
-		return &sm4CipherGCM{c}, nil
+		return c, nil
 	}
-	return c, nil
+	return &c.sm4CipherAsm, nil
 }
 
 func (c *sm4CipherAsm) Concurrency() int { return c.batchBlocks }
@@ -74,7 +74,7 @@ func (c *sm4CipherAsm) Encrypt(dst, src []byte) {
 	if useAESNI4SingleBlock {
 		encryptBlockAsm(&c.enc[0], &dst[0], &src[0], INST_AES)
 	} else {
-		encryptBlockGo(c.enc, dst, src)
+		encryptBlockGo(&c.enc, dst, src)
 	}
 }
 
@@ -91,7 +91,7 @@ func (c *sm4CipherAsm) Decrypt(dst, src []byte) {
 	if useAESNI4SingleBlock {
 		encryptBlockAsm(&c.dec[0], &dst[0], &src[0], INST_AES)
 	} else {
-		encryptBlockGo(c.dec, dst, src)
+		encryptBlockGo(&c.dec, dst, src)
 	}
 }
 
@@ -129,6 +129,6 @@ func expandKey(key []byte, enc, dec []uint32) {
 	} else if supportsAES {
 		expandKeyAsm(&key[0], &ck[0], &enc[0], &dec[0], INST_AES)
 	} else {
-		expandKeyGo(key, enc, dec)
+		expandKeyGo(key, (*[rounds]uint32)(enc), (*[rounds]uint32)(dec))
 	}
 }

sm4/cipher_asm_fuzzy_test.go

@@ -13,8 +13,8 @@ import (
 func TestExpandKey(t *testing.T) {
 	key := make([]byte, 16)
 
-	encRes1 := make([]uint32, 32)
-	decRes1 := make([]uint32, 32)
+	var encRes1 [rounds]uint32
+	var decRes1 [rounds]uint32
 	encRes2 := make([]uint32, 32)
 	decRes2 := make([]uint32, 32)
 	var timeout *time.Timer
@@ -32,13 +32,13 @@ func TestExpandKey(t *testing.T) {
 		default:
 		}
 		io.ReadFull(rand.Reader, key)
-		expandKeyGo(key, encRes1, decRes1)
+		expandKeyGo(key, &encRes1, &decRes1)
 		expandKey(key, encRes2, decRes2)
-		if !reflect.DeepEqual(encRes1, encRes2) {
-			t.Errorf("expected=%x, result=%x\n", encRes1, encRes2)
+		if !reflect.DeepEqual(encRes1[:], encRes2) {
+			t.Errorf("expected=%x, result=%x\n", encRes1[:], encRes2)
 		}
-		if !reflect.DeepEqual(decRes1, decRes2) {
-			t.Errorf("expected=%x, result=%x\n", encRes1, encRes2)
+		if !reflect.DeepEqual(decRes1[:], decRes2) {
+			t.Errorf("expected=%x, result=%x\n", decRes1[:], decRes2)
 		}
 	}
 }

sm4/cipher_asm_test.go

@@ -25,7 +25,7 @@ func TestWithoutGFMUL(t *testing.T) {
 		if useAVX2 {
 			blocks = 8
 		}
-		c1 := &sm4CipherAsm{sm4Cipher{make([]uint32, rounds), make([]uint32, rounds)}, blocks, blocks * BlockSize}
+		c1 := &sm4CipherAsm{sm4Cipher{}, blocks, blocks * BlockSize}
 		expandKeyAsm(&key[0], &ck[0], &c1.enc[0], &c1.dec[0], INST_AES)
 		c = c1
 	}

sm4/cipher_generic.go

@@ -12,9 +12,3 @@ import "crypto/cipher"
 func newCipher(key []byte) (cipher.Block, error) {
 	return newCipherGeneric(key)
 }
-
-// expandKey is used by BenchmarkExpand and should
-// call an assembly implementation if one is available.
-func expandKey(key []byte, enc, dec []uint32) {
-	expandKeyGo(key, enc, dec)
-}

sm4/cipher_ni.go

@@ -13,12 +13,12 @@ type sm4CipherNI struct {
 }
 
 func newCipherNI(key []byte) (cipher.Block, error) {
-	c := &sm4CipherNI{sm4Cipher{make([]uint32, rounds), make([]uint32, rounds)}}
+	c := &sm4CipherNIGCM{sm4CipherNI{sm4Cipher{}}}
 	expandKeyAsm(&key[0], &ck[0], &c.enc[0], &c.dec[0], INST_SM4)
 	if supportsGFMUL {
-		return &sm4CipherNIGCM{c}, nil
+		return c, nil
 	}
-	return c, nil
+	return &c.sm4CipherNI, nil
 }
 
 func (c *sm4CipherNI) Encrypt(dst, src []byte) {

sm4/cipher_test.go

@@ -114,12 +114,3 @@ func BenchmarkDecrypt(b *testing.B) {
 		c.Decrypt(out, tt.out)
 	}
 }
-
-func BenchmarkExpand(b *testing.B) {
-	tt := encryptTests[0]
-	c := &sm4Cipher{make([]uint32, rounds), make([]uint32, rounds)}
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		expandKey(tt.key, c.enc, c.dec)
-	}
-}

sm4/sm4_gcm_asm.go

@@ -13,7 +13,7 @@ import (
 // will use the optimised implementation in this file when possible. Instances
 // of this type only exist when hasGCMAsm and hasAES returns true.
 type sm4CipherGCM struct {
-	*sm4CipherAsm
+	sm4CipherAsm
 }
 
