sm4 算法实现

忘是亡心i 2021-12-13 22:27 255阅读 0赞

最近在研究国密算法，主要分为：SM2、SM3、SM4。其中SM2为非对称加密算法，SM3为哈希摘要算法，SM4为对称加密算法。

1.在SM4算法源文件中主要有以下几个函数：

void sm4_setkey_enc( sm4_context *ctx, unsigned char key[16] );
    void sm4_setkey_dec( sm4_context *ctx, unsigned char key[16] );
    void sm4_crypt_ecb( sm4_context *ctx, int mode,int length, unsigned char *input,
                        unsigned char *output);
    void sm4_crypt_cbc( sm4_context *ctx, int mode, int length,
                         unsigned char iv[16], unsigned char *input,
                         unsigned char *output );

2.还有一个重要的结构体：

/**
     * \brief          SM4 context structure
     */
    typedef struct
    {
        int mode;                   /*!<  encrypt/decrypt   */
        unsigned long sk[32];       /*!<  SM4 subkeys       */
    }
    sm4_context;

结构体中的mode参数控制加密还是解密，其中mode=1为加密，mode=0为解密。数组sk为轮密钥。SM4为32轮加密变换。

3.加密函数：

/**
     * \brief          SM4 key schedule (128-bit, encryption)
     *
     * \param ctx      SM4 context to be initialized
     * \param key      16-byte secret key
     */
    void sm4_setkey_enc(sm4_context *ctx，unsigned char key[16])；

这个函数是用来加密明文的，一个参数分别为sm4\_context \*ctx和一个key。

其内部会调用static void sm4\_setkey( unsigned long SK\[32\], unsigned char key\[16\] )函数

这个函数是用来设置密钥的，这个函数内部会对当前传入的主密钥进行32轮的迭代，每次迭代的轮密钥都被存放到ctx结构中的sk数组中。

4.解密函数：

/**
     * \brief          SM4 key schedule (128-bit, decryption)
     *
     * \param ctx      SM4 context to be initialized
     * \param key      16-byte secret key
     */
    void sm4_setkey_dec( sm4_context *ctx, unsigned char key[16] );

这个函数为解密函数，是进行密文解密的。参数与加密函数一样。

5.ECB工作模式：

/**
     * \brief          SM4-ECB block encryption/decryption
     * \param ctx      SM4 context
     * \param mode     SM4_ENCRYPT or SM4_DECRYPT
     * \param length   length of the input data
     * \param input    input block
     * \param output   output block
     */
    void sm4_crypt_ecb( sm4_context *ctx, int mode, int length,
                         unsigned char *input,
                         unsigned char *output);

这个函数的作用是使用ECB模式（ECB（Electronic Codebook，电码本），ECB模式是分组密码的一种最基本的工作模式。根据length的长度来进行循环，每次循环都调用sm4\_one\_round进行加密或者解密，到底是加密还是解密，主要是根据第二个参数Mode来进行决定。

6. CBC工作模式：

/**
     * \brief          SM4-CBC buffer encryption/decryption
     * \param ctx      SM4 context
     * \param mode     SM4_ENCRYPT or SM4_DECRYPT
     * \param length   length of the input data
     * \param iv       initialization vector (updated after use)
     * \param input    buffer holding the input data
     * \param output   buffer holding the output data
     */
    void sm4_crypt_cbc( sm4_context *ctx, int mode, int length,
                         unsigned char iv[16],
                         unsigned char *input,
                         unsigned char *output );

以上就是SM4加密算法的函数简介，具体的代码实现可不用掌握，下面是完整代码：

7.sm4.h头文件

/**
     * \file sm4.h
     */
    #ifndef XYSSL_SM4_H
    #define XYSSL_SM4_H
     
    #define SM4_ENCRYPT     1
    #define SM4_DECRYPT     0
     
    /**
     * \brief          SM4 context structure
     */
    typedef struct
    {
        int mode;                   /*!<  encrypt/decrypt   */
        unsigned long sk[32];       /*!<  SM4 subkeys       */
    }
    sm4_context;
     
     
    #ifdef __cplusplus
    extern "C" {
    #endif
     
    /**
     * \brief          SM4 key schedule (128-bit, encryption)
     *
     * \param ctx      SM4 context to be initialized
     * \param key      16-byte secret key
     */
    void sm4_setkey_enc( sm4_context *ctx, unsigned char key[16] );
     
    /**
     * \brief          SM4 key schedule (128-bit, decryption)
     *
     * \param ctx      SM4 context to be initialized
     * \param key      16-byte secret key
     */
    void sm4_setkey_dec( sm4_context *ctx, unsigned char key[16] );
     
