golang 实现国密SM4



  • 0 引言

    sm4 算法是国密局公布的商用分组算法标准(国密资料: http://www.csdn.net/tag/sm2 )。该算法的分组长度为 128 比特,密钥长度为 128 比特。加密算法与密钥扩展算法都采用 32 轮非线性迭代结构。解密算法与加密算法的结构相同,只是轮密钥的使用顺序相反,解密轮密钥是加密轮密钥的逆序。本文主要介绍了用golang 语言实现sm4分组算法,用于测试学习。

    1 算法结构

    sm4密码算法是一个分组算法。该算法的分组长度为128比特,密匙长度为128比特。加密算法与密钥算法都采用了32轮非线性迭代结构。数据解密和数据加密的算法结构相同,只是轮密钥的使用顺序相反,解密轮密钥是加密轮密钥的逆序。

    2 S盒

    S 盒为固定的 8 比特输入 8 比特输出的置换,记为Sbox ⋅ 。

    var 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}
    

    2 密钥及密钥参量

    • FK = (FK0,FK1,FK2,FK3)为系统参数,CK = (CK0>,CK1,⋯,CK31)
    var fk = []uint32{0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc}
    var ck = []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}
    

    3 函数

    • 左旋运算<<<
    func rl(x uint32, n uint32) uint32 {
    	n %= 32
    	return (x<<n | x>>(32-n))
    }
    
    • 线性变换L
      C=L(B)=B ^ (B<<<2 )^ (B<<<10) ^ (B<<<18) ^ (B<<<24)
    func l0(x uint32) uint32 {
    	return x ^ rl(x, 2) ^ rl(x, 10) ^ rl(x, 18) ^ rl(x, 24)
    }
    
    • 线性变换L' C=L'(B)=B ^ (B<<<13) ^ (B<<<23)
    func l1(x uint32) uint32 {
    	return x ^ rl(x, 13) ^ rl(x, 23)
    }
    
    • 非线性变换τ(.)
    func p(a uint32) uint32 {
    	return (uint32(sbox[a>>24]) << 24) ^ (uint32(sbox[(a>>16)&0xff]) << 16) ^ (uint32(sbox[(a>>8)&0xff]) << 8) ^ uint32(sbox[(a)&0xff])
    }
    
    • 可逆变换T,由非线性变换 τ 和线性变换 L 复合而成,即 T(.)=L(τ(.))
    func t0(r uint32) uint32 {
    	return l0(p(r))
    }
    
    • 可逆变换TN,由非线性变换 τ 和线性变换 L' 复合而成,即 T(.)=L'(τ(.))
    func t1(r uint32) uint32 {
    	return l1(p(r))
    }
    

    4 算法描述

    加密算法由32次迭代运算和1次反序变换组成;解密变换与加密变换结构相同,不同的仅是轮密钥的使用顺序。解密时,使用轮密钥序 rk42 , rk40, ⋯ , rk0

    func cryptBlock(subkeys, dst, src []byte, decrypt bool) {
    	var (
    		k0, k1, k2, k3 uint32
    		d0, d1, d2, d3 uint32
    		y0, y1, y2, y3 uint32
    		rk             = make([]uint32, 32)
    	)
    	k0 = getu32(subkeys, 0)
    	k1 = getu32(subkeys, 4)
    	k2 = getu32(subkeys, 8)
    	k3 = getu32(subkeys, 12)
    	d0 = getu32(src, 0)
    	d1 = getu32(src, 4)
    	d2 = getu32(src, 8)
    	d3 = getu32(src, 12)
    	k0 = k0 ^ fk[0]
    	k1 = k1 ^ fk[1]
    	k2 = k2 ^ fk[2]
    	k3 = k3 ^ fk[3]
    	for i := 0; i < 32; i++ {
    		rk[i] = f1(k0, k1, k2, k3, ck[i])
    		k0 = k1
    		k1 = k2
    		k2 = k3
    		k3 = rk[i]
    		if !decrypt {
    			t := f0(d0, d1, d2, d3, rk[i])
    			d0 = d1
    			d1 = d2
    			d2 = d3
    			d3 = t
    		}
    	}
    	if decrypt {
    		for i := 0; i < 32; i++ {
    			t := f0(d0, d1, d2, d3, rk[31-i])
    			d0 = d1
    			d1 = d2
    			d2 = d3
    			d3 = t
    		}
    	}
    	y0 = d3
    	y1 = d2
    	y2 = d1
    	y3 = d0
    	putu32(dst, y0, 0)
    	putu32(dst, y1, 4)
    	putu32(dst, y2, 8)
    	putu32(dst, y3, 12)
    }
    
    func getu32(b []byte, i uint32) uint32 {
    	return (uint32(b[i]) << 24) | (uint32(b[i+1]) << 16) | (uint32(b[i+2]) << 8) | uint32(b[i+3])
    }
    
    func putu32(b []byte, n, i uint32) {
    	b[i] = byte(n >> 24)
    	b[i+1] = byte(n >> 16)
    	b[i+2] = byte(n >> 8)
    	b[i+3] = byte(n)
    }
    

    5 测试

    func Test_cryptBlock(t *testing.T) {
    	data := []byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef, 0xfe, 0xdc, 0xba, 0x98, 0x76, 0x54, 0x32, 0x10}
    	fmt.Printf("da : %x \n", data)
    	key := []byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef, 0xfe, 0xdc, 0xba, 0x98, 0x76, 0x54, 0x32, 0x10}
    	var en, de []byte = make([]byte, 16), make([]byte, 16)
    	cryptBlock(key, en, data, false)
    	fmt.Printf("en : %x \n", en)
    	cryptBlock(key, de, en, true)
    	fmt.Printf("de : %x \n", de)
    }
    // 运行结果
    //=== RUN   Test_cryptBlock
    //da : 0123456789abcdeffedcba9876543210 
    //en : 681edf34d206965e86b3e94f536e4246 
    //de : 0123456789abcdeffedcba9876543210 
    //-- PASS: Test_cryptBlock (0.00s)
    //PASS
    


  • 缺少f0、f1函数,请问这两个函数该如何实现呢


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