DES加解密算法（C语言实现）

DES加密和解密算法的实现（C语言）

主要是做个记录，害怕以后代码丢了，先放到这里了。

DES再不进行介绍了，可以看上一篇的 DES 的python实现

转载请注明出处：https://www.cnblogs.com/wangyanzhong123/p/13784272.html

说明

这个版本用了很多位运算，也没有添加注释，所以可能阅读起来会有一些困难。其中实现的是 DES 的 CBC 模式下的加解密，可以保证的是结果一定是正确的。

源代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <time.h>

const uint8_t IP[] = {
    58, 50, 42, 34, 26, 18, 10,  2, 60, 52, 44, 36, 28, 20, 12,  4,
    62, 54, 46, 38, 30, 22, 14,  6, 64, 56, 48, 40, 32, 24, 16,  8,
    57, 49, 41, 33, 25, 17,  9,  1, 59, 51, 43, 35, 27, 19, 11,  3,
    61, 53, 45, 37, 29, 21, 13,  5, 63, 55, 47, 39, 31, 23, 15,  7
};

const uint8_t invIP[] = {
    40,  8, 48, 16, 56, 24, 64, 32, 39,  7, 47, 15, 55, 23, 63, 31,
    38,  6, 46, 14, 54, 22, 62, 30, 37,  5, 45, 13, 53, 21, 61, 29,
    36,  4, 44, 12, 52, 20, 60, 28, 35,  3, 43, 11, 51, 19, 59, 27,
    34,  2, 42, 10, 50, 18, 58, 26, 33,  1, 41,  9, 49, 17, 57, 25
};

const uint8_t E[] = {
    32,  1,  2,  3,  4,  5,  4,  5,  6,  7,  8,  9,
     8,  9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17,
    16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25,
    24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32,  1
};

const uint8_t P[] = {
    16,  7, 20, 21, 29, 12, 28, 17,
     1, 15, 23, 26, 5, 18, 31, 10,
     2,  8, 24, 14, 32, 27,  3,  9,
    19, 13, 30,  6, 22, 11,  4, 25
};

const uint8_t S[8][64] = {{
    /* S1 */
    14,  4, 13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7,
     0, 15,  7,  4, 14,  2, 13,  1, 10,  6, 12, 11,  9,  5,  3,  8,
     4,  1, 14,  8, 13,  6,  2, 11, 15, 12,  9,  7,  3, 10,  5,  0,
    15, 12,  8,  2,  4,  9,  1,  7,  5, 11,  3, 14, 10,  0,  6, 13
},{
    /* S2 */
    15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10,
     3, 13,  4,  7, 15,  2,  8, 14, 12,  0,  1, 10,  6,  9, 11,  5,
     0, 14,  7, 11, 10,  4, 13,  1,  5,  8, 12,  6,  9,  3,  2, 15,
    13,  8, 10,  1,  3, 15,  4,  2, 11,  6,  7, 12,  0,  5, 14,  9
},{
    /* S3 */
    10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8,
    13,  7,  0,  9,  3,  4,  6, 10,  2,  8,  5, 14, 12, 11, 15,  1,
    13,  6,  4,  9,  8, 15,  3,  0, 11,  1,  2, 12,  5, 10, 14,  7,
     1, 10, 13,  0,  6,  9,  8,  7,  4, 15, 14,  3, 11,  5,  2, 12
},{
    /* S4 */
     7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15,
    13,  8, 11,  5,  6, 15,  0,  3,  4,  7,  2, 12,  1, 10, 14,  9,
    10,  6,  9,  0, 12, 11,  7, 13, 15,  1,  3, 14,  5,  2,  8,  4,
     3, 15,  0,  6, 10,  1, 13,  8,  9,  4,  5, 11, 12,  7,  2, 14
},{
    /* S5 */
     2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9,
    14, 11,  2, 12,  4,  7, 13,  1,  5,  0, 15, 10,  3,  9,  8,  6,
     4,  2,  1, 11, 10, 13,  7,  8, 15,  9, 12,  5,  6,  3,  0, 14,
    11,  8, 12,  7,  1, 14,  2, 13,  6, 15,  0,  9, 10,  4,  5,  3
},{
    /* S6 */
    12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11,
    10, 15,  4,  2,  7, 12,  9,  5,  6,  1, 13, 14,  0, 11,  3,  8,
     9, 14, 15,  5,  2,  8, 12,  3,  7,  0,  4, 10,  1, 13, 11,  6,
     4,  3,  2, 12,  9,  5, 15, 10, 11, 14,  1,  7,  6,  0,  8, 13
},{
    /* S7 */
     4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1,
    13,  0, 11,  7,  4,  9,  1, 10, 14,  3,  5, 12,  2, 15,  8,  6,
     1,  4, 11, 13, 12,  3,  7, 14, 10, 15,  6,  8,  0,  5,  9,  2,
     6, 11, 13,  8,  1,  4, 10,  7,  9,  5,  0, 15, 14,  2,  3, 12
},{
    /* S8 */
    13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7,
     1, 15, 13,  8, 10,  3,  7,  4, 12,  5,  6, 11,  0, 14,  9,  2,
     7, 11,  4,  1,  9, 12, 14,  2,  0,  6, 10, 13, 15,  3,  5,  8,
     2,  1, 14,  7,  4, 10,  8, 13, 15, 12,  9,  0,  3,  5,  6, 11
}};

