golang实现aes-cbc-256加密解密功能

// NewCipher creates and returns a new cipher.Block.
// The key argument should be the AES key,
// either 16, 24, or 32 bytes to select
// AES-128, AES-192, or AES-256.
func NewCipher(key []byte) (cipher.Block, error) {
   k := len(key)
   switch k {
   default:
      return nil, KeySizeError(k)
   case 16, 24, 32:
      break
   }
   return newCipher(key)
}

const BlockSize = 16  //你一眼就看到这么帅的我
type aesCipherAsm struct {
   aesCipher
}
var useAsm = cipherhw.AESGCMSupport()
func newCipher(key []byte) (cipher.Block, error) {
   if !useAsm {
      return newCipherGeneric(key)
   }
   n := len(key) + 28
   c := aesCipherAsm{aesCipher{make([]uint32, n), make([]uint32, n)}}
   rounds := 10
   switch len(key) {
   case 128 / 8:
      rounds = 10
   case 192 / 8:
      rounds = 12
   case 256 / 8:
      rounds = 14
   }
   expandKeyAsm(rounds, &key[0], &c.enc[0], &c.dec[0])
   if hasGCMAsm() {
      return &aesCipherGCM{c}, nil
   }
   return &c, nil
}
func (c *aesCipherAsm) BlockSize() int { return BlockSize }
func (c *aesCipherAsm) Encrypt(dst, src []byte) {
   if len(src) < BlockSize {
      panic("crypto/aes: input not full block")
   }
   if len(dst) < BlockSize {
      panic("crypto/aes: output not full block")
   }
   encryptBlockAsm(len(c.enc)/4-1, &c.enc[0], &dst[0], &src[0])
}
func (c *aesCipherAsm) Decrypt(dst, src []byte) {
   if len(src) < BlockSize {
      panic("crypto/aes: input not full block")
   }
   if len(dst) < BlockSize {
      panic("crypto/aes: output not full block")
   }
   decryptBlockAsm(len(c.dec)/4-1, &c.dec[0], &dst[0], &src[0])
}

//加密实现
TEXT ·encryptBlockAsm(SB),NOSPLIT,$0
    MOVQ nr+0(FP), CX
    666...
Lenc256:
    MOVUPS 0(AX), X1
    666...
Lenc196:
    MOVUPS 0(AX), X1
    666...
Lenc128:
    MOVUPS 0(AX), X1
    666..
    RET
//解密实现
// func decryptBlockAsm(nr int, xk *uint32, dst, src *byte)
TEXT ·decryptBlockAsm(SB),NOSPLIT,$0
    MOVQ nr+0(FP), CX
    666...
Ldec256:
    MOVUPS 0(AX), X1
    666...
Ldec196:
    MOVUPS 0(AX), X1
    666...
Ldec128:
    MOVUPS 0(AX), X1
    666...
    RET
//通过key和iv初始化加密解密所需的数据结构
// func expandKeyAsm(nr int, key *byte, enc, dec *uint32) {
// Note that round keys are stored in uint128 fORMat, not uint32
TEXT ·expandKeyAsm(SB),NOSPLIT,$0
    MOVQ nr+0(FP), CX
    JE Lexp_enc196   //完全不知道是两个什么鬼命令
    JB Lexp_enc128   //同上，所以说是两个鬼命令
Lexp_enc256:
    MOVUPS 16(AX), X2
    666...

//获取加密key长度
func geTKEySize(size int) int {
   for _, val := range keySizes {
      if size <= val {
         return val
      }
   }
   return BLOCK_SIZE
}

//c语言实现
static byte bmul(byte x, byte y)
{        
   if (x && y)
      return ptab[(ltab[x] + ltab[y]) % 255];
   else
      return 0;
}
bmul(200,200) == 145
//go语言实现
func bmul(x, y byte) byte {
   if x > 0 && y > 0 {
      return ptab[(ltab[x]+ltab[y])%255]
   }
   return 0
}
bmul(200,200) == 144