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sm4: code refactor for block

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Sun Yimin 2024-01-31 13:08:51 +08:00 committed by GitHub
parent aaabb09dac
commit 19636d09c1
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
3 changed files with 22 additions and 24 deletions
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42
sm4/block.go
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@ -8,9 +8,8 @@ import (
// Encrypt one block from src into dst, using the expanded key xk.
func encryptBlockGo(xk []uint32, dst, src []byte) {
_ = src[15] // early bounds check
dst = dst[:16] // early bounds check
_ = xk[31] // bounds check elimination hint
_ = src[15] // early bounds check
_ = xk[31] // bounds check elimination hint
var b0, b1, b2, b3 uint32
b0 = binary.BigEndian.Uint32(src[0:4])
@ -18,11 +17,13 @@ func encryptBlockGo(xk []uint32, dst, src []byte) {
b2 = binary.BigEndian.Uint32(src[8:12])
b3 = binary.BigEndian.Uint32(src[12:16])
// First round uses s-box directly and T transformation.
b0 ^= t(b1 ^ b2 ^ b3 ^ xk[0])
b1 ^= t(b2 ^ b3 ^ b0 ^ xk[1])
b2 ^= t(b3 ^ b0 ^ b1 ^ xk[2])
b3 ^= t(b0 ^ b1 ^ b2 ^ xk[3])
// Middle rounds (unroll loop) uses precomputed tables.
b0 ^= precompute_t(b1 ^ b2 ^ b3 ^ xk[4])
b1 ^= precompute_t(b2 ^ b3 ^ b0 ^ xk[5])
b2 ^= precompute_t(b3 ^ b0 ^ b1 ^ xk[6])
@ -53,15 +54,17 @@ func encryptBlockGo(xk []uint32, dst, src []byte) {
b2 ^= precompute_t(b3 ^ b0 ^ b1 ^ xk[26])
b3 ^= precompute_t(b0 ^ b1 ^ b2 ^ xk[27])
// Last round uses s-box directly and and T transformation to produce output.
b0 ^= t(b1 ^ b2 ^ b3 ^ xk[28])
b1 ^= t(b2 ^ b3 ^ b0 ^ xk[29])
b2 ^= t(b3 ^ b0 ^ b1 ^ xk[30])
b3 ^= t(b0 ^ b1 ^ b2 ^ xk[31])
binary.BigEndian.PutUint32(dst[:], b3)
binary.BigEndian.PutUint32(dst[4:], b2)
binary.BigEndian.PutUint32(dst[8:], b1)
binary.BigEndian.PutUint32(dst[12:], b0)
_ = dst[15] // early bounds check
binary.BigEndian.PutUint32(dst[0:4], b3)
binary.BigEndian.PutUint32(dst[4:8], b2)
binary.BigEndian.PutUint32(dst[8:12], b1)
binary.BigEndian.PutUint32(dst[12:16], b0)
}
// Key expansion algorithm.
@ -149,19 +152,14 @@ func expandKeyGo(key []byte, enc, dec []uint32) {
enc[31], dec[0] = b3, b3
}
// Decrypt one block from src into dst, using the expanded key xk.
func decryptBlockGo(xk []uint32, dst, src []byte) {
encryptBlockGo(xk, dst, src)
}
// T
func t(in uint32) uint32 {
var b uint32
b = uint32(sbox[in&0xff])
b |= uint32(sbox[(in>>8)&0xff]) << 8
b |= uint32(sbox[(in>>16)&0xff]) << 16
b |= uint32(sbox[(in>>24)&0xff]) << 24
b |= uint32(sbox[in>>8&0xff]) << 8
b |= uint32(sbox[in>>16&0xff]) << 16
b |= uint32(sbox[in>>24&0xff]) << 24
// L
return b ^ (b<<2 | b>>30) ^ (b<<10 | b>>22) ^ (b<<18 | b>>14) ^ (b<<24 | b>>8)
@ -172,17 +170,17 @@ func t2(in uint32) uint32 {
var b uint32
b = uint32(sbox[in&0xff])
b |= uint32(sbox[(in>>8)&0xff]) << 8
b |= uint32(sbox[(in>>16)&0xff]) << 16
b |= uint32(sbox[(in>>24)&0xff]) << 24
b |= uint32(sbox[in>>8&0xff]) << 8
b |= uint32(sbox[in>>16&0xff]) << 16
b |= uint32(sbox[in>>24&0xff]) << 24
// L2
return b ^ (b<<13 | b>>19) ^ (b<<23 | b>>9)
}
func precompute_t(in uint32) uint32 {
return sbox_t0[byte(in>>24)] ^
sbox_t1[byte(in>>16)] ^
sbox_t2[byte(in>>8)] ^
sbox_t3[byte(in)]
return sbox_t0[in>>24&0xff] ^
sbox_t1[in>>16&0xff] ^
sbox_t2[in>>8&0xff] ^
sbox_t3[in&0xff]
}

2
sm4/cipher.go
View File

@ -65,5 +65,5 @@ func (c *sm4Cipher) Decrypt(dst, src []byte) {
if alias.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
panic("sm4: invalid buffer overlap")
}
decryptBlockGo(c.dec, dst, src)
encryptBlockGo(c.dec, dst, src)
}

2
sm4/cipher_asm.go
View File

@ -91,7 +91,7 @@ func (c *sm4CipherAsm) Decrypt(dst, src []byte) {
if useAESNI4SingleBlock {
encryptBlockAsm(&c.dec[0], &dst[0], &src[0], INST_AES)
} else {
decryptBlockGo(c.dec, dst, src)
encryptBlockGo(c.dec, dst, src)
}
}