const uint8_t PC1[] = {
    57, 49, 41, 33, 25, 17,  9,  1, 58, 50, 42, 34, 26, 18,
    10,  2, 59, 51, 43, 35, 27, 19, 11,  3, 60, 52, 44, 36,
    63, 55, 47, 39, 31, 23, 15,  7, 62, 54, 46, 38, 30, 22,
    14,  6, 61, 53, 45, 37, 29, 21, 13,  5, 28, 20, 12,  4
};

const uint8_t PC2[] = {
    14, 17, 11, 24,  1,  5,  3, 28, 15,  6, 21, 10,
    23, 19, 12,  4, 26,  8, 16,  7, 27, 20, 13,  2,
    41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48,
    44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32
};

const uint8_t shift_steps[] = {
    1,  1,  2,  2,  2,  2,  2,  2,  1,  2,  2,  2,  2,  2,  2,  1
};

uint64_t pc1(uint64_t key){
    uint64_t result = 0;
    for (int i = 0; i < 56; i ++){
        result = result << 1;
        result = result | ((key >> (64-PC1[i])) & 0x0000000000000001);
    }
    return (result & 0x00ffffffffffffff);
}

uint64_t pc2(uint64_t key){
    uint64_t result = 0;
    for (int i = 0; i < 48; i ++){
        result = result << 1;
        result = result | (uint64_t)((key >> (56-PC2[i])) & 0x0000000000000001);
    }
    return (result & 0x0000ffffffffffff);
}

uint64_t ip(uint64_t input){
    uint64_t result = 0;
    for (int i = 0; i < 64; i ++){
        result = result << 1;
        result = result | ((input >> (64-IP[i])) & 0x0000000000000001);
    }
    return result;
}

uint64_t inv_ip(uint64_t input){
    uint64_t result = 0;
    for (int i = 0; i < 64; i ++){
        result = result << 1;
        result = result | ((input >> (64-invIP[i])) & 0x0000000000000001);
    }
    return result;
}

uint64_t extend(uint32_t input){
    uint64_t result = 0;
    for (int i = 0; i < 48; i ++){
        result = result << 1;
        result = result | (uint64_t)((input >> (32-E[i])) & 0x00000001);
    }
    return (result & 0x0000ffffffffffff);
}

// uint32_t s(uint64_t input){
//     uint32_t result = 0;
//     uint8_t *blocks = (uint8_t*)malloc(sizeof(uint8_t)*8);
//     uint8_t row, column;
//     for (int i = 0; i < 8; i ++){
//         blocks[i] = (uint8_t)((input >> (42 - 6*i)) & 0x000000000000003f);
//         row = ((blocks[i] >> 4) & 0x02) | (blocks[i] & 0x01);
//         column = (blocks[i] >> 1) & 0x0f;
//         result = result << 4;
//         result = result | (uint32_t)(S[i][row*16+column] & 0x0f);
//     }
//     free(blocks);
//     return result;
// }

uint32_t s(uint64_t input) {
    uint32_t res = 0;
    int row = 0;
    int col = 0;
    for (int i = 0; i < 8; i++) {
        row = (uint8_t) ((input & (0x0000840000000000 >> 6*i)) >> (42-6*i));
        row = (row >> 4) | (row & 0x01);
        col = (uint8_t) ((input & (0x0000780000000000 >> 6*i)) >> (43-6*i));
        res <<= 4;
        res |= (uint32_t) (S[i][16*row+col] & 0x0f);
    }
    return res;
}

