C

AES XTS Mode

See more Encryption Examples

Demonstrates the AES-XTS mode of operation.

Note: This example requires Chilkat v9.5.0.91 or greater.

C

#include <C_CkBinData.h>
#include <C_CkCrypt2.h>

void ChilkatSample(void)
    {
    BOOL success;
    const char *key;
    const char *tweakKey;
    const char *dataUnit;
    HCkBinData bd;
    HCkCrypt2 crypt;

    success = FALSE;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Here we have a sample from CAVS validatition data:

    // COUNT = 301
    // DataUnitLen = 200
    // Key = 
    // 394c97881abd989d29c703e48a72b397
    // a7acf51b59649eeea9b33274d8541df4
    // i = 4b15c684a152d485fe9937d39b168c29
    // PT = 2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0
    // CT = f3473802e38a3ffef4d4fb8e6aa266ebde553a64528a06463e

    // Note: The above sample requires an AES-XTS implementation that fully supports ciphertext-stealing
    // because the data to be encrypted is not an even multiple of the AES block size (i.e. not a multiple of 16 bytes).
    // Chilkat fully supports AES-XTS with ciphertext stealing.
    // (i.e. Chilkat implements XEX-based tweaked-codebook mode with ciphertext stealing (XTS))

    key = "394c97881abd989d29c703e48a72b397";
    tweakKey = "a7acf51b59649eeea9b33274d8541df4";
    dataUnit = "4b15c684a152d485fe9937d39b168c29";

    bd = CkBinData_Create();
    CkBinData_AppendEncoded(bd,"2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0","hex");

    crypt = CkCrypt2_Create();

    CkCrypt2_putCryptAlgorithm(crypt,"aes");
    CkCrypt2_putCipherMode(crypt,"xts");
    CkCrypt2_putKeyLength(crypt,128);

    CkCrypt2_SetEncodedKey(crypt,key,"hex");
    CkCrypt2_XtsSetEncodedTweakKey(crypt,tweakKey,"hex");
    CkCrypt2_XtsSetEncodedTweakValue(crypt,dataUnit,"hex");

    // In-place encrypt the contents of bd.
    success = CkCrypt2_EncryptBd(crypt,bd);

    printf("CT = %s\n",CkBinData_getEncoded(bd,"hexlower"));

    // Decrypt to revert back to the unencrypted content:
    success = CkCrypt2_DecryptBd(crypt,bd);

    printf("PT = %s\n",CkBinData_getEncoded(bd,"hexlower"));

    // Output:
    // CT = f3473802e38a3ffef4d4fb8e6aa266ebde553a64528a06463e
    // PT = 2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0


    CkBinData_Dispose(bd);
    CkCrypt2_Dispose(crypt);

    }