Question

下面显示的代码是带有CBC模式实现的AES。我对网络安全方面很陌生。我想知道如何在块上添加mac生成函数并使其成为cbc-mac

 static void GenerateDecryptionKey(uint8_t *key)
{
CRYCONLbits.CRYON = 0b1;        //Turn module on
CRYCONHbits.KEYSRC = 0b000;    //Select the key source (CRYKEY)
CRYCONLbits.OPMOD = 0b0010;     //Select the operational mode (AES Decryption Key Expansion)
CRYCONLbits.CPHRSEL = 0b1;      //Select the cipher (AES)
//(AES decryption key generation)
CRYCONHbits.KEYMOD = 0b00;      //Set the key strength (128-bit key)
memcpy((void *)&CRYKEY0, key, 16); //Load the key into CRYKEY
//(128-bit key in this example)
CRYCONLbits.CRYGO = 0b1;        //Start the encryption
while (CRYCONLbits.CRYGO == 0b1)
    ;
  }

 // For 128-bit key and 128-bit block size
 void EncryptBlocks(
    CIPHER_MODE mode,
    uint8_t *key,
    uint8_t *iv,
    uint8_t *plaintext,
    uint8_t *ciphertext,
    int numblocks)
 {
CRYCONLbits.CRYON   = 1; //Turn module on
CRYCONHbits.KEYSRC  = 0b0000;     //Select the key source (CRYKEY)
CRYCONLbits.OPMOD   = 0b0000;     //Select operational mode (Encryption)
CRYCONLbits.CPHRSEL = 1;          //Select cipher engine (AES)
CRYCONLbits.CPHRMOD = 0b001 ;       //Select encryption mode
CRYCONHbits.KEYMOD  = 0;          //Set key strength to 128-bit

memcpy((void*)&CRYKEY0, key, 16); //Load the 128-bit key into CRYKEY

memcpy((void*)&CRYTXTB0, iv, 16); //Load the 128-bit initial vector (IV)


int i;
for (i = 0; i < numblocks; i += 16) {

    //Load the next plaintext block into CRYTXTA
    memcpy((void*)&CRYTXTA0, plaintext+ i, 16);

    //Start the encryption
    CRYCONLbits.CRYGO = 0b1;

    // Wait for completion
    while (CRYCONLbits.CRYGO == 0b1)
        ;

    //Read the results out of CRYTXTB
    memcpy(ciphertext+i, (void*)&CRYTXTB0, 16);
 }
 }

// For 128-bit key and 128-bit block size
void DecryptBlocks(
    CIPHER_MODE mode,
    uint8_t *key,
    uint8_t *ciphertext,
    uint8_t *plaintext,
    int numblocks)
 {

GenerateDecryptionKey(key);
CRYCONLbits.CRYON   = 1; //Turn module on
CRYCONHbits.KEYSRC  = 0b0000;     //Select the key source (CRYKEY)
CRYCONLbits.OPMOD   = 0b0001;     //Select operational mode (Decryption)
CRYCONLbits.CPHRSEL = 1;          //Select cipher engine (AES)
CRYCONLbits.CPHRMOD = 0b001;          //Select decryption mode (CBC)

CRYCONHbits.KEYMOD  = 0;          //Set key strength to 128-bit

int i;
for (i = 0; i < numblocks; i+= 16) {

    //Load the next plaintext block into CRYTXTA
    memcpy((void*)&CRYTXTA0, plaintext+i, 16);

    //Start the encryption
    CRYCONLbits.CRYGO = 0b1;

    // Wait for completion
    while (CRYCONLbits.CRYGO == 0b1)
        ;

    //Read the results out of CRYTXTB
    memcpy(ciphertext+i, (void*)&CRYTXTB0, 16);
}
}

部分测试代码如下所示

 EncryptBlocks(mode, AES_KEY, 0, plaintext, ciphertext, numblocks);
 //EncryptBlocks(mode, AES_KEY, 0, plaintext, ciphertext, numblocks);//iv=0;  for ECB mode
//LED1 = 0;
printf("Encrypted block:");
for (i = 0; i < numblocks; i++) {
    base = i*16;
    printf("\n");
    for (j = base; j < base+16; j++) {
        printf(" %02X", ciphertext[j]);
        last[0] = ciphertext[j];
    }
}
printf("\n\n");


for (i = 0; i < 16; i++) {
    iv[i] = 0;
}
for(i=0;i<sizeof(plaintext);i++)
    plaintext[i] = 0;
DecryptBlocks(mode, AES_KEY, ciphertext, plaintext, numblocks);
printf("Decrypted block: ");


for (i = 0; i < numblocks; i++)
{
    base = i*16;
    printf("\n");
    for (j = base; j < base+16; j++) {
        printf(" %02X", plaintext[j]);
    }
}
printf("\n");
}

AES 128，C中使用CBC-MAC

0 个答案: