(PHP Extension) Duplicate PHP's openssl_encrypt and openssl_random_pseudo_bytes

Demonstrates how to duplicate PHP's openssl_encrypt function. (https://www.php.net/manual/en/function.openssl-encrypt.php)

For more information, see https://www.php.net/manual/en/function.openssl-encrypt.php

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux, Solaris

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

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

// Duplicates thw following PHP script:

// $text = "This is a test";
// $passphrase = "my password";
// $iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length("AES-256-CBC"));
// $crypted = base64_encode($iv.openssl_encrypt($text, "AES-256-CBC", $passphrase, OPENSSL_RAW_DATA, $iv));
// echo $crypted;

$crypt = new CkCrypt2();

$text = 'This is a test';
$passphrase = 'my password';

// AES is a block cipher.  The IV size for any block cipher is the size of the block, which is defined by the encryption algorithm. 
// For AES, the block size is always 16 bytes, regardless of key size (i.e. 128-bits, 192-bits, or 256-bits).
// Therefore, generate 16 random bytes for the IV.
$crypt->put_EncodingMode('base64');
$ivBase64 = $crypt->genRandomBytesENC(16);

print 'Generated IV = ' . $ivBase64 . "\n";

// Because we're doing AES-256-CBC, the key length must be 256-bits (i.e. 32 bytes).
// Given that our passphrase is a us-ascii string that can be shorter or longer than 32-bytes, we need to 
// somehow transform the passphrase to a 32-byte secret key.  We need to know what openssl_encrypt does.
// Here's the answer from the openssl_encrypt documentation:
// 
// "If the passphrase is shorter than expected, it is silently padded with NUL characters; 
// if the passphrase is longer than expected, it is silently truncated."

// OK.... so let's pad or shorten to get a 32-byte key.
$bdKey = new CkBinData();
$bdKey->AppendString($passphrase,'utf-8');

$sz = $bdKey->get_NumBytes();
if ($sz > 32) {
    $bdKey->RemoveChunk(32,$sz - 32);
}
else {
    $bdKey->Clear();
    $bdKey->AppendPadded($passphrase,'utf-8',false,32);
}

// Setup for encryption.
$crypt->put_CryptAlgorithm('aes');
$crypt->put_KeyLength(256);
$crypt->SetEncodedIV($ivBase64,'base64');
$crypt->SetEncodedKey($bdKey->getEncoded('base64'),'base64');

// Encrypt and base64 encode.
$cipherText64 = $crypt->encryptStringENC($text);

// The PHP code fragment above returns the base64 encoded bytes of the IV and the encrypted text.
// So let's do that..
$bd = new CkBinData();
$bd->AppendEncoded($ivBase64,'base64');
$bd->AppendEncoded($cipherText64,'base64');
$result = $bd->getEncoded('base64');

print 'result = ' . $result . "\n";

// Sample output:
// dN0vS1O0cWi5BbLAAY+NTf7bs3S27xzPf11RkG47sjs=

// Now let's decrypt from the output...

// Setup for decryption.
$crypt->put_CryptAlgorithm('aes');
$crypt->put_KeyLength(256);
$crypt->SetEncodedKey($bdKey->getEncoded('base64'),'base64');

$bdResult = new CkBinData();
$bdResult->AppendEncoded($result,'base64');
$crypt->SetEncodedIV($bdResult->getEncodedChunk(0,16,'base64'),'base64');

// Remove the IV (first 16 bytes) from the result.
$bdResult->RemoveChunk(0,16);
$success = $crypt->DecryptBd($bdResult);
$originalText = $bdResult->getString('utf-8');

print 'original text = ' . $originalText . "\n";

?>