c - AES 256 程序不工作

标签 c encryption aes encryption-symmetric

<分区>

所以我一直在尝试用 C 语言实现 AES-256。经过大量阅读并按照维基百科页面进行实现后，我设法编写了代码。只有当我测试它时，它似乎给出了错误的输出。

代码:

/*
AES-256
(c) 2017 Daniel Gee
*/

#include <stdio.h>
#include <stdlib.h>

unsigned char rcon[256] = {
    0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 
    0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 
    0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 
    0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 
    0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 
    0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 
    0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 
    0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 
    0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 
    0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 
    0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 
    0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 
    0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 
    0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 
    0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 
    0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d
};

unsigned char sbox[256] = {
    0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
    0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
    0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
    0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
    0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
    0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
    0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
    0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
    0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
};

void rotate(unsigned char *w){
    unsigned char t;
    t = w[0];
    w[0] = w[1];
    w[1] = w[2];
    w[2] = w[3];
    w[3] = t;
}

void key_schedule_core(unsigned char *w, unsigned char i){
    unsigned char j;
    rotate(w);
    for(j = 0; j < 4; j++){
        w[j] = sbox[w[j]];
    }
    w[0] ^= rcon[i];
}

unsigned char *key_schedule(unsigned char *key){
    unsigned char n = 32, b = 240, *e = malloc(sizeof(unsigned char) * b), i = 1, j, k, t[4];
    for(k = 0; k < n; k++){
        e[k] = key[k];
    }
    j = 32;

    while(j < b){
        t[0] = e[j - 4];
        t[1] = e[j - 3];
        t[2] = e[j - 2];
        t[3] = e[j - 1];

        key_schedule_core(t, i);

        i++;

        t[0] ^= e[j - n];
        t[1] ^= e[j - n + 1];
        t[2] ^= e[j - n + 2];
        t[3] ^= e[j - n + 3];

        e[j] = t[0];
        e[j + 1] = t[1];
        e[j + 2] = t[2];
        e[j + 3] = t[3];
        j += 4;

        for(k = 0; k < 3; k++){
            t[0] = e[j - 4];
            t[1] = e[j - 3];
            t[2] = e[j - 2];
            t[3] = e[j - 1];

            t[0] ^= e[j - n];
            t[1] ^= e[j - n + 1];
            t[2] ^= e[j - n + 2];
            t[3] ^= e[j - n + 3];

            e[j] = t[0];
            e[j + 1] = t[1];
            e[j + 2] = t[2];
            e[j + 3] = t[3];

            j += 4;
        }

        t[0] = e[j - 4];
        t[1] = e[j - 3];
        t[2] = e[j - 2];
        t[3] = e[j - 1];

        t[0] = sbox[t[0]];
        t[1] = sbox[t[1]];
        t[2] = sbox[t[2]];
        t[3] = sbox[t[3]];

        t[0] ^= e[j - n];
        t[1] ^= e[j - n + 1];
        t[2] ^= e[j - n + 2];
        t[3] ^= e[j - n + 3];

        e[j] = t[0];
        e[j + 1] = t[1];
        e[j + 2] = t[2];
        e[j + 3] = t[3];

        j += 4;

        if(j > b){
            break;
        }

        for(k = 0; k < 3; k++){
            t[0] = e[j - 4];
            t[1] = e[j - 3];
            t[2] = e[j - 2];
            t[3] = e[j - 1];

            t[0] ^= e[j - n];
            t[1] ^= e[j - n + 1];
            t[2] ^= e[j - n + 2];
            t[3] ^= e[j - n + 3];

            e[j] = t[0];
            e[j + 1] = t[1];
            e[j + 2] = t[2];
            e[j + 3] = t[3];

            j += 4;
        }
    }

    return e;
}

void shift_rows(unsigned char *state){
    unsigned char t;
    t = state[4];
    state[4] = state[5];
    state[5] = state[6];
    state[6] = state[7];
    state[7] = t;

    t = state[8];
    state[10] = t;
    t = state[9];
    state[11] = t;

    t = state[12];
    state[12] = state[15];
    state[15] = state[14];
    state[14] = state[13];
    state[13] = t;
}

void mix_columns(unsigned char *state){
    unsigned char a[4], b[4], c, j;
    for(j = 0; j < 4; j++){
        for(c = 0; c < 4; c++){
            a[c] = state[(j * 4) + c];
            b[c] = state[(j * 4) + c] << 1;
            if(state[(j * 4) + c] & 0x80){
                b[c] ^= 0x1b;
            }
        }
        state[(j * 4) + 0] = b[0] ^ a[3] ^ a[2] ^ b[1] ^ a[1];
        state[(j * 4) + 1] = b[1] ^ a[0] ^ a[3] ^ b[2] ^ a[2];
        state[(j * 4) + 2] = b[2] ^ a[1] ^ a[0] ^ b[3] ^ a[3];
        state[(j * 4) + 3] = b[3] ^ a[2] ^ a[1] ^ b[0] ^ a[0];
    }
}

void encrypt(unsigned char *key, unsigned char *state){
    unsigned char *e = key_schedule(key), i, j;
    for(i = 0; i < 14; i++){
        if(i == 0){
            for(j = 0; j < 16; j++){
                state[j] ^= e[(i * 16) + j];
            }
        }else if(i == 13){
            for(j = 0; j < 16; j++){
                state[j] ^= sbox[state[j]];
            }
            shift_rows(state);
            for(j = 0; j < 16; j++){
                state[j] ^= e[(i * 16) + j];
            }
        }else{
            for(j = 0; j < 16; j++){
                state[j] ^= sbox[state[j]];
            }
            shift_rows(state);
            mix_columns(state);
            for(j = 0; j < 16; j++){
                state[j] ^= e[(i * 16) + j];
            }
        }
    }
}

int main(){
    unsigned char key[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
        message[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

    encrypt(key, message);

    for(int i = 0; i < 16; i++){
        printf("%02x ", message[i]);
    }
    printf("\n");
}

例子:

key = 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
message = 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
output = c2 2a 26 68 a8 4a 1e f3 ac 40 23 05 25 50 00 02

最佳答案

“The Design of Rijndael”一书 (ISBN 3-540-42580-2) 在附录 D 中有一个很棒的测试 vector 列表，用于 AES 128 加密的所有中间步骤。单步执行您的代码并将您的结果与书中的结果进行比较。暂时将您的代码更改为 AES-128 以查找错误然后再将其切换回 AES-256 应该很容易。

在那之后，放弃你的实现并使用已经过全面测试的既定实现，因为你的实现很容易受到定时攻击(因为 if(state[(j * 4) + c] & 0x80) )，这允许攻击者找出 key 。为避免此问题和其他实现错误，请查阅有关实现密码学的书籍，并尝试尽可能多地使用现有代码，而不是编写自己的代码。

关于c - AES 256 程序不工作，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42072835/

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