SM4 研究与实现

文章目录

SM4

标准号：GB/T 32907-2016

SM4 分组对称加密算法，分组长度128位， 密钥长度128位； 实现参考论文，讲解的非常详细；以下列举几个易错点

• 基于密钥扩展轮密钥，在传入密钥时就可以确定
• 解密和加密都是一样流程，区别在于密钥；解密轮密钥是加密轮密钥的逆序

•                                <                         <                         <                         符号的含义                              <<< 符号的含义                  <<<符号的含义，该符号表示32位循环左移; 代码表示如下
  

funcrol32(x uint32, n int)uint32{return(x << n)|((x &0xffffffff)>>(32- n))}

实现

SM4和AES很类似，保持在golang语言实现的统一性； 可参考golang aes 实现结构和逻辑; https://github.com/golang/go/blob/go1.17.13/src/crypto/aes/cipher.go#L32

目录结构

cryptox/sm4/     
              |-------const.go                     常量定义和常量公式定义      
              |-------sm4.go                       SM4实现源文件            
              |-------sm4_test.go               SM4单元测试             
              |-------block.go                      SM4数字签名生成逻辑

代码实现

const.go

package sm4

// GB/T 32907-2016// http://c.gb688.cn/bzgk/gb/showGb?type=online&hcno=7803DE42D3BC5E80B0C3E5D8E873D56Aconst BlockSize =16// GB/T 32907-2016 SBoxvar sbox =[256]byte{0xd6,0x90,0xe9,0xfe,0xcc,0xe1,0x3d,0xb7,0x16,0xb6,0x14,0xc2,0x28,0xfb,0x2c,0x05,0x2b,0x67,0x9a,0x76,0x2a,0xbe,0x04,0xc3,0xaa,0x44,0x13,0x26,0x49,0x86,0x06,0x99,0x9c,0x42,0x50,0xf4,0x91,0xef,0x98,0x7a,0x33,0x54,0x0b,0x43,0xed,0xcf,0xac,0x62,0xe4,0xb3,0x1c,0xa9,0xc9,0x08,0xe8,0x95,0x80,0xdf,0x94,0xfa,0x75,0x8f,0x3f,0xa6,0x47,0x07,0xa7,0xfc,0xf3,0x73,0x17,0xba,0x83,0x59,0x3c,0x19,0xe6,0x85,0x4f,0xa8,0x68,0x6b,0x81,0xb2,0x71,0x64,0xda,0x8b,0xf8,0xeb,0x0f,0x4b,0x70,0x56,0x9d,0x35,0x1e,0x24,0x0e,0x5e,0x63,0x58,0xd1,0xa2,0x25,0x22,0x7c,0x3b,0x01,0x21,0x78,0x87,0xd4,0x00,0x46,0x57,0x9f,0xd3,0x27,0x52,0x4c,0x36,0x02,0xe7,0xa0,0xc4,0xc8,0x9e,0xea,0xbf,0x8a,0xd2,0x40,0xc7,0x38,0xb5,0xa3,0xf7,0xf2,0xce,0xf9,0x61,0x15,0xa1,0xe0,0xae,0x5d,0xa4,0x9b,0x34,0x1a,0x55,0xad,0x93,0x32,0x30,0xf5,0x8c,0xb1,0xe3,0x1d,0xf6,0xe2,0x2e,0x82,0x66,0xca,0x60,0xc0,0x29,0x23,0xab,0x0d,0x53,0x4e,0x6f,0xd5,0xdb,0x37,0x45,0xde,0xfd,0x8e,0x2f,0x03,0xff,0x6a,0x72,0x6d,0x6c,0x5b,0x51,0x8d,0x1b,0xaf,0x92,0xbb,0xdd,0xbc,0x7f,0x11,0xd9,0x5c,0x41,0x1f,0x10,0x5a,0xd8,0x0a,0xc1,0x31,0x88,0xa5,0xcd,0x7b,0xbd,0x2d,0x74,0xd0,0x12,0xb8,0xe5,0xb4,0xb0,0x89,0x69,0x97,0x4a,0x0c,0x96,0x77,0x7e,0x65,0xb9,0xf1,0x09,0xc5,0x6e,0xc6,0x84,0x18,0xf0,0x7d,0xec,0x3a,0xdc,0x4d,0x20,0x79,0xee,0x5f,0x3e,0xd7,0xcb,0x39,0x48,}var(
    fk0 =uint32(0xa3b1bac6)
    fk1 =uint32(0x56aa3350)
    fk2 =uint32(0x677d9197)
    fk3 =uint32(0xb27022dc))var ck =[32]uint32{0x00070e15,0x1c232a31,0x383f464d,0x545b6269,0x70777e85,0x8c939aa1,0xa8afb6bd,0xc4cbd2d9,0xe0e7eef5,0xfc030a11,0x181f262d,0x343b4249,0x50575e65,0x6c737a81,0x888f969d,0xa4abb2b9,0xc0c7ced5,0xdce3eaf1,0xf8ff060d,0x141b2229,0x30373e45,0x4c535a61,0x686f767d,0x848b9299,0xa0a7aeb5,0xbcc3cad1,0xd8dfe6ed,0xf4fb0209,0x10171e25,0x2c333a41,0x484f565d,0x646b7279,}funcdelta(a uint32)uint32{
    a =(uint32(sbox[byte(a>>24)])<<24)|(a &0x00ffffff)
    a =(uint32(sbox[byte(a>>16)])<<16)|(a &0xff00ffff)
    a =(uint32(sbox[byte(a>>8)])<<8)|(a &0xffff00ff)
    a =(uint32(sbox[byte(a)]))|(a &0xffffff00)return a
}funcrol32(x uint32, n int)uint32{return(x << n)|((x &0xffffffff)>>(32- n))}funcL1(a uint32)uint32{return a ^rol32(a,2)^rol32(a,10)^rol32(a,18)^rol32(a,24)}funcL2(a uint32)uint32{return a ^rol32(a,13)^rol32(a,23)}funcT1(a uint32)uint32{returnL1(delta(a))}funcT2(a uint32)uint32{returnL2(delta(a))}funcF(a, b, c, d, k uint32)uint32{return a ^T1(b^c^d^k)}