    /**
     * \brief          SM4-ECB block encryption/decryption
     * \param ctx      SM4 context
     * \param mode     SM4_ENCRYPT or SM4_DECRYPT
     * \param length   length of the input data
     * \param input    input block
     * \param output   output block
     */
    void sm4_crypt_ecb( sm4_context *ctx,
                         int mode,
                         int length,
                         unsigned char *input,
                         unsigned char *output);
     
    /**
     * \brief          SM4-CBC buffer encryption/decryption
     * \param ctx      SM4 context
     * \param mode     SM4_ENCRYPT or SM4_DECRYPT
     * \param length   length of the input data
     * \param iv       initialization vector (updated after use)
     * \param input    buffer holding the input data
     * \param output   buffer holding the output data
     */
    void sm4_crypt_cbc( sm4_context *ctx,
                         int mode,
                         int length,
                         unsigned char iv[16],
                         unsigned char *input,
                         unsigned char *output );
     
    #ifdef __cplusplus
    }
    #endif
     
    #endif /* sm4.h */

8.sm4.c源文件

/*
     * SM4 Encryption alogrithm (SMS4 algorithm)
     * GM/T 0002-2012 Chinese National Standard ref:http://www.oscca.gov.cn/ 
     * thanks to Xyssl
     * thnaks and refers to http://hi.baidu.com/numax/blog/item/80addfefddfb93e4cf1b3e61.html
     * author:goldboar
     * email:goldboar@163.com
     * 2012-4-20
     */
     
    // Test vector 1
    // plain: 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10
    // key:   01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10
    //        round key and temp computing result:
    //        rk[ 0] = f12186f9 X[ 0] = 27fad345
    //            rk[ 1] = 41662b61 X[ 1] = a18b4cb2
    //            rk[ 2] = 5a6ab19a X[ 2] = 11c1e22a
    //            rk[ 3] = 7ba92077 X[ 3] = cc13e2ee
    //            rk[ 4] = 367360f4 X[ 4] = f87c5bd5
    //            rk[ 5] = 776a0c61 X[ 5] = 33220757
    //            rk[ 6] = b6bb89b3 X[ 6] = 77f4c297
    //            rk[ 7] = 24763151 X[ 7] = 7a96f2eb
    //            rk[ 8] = a520307c X[ 8] = 27dac07f
    //            rk[ 9] = b7584dbd X[ 9] = 42dd0f19
    //            rk[10] = c30753ed X[10] = b8a5da02
    //            rk[11] = 7ee55b57 X[11] = 907127fa
    //            rk[12] = 6988608c X[12] = 8b952b83
    //            rk[13] = 30d895b7 X[13] = d42b7c59
    //            rk[14] = 44ba14af X[14] = 2ffc5831
    //            rk[15] = 104495a1 X[15] = f69e6888
    //            rk[16] = d120b428 X[16] = af2432c4
    //            rk[17] = 73b55fa3 X[17] = ed1ec85e
    //            rk[18] = cc874966 X[18] = 55a3ba22
    //            rk[19] = 92244439 X[19] = 124b18aa
    //            rk[20] = e89e641f X[20] = 6ae7725f
    //            rk[21] = 98ca015a X[21] = f4cba1f9
    //            rk[22] = c7159060 X[22] = 1dcdfa10
    //            rk[23] = 99e1fd2e X[23] = 2ff60603
    //            rk[24] = b79bd80c X[24] = eff24fdc
    //            rk[25] = 1d2115b0 X[25] = 6fe46b75
    //            rk[26] = 0e228aeb X[26] = 893450ad
    //            rk[27] = f1780c81 X[27] = 7b938f4c
    //            rk[28] = 428d3654 X[28] = 536e4246
    //            rk[29] = 62293496 X[29] = 86b3e94f
    //            rk[30] = 01cf72e5 X[30] = d206965e
    //            rk[31] = 9124a012 X[31] = 681edf34
    // cypher: 68 1e df 34 d2 06 96 5e 86 b3 e9 4f 53 6e 42 46
    //         
    // test vector 2
    // the same key and plain 1000000 times coumpting 
    // plain:  01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10
    // key:    01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10
    // cypher: 59 52 98 c7 c6 fd 27 1f 04 02 f8 04 c3 3d 3f 66
     
    #include "sm4.h"
    #include <string.h>
    #include <stdio.h>
     
    /*
     * 32-bit integer manipulation macros (big endian)
     */
    #ifndef GET_ULONG_BE
    #define GET_ULONG_BE(n,b,i)                             \
    {                                                       \
        (n) = ( (unsigned long) (b)[(i)    ] << 24 )        \
            | ( (unsigned long) (b)[(i) + 1] << 16 )        \
            | ( (unsigned long) (b)[(i) + 2] <<  8 )        \
            | ( (unsigned long) (b)[(i) + 3]       );       \
    }
    #endif
     