 // Assert that sm4CipherGCM implements the gcmAble interface.
@@ -43,10 +43,10 @@ type gcmAsm struct {
 // called by crypto/cipher.NewGCM via the gcmAble interface.
 func (c *sm4CipherGCM) NewGCM(nonceSize, tagSize int) (cipher.AEAD, error) {
 	g := &gcmAsm{}
-	g.cipher = c.sm4CipherAsm
+	g.cipher = &c.sm4CipherAsm
 	g.nonceSize = nonceSize
 	g.tagSize = tagSize
-	gcmSm4Init(&g.bytesProductTable, g.cipher.enc, INST_AES)
+	gcmSm4Init(&g.bytesProductTable, g.cipher.enc[:], INST_AES)
 	return g, nil
 }
 
@@ -91,7 +91,7 @@ func (g *gcmAsm) Seal(dst, nonce, plaintext, data []byte) []byte {
 	}
 
 	if len(plaintext) > 0 {
-		gcmSm4Enc(&g.bytesProductTable, out, plaintext, &counter, &tagOut, g.cipher.enc)
+		gcmSm4Enc(&g.bytesProductTable, out, plaintext, &counter, &tagOut, g.cipher.enc[:])
 	}
 	gcmSm4Finish(&g.bytesProductTable, &tagMask, &tagOut, uint64(len(plaintext)), uint64(len(data)))
 	copy(out[len(plaintext):], tagOut[:])
@@ -144,7 +144,7 @@ func (g *gcmAsm) Open(dst, nonce, ciphertext, data []byte) ([]byte, error) {
 		panic("cipher: invalid buffer overlap")
 	}
 	if len(ciphertext) > 0 {
-		gcmSm4Dec(&g.bytesProductTable, out, ciphertext, &counter, &expectedTag, g.cipher.enc)
+		gcmSm4Dec(&g.bytesProductTable, out, ciphertext, &counter, &expectedTag, g.cipher.enc[:])
 	}
 	gcmSm4Finish(&g.bytesProductTable, &tagMask, &expectedTag, uint64(len(ciphertext)), uint64(len(data)))
 

sm4/sm4ni_gcm_asm.go

@@ -19,7 +19,7 @@ func gcmSm4niDec(productTable *[256]byte, dst, src []byte, ctr, T *[16]byte, rk
 // will use the optimised implementation in this file when possible. Instances
 // of this type only exist when hasGCMAsm and hasSM4 returns true.
 type sm4CipherNIGCM struct {
-	*sm4CipherNI
+	sm4CipherNI
 }
 
 // Assert that sm4CipherNIGCM implements the gcmAble interface.
@@ -44,10 +44,10 @@ func (g *gcmNI) Overhead() int {
 // called by crypto/cipher.NewGCM via the gcmAble interface.
 func (c *sm4CipherNIGCM) NewGCM(nonceSize, tagSize int) (cipher.AEAD, error) {
 	g := &gcmNI{}
-	g.cipher = c.sm4CipherNI
+	g.cipher = &c.sm4CipherNI
 	g.nonceSize = nonceSize
 	g.tagSize = tagSize
-	gcmSm4Init(&g.bytesProductTable, g.cipher.enc, INST_SM4)
+	gcmSm4Init(&g.bytesProductTable, g.cipher.enc[:], INST_SM4)
 	return g, nil
 }
 
@@ -84,7 +84,7 @@ func (g *gcmNI) Seal(dst, nonce, plaintext, data []byte) []byte {
 	}
 
 	if len(plaintext) > 0 {
-		gcmSm4niEnc(&g.bytesProductTable, out, plaintext, &counter, &tagOut, g.cipher.enc)
+		gcmSm4niEnc(&g.bytesProductTable, out, plaintext, &counter, &tagOut, g.cipher.enc[:])
 	}
 	gcmSm4Finish(&g.bytesProductTable, &tagMask, &tagOut, uint64(len(plaintext)), uint64(len(data)))
 	copy(out[len(plaintext):], tagOut[:])
@@ -137,7 +137,7 @@ func (g *gcmNI) Open(dst, nonce, ciphertext, data []byte) ([]byte, error) {
 		panic("cipher: invalid buffer overlap")
 	}
 	if len(ciphertext) > 0 {
-		gcmSm4niDec(&g.bytesProductTable, out, ciphertext, &counter, &expectedTag, g.cipher.enc)
+		gcmSm4niDec(&g.bytesProductTable, out, ciphertext, &counter, &expectedTag, g.cipher.enc[:])
 	}
 	gcmSm4Finish(&g.bytesProductTable, &tagMask, &expectedTag, uint64(len(ciphertext)), uint64(len(data)))