Question

我正在使用荨麻密码库。我无法正确执行GCM模式。这就是我的做法。我在做什么错了？

#include<iostream>
#include<nettle/gcm.h>
#include<nettle/aes.h>
using namespace std;

int main()
{
    unsigned char key[] = "1234567890123456";
    unsigned char iv[] = "123456789012";
    unsigned char src[33] = "12345678901234567890123456789012";
    unsigned char encoded[32], digest[16], datum[8] = {0,}, decoded[32];

    struct gcm_key gk, gk2;
    struct gcm_ctx gc, gc2;
    struct aes128_ctx ac, ac2;

    aes128_set_encrypt_key(&ac, key);
    gcm_set_key(&gk, &ac, (nettle_cipher_func*)aes128_encrypt);
    gcm_set_iv(&gc, &gk, 12, iv);
    gcm_update(&gc, &gk, 8, datum);
    gcm_encrypt(&gc, &gk, &ac, (nettle_cipher_func*)aes128_encrypt, 32, encoded, src);
    gcm_digest(&gc, &gk, &ac, (nettle_cipher_func*)aes128_encrypt, 16, digest);

    aes128_set_decrypt_key(&ac2, key);
    gcm_set_key(&gk2, &ac2, (nettle_cipher_func*)aes128_decrypt);
    gcm_set_iv(&gc2, &gk2, 12, iv);
    gcm_update(&gc2, &gk2, 8, datum);
    gcm_decrypt(&gc2, &gk2, &ac2, (nettle_cipher_func*)aes128_decrypt, 32, decoded, encoded);
    gcm_digest(&gc2, &gk2, &ac2, (nettle_cipher_func*)aes128_decrypt, 16, digest);

    for(unsigned char c : src) cerr << hex << +c;
    cout << endl;
    for(uint8_t c : encoded) cerr << hex << +c;
    cout << endl;
    for(uint8_t c : decoded) cerr << hex << +c;
    cout << endl;
}

，输出为

31323334353637383930313233343536373839303132333435363738393031320 80435d9ceda763309ec12a876556f72c14641344ef19fbc5c9ca2f51ebeef f064f9e8db7ae3466979c7b79de95ba6c50714023758ad9abd6eac24d6f565

第一行是源，最后一行被解码。它们不匹配。。因为我正在尝试制作一个模板包装类 GCM，我无法使用gcm-aes函数。.

Answer 1

与CTR模式类似，GCM仅使用基础密码的加密功能。因此，您需要在所有位置（分别为1和3）用aes128_set_encrypt_key和aes128_encrypt替换aes128_set_decrypt_key和aes128_decrypt。

在更改之后，您的示例对我有用。

要获得正确的身份验证，还需要比较解密后的摘要，最好使用memeql_sec。

如何使用荨麻库，GCM模式

1 个答案: