php aes 256 encryption example

encrypt.php

<?php

define('FILE_ENCRYPTION_BLOCKS', 10000);

/**
 * @param  $source  Path of the unencrypted file
 * @param  $dest  Path of the encrypted file to created
 * @param  $key  Encryption key
 */
function encryptFile($source, $dest, $key)
{
    $cipher = 'aes-256-cbc';
    $ivLenght = openssl_cipher_iv_length($cipher);
    $iv = openssl_random_pseudo_bytes($ivLenght);

    $fpSource = fopen($source, 'rb');
    $fpDest = fopen($dest, 'w');

    fwrite($fpDest, $iv);

    while (! feof($fpSource)) {
        $plaintext = fread($fpSource, $ivLenght * FILE_ENCRYPTION_BLOCKS);
        $ciphertext = openssl_encrypt($plaintext, $cipher, $key, OPENSSL_RAW_DATA, $iv);
        $iv = substr($ciphertext, 0, $ivLenght);

        fwrite($fpDest, $ciphertext);
    }

    fclose($fpSource);
    fclose($fpDest);
}


encryptFile('file.mp4', 'encrypted_file.mp4', 'my-secret-key');

echo "File encrypted!\n";
echo 'Memory usage: ' . round(memory_get_usage() / 1048576, 2) . "M\n";

thank you for your code it really helped me @};-
I had some issues with PDF so just changed the cipher from 'aes-256-cbc' to 'idea-cbc' and increased FILE_ENCRYPTION_BLOCKS to 1000000
everything works perfectly