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sm4: finetune bounds check

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Sun Yimin 2023-06-05 14:32:15 +08:00 committed by GitHub
parent f3a5d48ed8
commit 57d800767b
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 27 additions and 15 deletions
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36
sm4/block.go
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@ -11,8 +11,10 @@ type convert func(uint32) uint32
// Encrypt one block from src into dst, using the expanded key xk. // Encrypt one block from src into dst, using the expanded key xk.
func encryptBlockGo(xk []uint32, dst, src []byte) { func encryptBlockGo(xk []uint32, dst, src []byte) {
_ = src[15] // early bounds check _ = src[15] // early bounds check
_ = dst[15] // early bounds check dst = dst[:16] // early bounds check
_ = xk[31] // bounds check elimination hint
var b0, b1, b2, b3 uint32 var b0, b1, b2, b3 uint32
b0 = binary.BigEndian.Uint32(src[0:4]) b0 = binary.BigEndian.Uint32(src[0:4])
b1 = binary.BigEndian.Uint32(src[4:8]) b1 = binary.BigEndian.Uint32(src[4:8])
@ -68,16 +70,22 @@ func encryptBlockGo(xk []uint32, dst, src []byte) {
// Key expansion algorithm. // Key expansion algorithm.
func expandKeyGo(key []byte, enc, dec []uint32) { func expandKeyGo(key []byte, enc, dec []uint32) {
// Encryption key setup. // Encryption key setup.
enc = enc[:rounds-1]
var i int var i int
var mk []uint32 var mk [4]uint32
var k [rounds + 4]uint32 var k [rounds + 4]uint32
nk := len(key) / 4
mk = make([]uint32, nk)
for i = 0; i < nk; i++ {
mk[i] = binary.BigEndian.Uint32(key[4*i:])
k[i] = mk[i] ^ fk[i]
}
key = key[:KeySize]
mk[0] = binary.BigEndian.Uint32(key)
k[0] = mk[0] ^ fk[0]
mk[1] = binary.BigEndian.Uint32(key[4:])
k[1] = mk[1] ^ fk[1]
mk[2] = binary.BigEndian.Uint32(key[8:])
k[2] = mk[2] ^ fk[2]
mk[3] = binary.BigEndian.Uint32(key[12:])
k[3] = mk[3] ^ fk[3]
_ = enc[rounds-1]
for i = 0; i < rounds; i++ { for i = 0; i < rounds; i++ {
k[i+4] = k[i] ^ t2(k[i+1]^k[i+2]^k[i+3]^ck[i]) k[i+4] = k[i] ^ t2(k[i+1]^k[i+2]^k[i+3]^ck[i])
enc[i] = k[i+4] enc[i] = k[i+4]
@ -87,6 +95,8 @@ func expandKeyGo(key []byte, enc, dec []uint32) {
if dec == nil { if dec == nil {
return return
} }
dec = dec[:rounds-1]
for i = 0; i < rounds; i++ { for i = 0; i < rounds; i++ {
dec[i] = enc[rounds-1-i] dec[i] = enc[rounds-1-i]
} }
@ -97,12 +107,12 @@ func decryptBlockGo(xk []uint32, dst, src []byte) {
encryptBlockGo(xk, dst, src) encryptBlockGo(xk, dst, src)
} }
//L(B) // L(B)
func l(b uint32) uint32 { func l(b uint32) uint32 {
return b ^ bits.RotateLeft32(b, 2) ^ bits.RotateLeft32(b, 10) ^ bits.RotateLeft32(b, 18) ^ bits.RotateLeft32(b, 24) return b ^ bits.RotateLeft32(b, 2) ^ bits.RotateLeft32(b, 10) ^ bits.RotateLeft32(b, 18) ^ bits.RotateLeft32(b, 24)
} }
//L'(B) // L'(B)
func l2(b uint32) uint32 { func l2(b uint32) uint32 {
return b ^ bits.RotateLeft32(b, 13) ^ bits.RotateLeft32(b, 23) return b ^ bits.RotateLeft32(b, 13) ^ bits.RotateLeft32(b, 23)
} }
@ -116,12 +126,12 @@ func _t(in uint32, fn convert) uint32 {
return fn(binary.BigEndian.Uint32(bytes[:])) return fn(binary.BigEndian.Uint32(bytes[:]))
} }
//T // T
func t(in uint32) uint32 { func t(in uint32) uint32 {
return _t(in, l) return _t(in, l)
} }
//T' // T'
func t2(in uint32) uint32 { func t2(in uint32) uint32 {
return _t(in, l2) return _t(in, l2)
} }

4
sm4/cbc_cipher_asm.go
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@ -78,8 +78,8 @@ func (x *cbc) CryptBlocks(dst, src []byte) {
for start > 0 { for start > 0 {
x.b.DecryptBlocks(temp, src[start:end]) x.b.DecryptBlocks(temp, src[start:end])
copy(batchSrc, src[start-BlockSize:]) subtle.XORBytes(temp, temp, src[start-BlockSize:end-BlockSize])
subtle.XORBytes(dst[start:], temp, batchSrc) copy(dst[start:], temp)
end = start end = start
start -= x.b.blocksSize start -= x.b.blocksSize
} }

2
sm4/const.go
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@ -214,3 +214,5 @@ var ck = [32]uint32{
var fk = [4]uint32{ var fk = [4]uint32{
0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc, 0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc,
} }
const KeySize = 16