PHP

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.

Chilkat2 PHP

<?php

use Chilkat2\BinData;
use Chilkat2\Crypt2;

// 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 = new BinData();
$bd->AppendEncoded('2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0', 'hex');

$crypt = new Crypt2();

$crypt->CryptAlgorithm = 'aes';
$crypt->CipherMode = 'xts';
$crypt->KeyLength = 128;

$crypt->SetEncodedKey($key, 'hex');
$crypt->XtsSetEncodedTweakKey($tweakKey, 'hex');
$crypt->XtsSetEncodedTweakValue($dataUnit, 'hex');

// In-place encrypt the contents of bd.
$crypt->EncryptBd($bd);

echo 'CT = ', $bd->GetEncoded('hexlower'), "\n";

// Decrypt to revert back to the unencrypted content:
$crypt->DecryptBd($bd);

echo 'PT = ', $bd->GetEncoded('hexlower'), "\n";

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