    #ifndef PUT_ULONG_BE
    #define PUT_ULONG_BE(n,b,i)                             \
    {                                                       \
        (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
        (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
        (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
        (b)[(i) + 3] = (unsigned char) ( (n)       );       \
    }
    #endif
     
    /*
     *rotate shift left marco definition
     *
     */
    #define  SHL(x,n) (((x) & 0xFFFFFFFF) << n)
    #define ROTL(x,n) (SHL((x),n) | ((x) >> (32 - n)))
     
    #define SWAP(a,b) { unsigned long t = a; a = b; b = t; t = 0; }
     
    /*
     * Expanded SM4 S-boxes
     /* Sbox table: 8bits input convert to 8 bits output*/
     
    static const unsigned char SboxTable[16][16] = 
    {
    {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}
    };
     
    /* System parameter */
    static const unsigned long FK[4] = {0xa3b1bac6,0x56aa3350,0x677d9197,0xb27022dc};
     
    /* fixed parameter */
    static const unsigned long CK[32] =
    {
    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
    };
     
     
    /*
     * private function:
     * look up in SboxTable and get the related value.
     * args:    [in] inch: 0x00~0xFF (8 bits unsigned value).
     */
    static unsigned char sm4Sbox(unsigned char inch)
    {
        unsigned char *pTable = (unsigned char *)SboxTable;
        unsigned char retVal = (unsigned char)(pTable[inch]);
        return retVal;
    }
     
    /*
     * private F(Lt) function:
     * "T algorithm" == "L algorithm" + "t algorithm".
     * args:    [in] a: a is a 32 bits unsigned value;
     * return: c: c is calculated with line algorithm "L" and nonline algorithm "t"
     */
    static unsigned long sm4Lt(unsigned long ka)
    {
        unsigned long bb = 0;
        unsigned long c = 0;
        unsigned char a[4];
        unsigned char b[4];
        PUT_ULONG_BE(ka,a,0)
        b[0] = sm4Sbox(a[0]);
        b[1] = sm4Sbox(a[1]);
        b[2] = sm4Sbox(a[2]);
        b[3] = sm4Sbox(a[3]);
        GET_ULONG_BE(bb,b,0)
        c =bb^(ROTL(bb, 2))^(ROTL(bb, 10))^(ROTL(bb, 18))^(ROTL(bb, 24));
        return c;
    }
     
    /*
     * private F function:
     * Calculating and getting encryption/decryption contents.
     * args:    [in] x0: original contents;
     * args:    [in] x1: original contents;
     * args:    [in] x2: original contents;
     * args:    [in] x3: original contents;
     * args:    [in] rk: encryption/decryption key;
     * return the contents of encryption/decryption contents.
     */
    static unsigned long sm4F(unsigned long x0, unsigned long x1, unsigned long x2, unsigned long x3, unsigned long rk)
    {
        return (x0^sm4Lt(x1^x2^x3^rk));
    }
     
     
    /* private function:
     * Calculating round encryption key.
     * args:    [in] a: a is a 32 bits unsigned value;
     * return: sk[i]: i{0,1,2,3,...31}.
     */
    static unsigned long sm4CalciRK(unsigned long ka)
    {
        unsigned long bb = 0;
        unsigned long rk = 0;
        unsigned char a[4];
        unsigned char b[4];
        PUT_ULONG_BE(ka,a,0)
        b[0] = sm4Sbox(a[0]);
        b[1] = sm4Sbox(a[1]);
        b[2] = sm4Sbox(a[2]);
        b[3] = sm4Sbox(a[3]);
        GET_ULONG_BE(bb,b,0)
        rk = bb^(ROTL(bb, 13))^(ROTL(bb, 23));
        return rk;
    }
     
    static void sm4_setkey( unsigned long SK[32], unsigned char key[16] )
    {
        unsigned long MK[4];
        unsigned long k[36];
        unsigned long i = 0;
     
        GET_ULONG_BE( MK[0], key, 0 );
        GET_ULONG_BE( MK[1], key, 4 );
        GET_ULONG_BE( MK[2], key, 8 );
        GET_ULONG_BE( MK[3], key, 12 );
        k[0] = MK[0]^FK[0];
        k[1] = MK[1]^FK[1];
        k[2] = MK[2]^FK[2];
        k[3] = MK[3]^FK[3];
        for(; i<32; i++)
        {
            k[i+4] = k[i] ^ (sm4CalciRK(k[i+1]^k[i+2]^k[i+3]^CK[i]));
            SK[i] = k[i+4];
        }
     