uint32_t p(uint32_t input){
    uint32_t result = 0;
    for (int i = 0; i < 32; i ++){
        result = result << 1;
        result = result | ((input >> (32-P[i])) & 0x00000001);
    }
    return result;
}

void to_uint64(uint8_t *buffer, size_t buffersize, uint64_t *result){
    uint32_t tmp1 = 0, tmp2 = 0;
    for (int i = 0; i < (buffersize/8); i ++){
        tmp1 = (((uint32_t)buffer[8*i] << 24) & 0xff000000) | (((uint32_t)buffer[8*i+1] << 16) & 0x00ff0000) |
                (((uint32_t)buffer[8*i+2] << 8) & 0x0000ff00) | (((uint32_t)buffer[8*i+3]) & 0x000000ff);
        tmp2 = (((uint32_t)buffer[8*i+4] << 24) & 0xff000000) | (((uint32_t)buffer[8*i+5] << 16) & 0x00ff0000) |
                (((uint32_t)buffer[8*i+6] << 8) & 0x0000ff00) | (((uint32_t)buffer[8*i+7]) & 0x000000ff);
        result[i] = (((uint64_t)tmp1 << 32) & 0xffffffff00000000) | ((uint64_t)tmp2 & 0x00000000ffffffff);
    }
}

void to_uint8(uint64_t *buffer, size_t buffersize, uint8_t *result){
    for (int i = 0; i < buffersize; i ++){
        for (int j = 0; j < 8; j ++){
            result[8*i+j] = (uint8_t)(buffer[i] >> (56-8*j));
        }
    }
}

uint64_t hex_2_uint64(char *string){
    uint64_t result = 0;
    size_t len = 0;
    len = strlen(string);
    for (int i = 0; i < len; i ++){
        if (string[15-i] >= '0' && string[15-i] <= '9') {
            result += (uint64_t)(string[15-i]-'0') * ((uint64_t)(1) << (4*i));
        } else if (string[15-i] >= 'a' && string[15-i] <= 'f') {
            result += (uint64_t)(string[15-i]-'a' + 10) * ((uint64_t)(1) << (4*i));
        } else if (string[15-i] >= 'A' && string[15-i] <= 'F') {
            result += (uint64_t)(string[15-i]-'A' + 10) * ((uint64_t)(1) << (4*i));
        }
    }
    return result;
}

void generateSubkeys(uint64_t key, uint64_t* subkeys){
    uint32_t left, right;
    uint64_t roundkey = 0;
    uint64_t key_tmp = 0;
    key_tmp = pc1(key);
    left = (uint32_t)((key_tmp >> 28) & 0x000000000fffffff);
    right = (uint32_t)(key_tmp & 0x000000000fffffff);
    for (int i = 0; i < 16; i ++){
        int shift = shift_steps[i];
        left = (0x0fffffff & (left << shift)) | (left >> (28-shift));
        right = (0x0fffffff & (right << shift)) | (right >> (28-shift));
        roundkey = ((uint64_t)left << 28) | (uint64_t)right;
        roundkey = pc2(roundkey);
        subkeys[i] = roundkey;
    }
}

uint64_t raw_des(uint64_t text, uint64_t key, uint8_t mode){
    uint64_t* subkeys = (uint64_t*)malloc(sizeof(uint64_t)*16);
    generateSubkeys(key, subkeys);
    uint32_t L = 0, R = 0, SR = 0, PR = 0, tmp = 0;
    uint64_t ER = 0, output = 0, subkey = 0;
    text = ip(text);
    L = (text >> 32) & 0x00000000ffffffff;
    R = text & 0x00000000ffffffff;
    for (int i = 0; i < 16; i ++){
        ER = extend(R);
        subkey = (mode == 0) ? subkeys[i] : subkeys[15-i];
        ER = ER ^ subkey;
        SR = s(ER);
        PR = p(SR);
        tmp = R;
        R = L ^ PR;
        L = tmp;
    }
    free(subkeys);
    output = inv_ip(((uint64_t)(R) << 32 ) | (uint64_t)(L));
    return output;
}

uint64_t des_ede2(uint64_t text, uint64_t key1, uint64_t key2, uint8_t mode){
    uint64_t result;
    result = (mode == 0) ? raw_des(text, key1, 0) : raw_des(text, key1, 1);
    result = (mode == 0) ? raw_des(result, key2, 1) : raw_des(result, key2, 0);
    result = (mode == 0) ? raw_des(result, key1, 0) : raw_des(result, key1, 1);
    return result;
}

void des_cbc_enc(FILE* in, FILE* out, uint64_t key, uint64_t iv){
    uint8_t *filebuffer;
    size_t filesize = 0, padding_size = 0;
    uint64_t *blocks, *output;
    clock_t start, end;
    fseek(in, 0, SEEK_END);
    filesize = ftell(in);
    rewind(in);
    padding_size = 8 - filesize % 8;
    filebuffer = (uint8_t*)malloc(sizeof(uint8_t)*(filesize + padding_size));
    blocks = (uint64_t*)malloc(sizeof(uint64_t)*((filesize + padding_size)/8));
    output = (uint64_t*)malloc(sizeof(uint64_t)*((filesize + padding_size)/8));
    fread(filebuffer, sizeof(uint8_t), filesize, in);
    memset(filebuffer+filesize, (uint8_t)padding_size, padding_size);
    to_uint64(filebuffer, (filesize+padding_size), blocks);
    start = clock();
    for (int i = 0; i < (filesize+padding_size)/8; i ++){
        output[i] = raw_des((blocks[i] ^ iv), key, 0);
        iv = output[i];
    }
    end = clock();
    fwrite(output, sizeof(uint64_t), ((filesize + padding_size)/8), out);
    printf("time cost: %f s\n", (double)(end-start)/CLOCKS_PER_SEC);
    free(filebuffer);
    free(blocks);
    free(output);
}

void des_cbc_dec(FILE* in, FILE* out, uint64_t key, uint64_t iv){
    uint64_t *filebuffer;
    uint64_t *outbuffer;
    uint8_t *out8_tbuffer;
    size_t filesize = 0, padding_size = 0;
    clock_t start, end;
    fseek(in, 0, SEEK_END);
    filesize = ftell(in);
    rewind(in);
    filebuffer = (uint64_t*)malloc(sizeof(uint64_t)*(filesize/8));
    outbuffer = (uint64_t*)malloc(sizeof(uint64_t)*(filesize/8));
    out8_tbuffer = (uint8_t*)malloc(sizeof(uint8_t)*filesize);
    fread(filebuffer, sizeof(uint64_t), filesize/8, in);
    start = clock();
    for (int i = 0 ; i < (filesize/8); i ++){
        outbuffer[i] = raw_des(filebuffer[i], key, 1) ^ iv;
        iv = filebuffer[i];
    }
    end = clock();
    to_uint8(outbuffer, filesize/8, out8_tbuffer);
    padding_size = (size_t)out8_tbuffer[filesize-1];
    fwrite(out8_tbuffer, sizeof(uint8_t), filesize-padding_size, out);
    printf("time cost: %f s\n", (double)(end-start)/CLOCKS_PER_SEC);
    free(filebuffer);
    free(outbuffer);
    free(out8_tbuffer);
}

int main(int argc, char **argv){
    char *inputfile = "-f";
    char *inputstring = "-s";
    char *mod = "-enc";
    if (argc < 2){
        printf("usage: %s 'string'\n", argv[0]);
        return 1;
    } else {
        if (!strcmp(argv[1], inputfile)){
            FILE *in, *out;
            in = fopen(argv[3], "rb");
            if (in == NULL) {
                printf("%s not exist\n",argv[3]);
                return -1;
            } else {
                out = fopen(argv[4], "wb+");
                (!strcmp(argv[2],mod))? des_cbc_enc(in, out, hex_2_uint64(argv[5]), hex_2_uint64(argv[6]))
                                      : des_cbc_dec(in, out, hex_2_uint64(argv[5]), hex_2_uint64(argv[6]));
                fclose(in);
                fclose(out);
            }
        } else if (!strcmp(argv[1], inputstring)) {
            uint64_t cipher = 0;
            clock_t start, end;
            double duration;
            start = clock();
            for (int i = 0; i < 1000; i ++)
                if(!strcmp(argv[2],mod))
                    cipher = des_ede2(hex_2_uint64(argv[3]), hex_2_uint64(argv[4]), hex_2_uint64(argv[5]), 0);
                else
                    cipher = des_ede2(hex_2_uint64(argv[3]), hex_2_uint64(argv[4]), hex_2_uint64(argv[5]), 1);
            end = clock();
            duration = (double)(end - start) / (double)(CLOCKS_PER_SEC);
            printf("%llx\n", cipher);
            printf("enc/dec for 1000 times cost: %f s\n", duration);
        }
    }
    system("pause");
}