block.go

package sm4

import("encoding/binary""unsafe")// GB/T 32907-2016// http://c.gb688.cn/bzgk/gb/showGb?type=online&hcno=7803DE42D3BC5E80B0C3E5D8E873D56AfuncencryptBlockGo(xk []uint32, dst, src []byte){_= src[15]// early bounds check
    s0 := binary.BigEndian.Uint32(src[0:4])
    s1 := binary.BigEndian.Uint32(src[4:8])
    s2 := binary.BigEndian.Uint32(src[8:12])
    s3 := binary.BigEndian.Uint32(src[12:16])for i :=0; i <32; i++{

        si :=F(s0, s1, s2, s3, xk[i])

        s0 = s1
        s1 = s2
        s2 = s3
        s3 = si
    }_= dst[15]// early bounds check
    binary.BigEndian.PutUint32(dst[0:4], s3)
    binary.BigEndian.PutUint32(dst[4:8], s2)
    binary.BigEndian.PutUint32(dst[8:12], s1)
    binary.BigEndian.PutUint32(dst[12:16], s0)}funcexpandEncKeyGo(key []byte)[]uint32{_= key[15]// early bounds check
    s0 := binary.BigEndian.Uint32(key[0:4])
    s1 := binary.BigEndian.Uint32(key[4:8])
    s2 := binary.BigEndian.Uint32(key[8:12])
    s3 := binary.BigEndian.Uint32(key[12:16])

    k0 := s0 ^ fk0
    k1 := s1 ^ fk1
    k2 := s2 ^ fk2
    k3 := s3 ^ fk3

    rk :=make([]uint32,32)for i :=0; i <32; i++{
        x := k0 ^T2(k1^k2^k3^ck[i])

