PHP Extension

AES 256-bit CBC using PBKDF2 Generated Secret Key

See more Encryption Examples

First generates a 32-byte secret key using PBKDF2 (with HMAC-SHA256), and then uses the secret key to do 256-bit AES CBC mode decryption.

(Duplicates the following Java code)

public String decrypt(String strToDecrypt) {
        try  {
            // Read the initialization vector from the first bytes for the data
            byte [] rawData = Base64.getDecoder().decode(strToDecrypt);
            byte [] iv = new byte[Config.get().encryptionIVLength()];
            byte [] encryptedData = new byte[rawData.length - iv.length];
            System.arraycopy(rawData, 0, iv, 0, iv.length);
            System.arraycopy(rawData, iv.length, encryptedData, 0, encryptedData.length);
 
            IvParameterSpec ivspec = new IvParameterSpec(iv);
 
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
            KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), salt.getBytes(), 65536, 256);
            SecretKey tmp = factory.generateSecret(spec);
            SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");
 
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
            cipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec);
            return new String(cipher.doFinal(encryptedData));
        }
        catch (Exception e) {
            log.error("Could not decrypt the string.", e);
        }
        return null;
    }

PHP Extension

<?php

include("chilkat.php");

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

$crypt = new CkCrypt2();

$password = 'some arbitrary length password';
// We have 8 bytes of salt encoded using hex.
// (The salt can be any number of bytes, in any desired encoding such as base64, hex, etc.)
$saltHex = '0102030405060708';

// Generate the 256-bit (32-byte) AES secret key we'll use to decrypt.
$iterationCount = 65536;
$outputKeyBitLen = 256;
$secretKeyHex = $crypt->pbkdf2($password,'utf-8','sha256',$saltHex,$iterationCount,$outputKeyBitLen,'hex');

// Setup for 256-bit AES CBC decryption.
$crypt->put_CryptAlgorithm('aes');
$crypt->put_KeyLength(256);
$crypt->put_CipherMode('cbc');
$crypt->put_PaddingScheme(0);

// The IV for AES is 16 bytes.
$iv = '000102030405060708090A0B0C0D0E0F';
$crypt->SetEncodedIV($iv,'hex');

// Set the secret key for 256-bit AES.
$crypt->SetEncodedKey($secretKeyHex,'hex');

// AES decrypt
// assume our string to decrypt is base64
$strToDecrypt = '....';
$crypt->put_EncodingMode('base64');
$decryptedStr = $crypt->decryptStringENC($strToDecrypt);

print $decryptedStr . "\n";

?>