    }
     
    /*
     * SM4 standard one round processing
     *
     */
    static void sm4_one_round( unsigned long sk[32],
                        unsigned char input[16],
                        unsigned char output[16] )
    {
        unsigned long i = 0;
        unsigned long ulbuf[36];
     
        memset(ulbuf, 0, sizeof(ulbuf));
        GET_ULONG_BE( ulbuf[0], input, 0 )
        GET_ULONG_BE( ulbuf[1], input, 4 )
        GET_ULONG_BE( ulbuf[2], input, 8 )
        GET_ULONG_BE( ulbuf[3], input, 12 )
        while(i<32)
        {
            ulbuf[i+4] = sm4F(ulbuf[i], ulbuf[i+1], ulbuf[i+2], ulbuf[i+3], sk[i]);
    // #ifdef _DEBUG
    //            printf("rk(%02d) = 0x%08x,  X(%02d) = 0x%08x \n",i,sk[i], i, ulbuf[i+4] );
    // #endif
            i++;
        }
        PUT_ULONG_BE(ulbuf[35],output,0);
        PUT_ULONG_BE(ulbuf[34],output,4);
        PUT_ULONG_BE(ulbuf[33],output,8);
        PUT_ULONG_BE(ulbuf[32],output,12);
    }
     
    /*
     * SM4 key schedule (128-bit, encryption)
     */
    void sm4_setkey_enc( sm4_context *ctx, unsigned char key[16] )
    {
        ctx->mode = SM4_ENCRYPT;
        sm4_setkey( ctx->sk, key );
    }
     
    /*
     * SM4 key schedule (128-bit, decryption)
     */
    void sm4_setkey_dec( sm4_context *ctx, unsigned char key[16] )
    {
        int i;
        ctx->mode = SM4_ENCRYPT;
        sm4_setkey( ctx->sk, key );
        for( i = 0; i < 16; i ++ )
        {
            SWAP( ctx->sk[ i ], ctx->sk[ 31-i] );
        }
    }
     
     
    /*
     * SM4-ECB block encryption/decryption
     */
     
    void sm4_crypt_ecb( sm4_context *ctx,
                       int mode,
                       int length,
                       unsigned char *input,
                       unsigned char *output)
    {
        while( length > 0 )
        {
            sm4_one_round( ctx->sk, input, output );
            input  += 16;
            output += 16;
            length -= 16;
        }
     
    }
     
    /*
     * SM4-CBC buffer encryption/decryption
     */
    void sm4_crypt_cbc( sm4_context *ctx,
                        int mode,
                        int length,
                        unsigned char iv[16],
                        unsigned char *input,
                        unsigned char *output )
    {
        int i;
        unsigned char temp[16];
     
        if( mode == SM4_ENCRYPT )
        {
            while( length > 0 )
            {
                for( i = 0; i < 16; i++ )
                    output[i] = (unsigned char)( input[i] ^ iv[i] );
     
                sm4_one_round( ctx->sk, output, output );
                memcpy( iv, output, 16 );
     
                input  += 16;
                output += 16;
                length -= 16;
            }
        }
        else /* SM4_DECRYPT */
        {
            while( length > 0 )
            {
                memcpy( temp, input, 16 );
                sm4_one_round( ctx->sk, input, output );
     
                for( i = 0; i < 16; i++ )
                    output[i] = (unsigned char)( output[i] ^ iv[i] );
     
                memcpy( iv, temp, 16 );
     
                input  += 16;
                output += 16;
                length -= 16;
            }
        }
    }

9.测试文件

/*
     * SM4/SMS4 algorithm test programme
     * 2012-4-21
     */
     
    #include <string.h>
    #include <stdio.h>
    #include "sm4.h"
     
    int main()
    {
        unsigned char key[16] = {0x01,0x23,0x45,0x67,0x89,0xab,0xcd,0xef,0xfe,0xdc,0xba,0x98,0x76,0x54,0x32,0x10};
        unsigned char input[16] = {0x01,0x23,0x45,0x67,0x89,0xab,0xcd,0xef,0xfe,0xdc,0xba,0x98,0x76,0x54,0x32,0x10};
        unsigned char output[16];
        sm4_context ctx;
        unsigned long i;
     
        //encrypt standard testing vector
        sm4_setkey_enc(&ctx,key);
        sm4_crypt_ecb(&ctx,1,16,input,output);
        for(i=0;i<16;i++)
            printf("%02x ", output[i]);
        printf("\n");
     
        //decrypt testing
        sm4_setkey_dec(&ctx,key);
        sm4_crypt_ecb(&ctx,0,16,output,output);
        for(i=0;i<16;i++)
            printf("%02x ", output[i]);
        printf("\n");
     
        //encrypt 1M times testing vector based on standards.
        i = 0;
        sm4_setkey_enc(&ctx,key);
        while (i<1000000) 
        {
            sm4_crypt_ecb(&ctx,1,16,input,input);
            i++;
        }
        for(i=0;i<16;i++)
            printf("%02x ", input[i]);
        printf("\n");
        
        return 0;
    }