        k0 = k1
        k1 = k2
        k2 = k3
        k3 = x

        rk[i]= x
    }return rk
}funcexpandDecKeyGo(key []byte)[]uint32{_= key[15]// early bounds check
    s0 := binary.BigEndian.Uint32(key[0:4])
    s1 := binary.BigEndian.Uint32(key[4:8])
    s2 := binary.BigEndian.Uint32(key[8:12])
    s3 := binary.BigEndian.Uint32(key[12:16])

    k0 := s0 ^ fk0
    k1 := s1 ^ fk1
    k2 := s2 ^ fk2
    k3 := s3 ^ fk3

    rk :=make([]uint32,32)for i :=0; i <32; i++{
        x := k0 ^T2(k1^k2^k3^ck[i])

        k0 = k1
        k1 = k2
        k2 = k3
        k3 = x

        rk[31-i]= x
    }return rk
}// copy from https://github.com/golang/go/blob/15da892a4950a4caac987ee72c632436329f62d5/src/crypto/internal/subtle/aliasing.go#L30funcinexactOverlap(x, y []byte)bool{iflen(x)==0||len(y)==0||&x[0]==&y[0]{returnfalse}returnanyOverlap(x, y)}funcanyOverlap(x, y []byte)bool{returnlen(x)>0&&len(y)>0&&uintptr(unsafe.Pointer(&x[0]))<=uintptr(unsafe.Pointer(&y[len(y)-1]))&&uintptr(unsafe.Pointer(&y[0]))<=uintptr(unsafe.Pointer(&x[len(x)-1]))}

sm4.go

package sm4

import("crypto/cipher""strconv")type sm4 struct{
    enc []uint32
    dec []uint32}type KeySizeError intfunc(k KeySizeError)Error()string{return"cryptox/sm4: invalid key size "+ strconv.Itoa(int(k))}//GB/T 32907-2016; SM4-128funcNewCipher(key []byte)(cipher.Block,error){
    k :=len(key)switch k {default:returnnil,KeySizeError(k)case16:break}returnnewCipher(key)}funcnewCipher(key []byte)(cipher.Block,error){
    c := sm4{}
    c.enc =expandEncKeyGo(key)
    c.dec =expandDecKeyGo(key)return&c,nil}func(c *sm4)BlockSize()int{return BlockSize }func(c *sm4)Encrypt(dst, src []byte){iflen(src)< BlockSize {panic("crypto/sm4: input not full block")}iflen(dst)< BlockSize {panic("crypto/sm4: output not full block")}ifinexactOverlap(dst[:BlockSize], src[:BlockSize]){panic("crypto/sm4: invalid buffer overlap")}encryptBlockGo(c.enc, dst, src)}func(c *sm4)Decrypt(dst, src []byte){iflen(src)< BlockSize {panic("crypto/sm4: input not full block")}iflen(dst)< BlockSize {panic("crypto/sm4: output not full block")}ifinexactOverlap(dst[:BlockSize], src[:BlockSize]){panic("crypto/sm4: invalid buffer overlap")}encryptBlockGo(c.dec, dst, src)}

遗留问题

SM4 是128位加密算法，但是对于加密很多数据时，需要填充数据，使其长度是128位的整数倍； 常见的填充方式；

• NoPadding
• PKCS5Padding
• PKCS7Padding
• ISO10126Padding
• ISO7816-4Padding
• ZeroBytePadding
• X923Padding
• TBCPadding（Trailing-Bit-Compliment）
• PKCS1Padding

AES五种加密模式（CBC、ECB、CTR、OCF、CFB），那么SM4 也应该有该五种加密模式；

• 电码本模式（Electronic Codebook Book (ECB)）
• 密码分组链接模式（Cipher Block Chaining (CBC)）
• 计算器模式（Counter (CTR)）；
• 密码反馈模式（Cipher FeedBack (CFB)）
• 输出反馈模式（Output FeedBack (OFB)）

待续。。。。