(PHP Extension) AES Encrypt and Decrypt a File

PHP Extension demonstrates how to AES encrypt a file of any size, and then decrypt.

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.

$crypt = new CkCrypt2();

$crypt->put_CryptAlgorithm('aes');

// CipherMode may be "ecb" or "cbc"
$crypt->put_CipherMode('cbc');

// KeyLength may be 128, 192, 256
$crypt->put_KeyLength(256);

// The padding scheme determines the contents of the bytes
// that are added to pad the result to a multiple of the
// encryption algorithm's block size.  AES has a block
// size of 16 bytes, so encrypted output is always
// a multiple of 16.
$crypt->put_PaddingScheme(0);

// An initialization vector is required if using CBC mode.
// ECB mode does not use an IV.
// The length of the IV is equal to the algorithm's block size.
// It is NOT equal to the length of the key.
$ivHex = '000102030405060708090A0B0C0D0E0F';
$crypt->SetEncodedIV($ivHex,'hex');

// The secret key must equal the size of the key.  For
// 256-bit encryption, the binary secret key is 32 bytes.
// For 128-bit encryption, the binary secret key is 16 bytes.
$keyHex = '000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F';
$crypt->SetEncodedKey($keyHex,'hex');

// Encrypt a file, producing the .aes as output.
// The input file is unchanged, the output .aes contains the encrypted
// contents of the input file.

// Note: The .aes output file has no file format.  It is simply a stream
// of bytes that resembles random binary data.
$inFile = '/Users/chilkat/testData/pdf/sample.pdf';
$outFile = '/Users/chilkat/testData/p7m/sample.pdf.aes';
$success = $crypt->CkEncryptFile($inFile,$outFile);
if ($success != true) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

// For demonstration purposes, a different instance of the object will be used
// for decryption.
$decrypt = new CkCrypt2();

// All settings must match to be able to decrypt:
$decrypt->put_CryptAlgorithm('aes');
$decrypt->put_CipherMode('cbc');
$decrypt->put_KeyLength(256);
$decrypt->put_PaddingScheme(0);
$decrypt->SetEncodedIV($ivHex,'hex');
$decrypt->SetEncodedKey($keyHex,'hex');

// Decrypt the .aes
$inFile = '/Users/chilkat/testData/p7m/sample.pdf.aes';
$outFile = '/Users/chilkat/testData/pdf/recovered.pdf';
$success = $decrypt->CkDecryptFile($inFile,$outFile);
if ($success == false) {
    print $decrypt->lastErrorText() . "\n";
    exit;
}

print 'Success!' . "\n";

?>