kpcrypt/lib.php

<?php
/**
 * @param string $data The data to be encrypted, this can only encrypt strings.
 * @param string $key The key to use to encrypt the data, this key should be generated using the openssl_random_pseudo_bytes
 * @param string $cipherMethod The cypher method to use in the encryption process, these can be checked using 
 * @param bool $integrity_check Check if the encrypted data can also be decypted, this will take 2x more time to process the data, but will make 100% sure that the data is safe and can be decrypted.
 */
function encryptData( string $data, string $key, string $cipherMethod = 'AES-256-CBC', bool $integrity_check = TRUE) {

    // Lowercase the cipher
    $cipherMethod = strtolower($cipherMethod);

    // Check if the encryption method is valid
    if (!in_array($cipherMethod, openssl_get_cipher_methods())) {
        // Cypher was not in the available ciphers list.
        return FALSE;
    }

    // To encrypt a string   
    $iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length($cipherMethod));

    // Encrypt the data
    $encryptedData = openssl_encrypt($data, $cipherMethod, $key, OPENSSL_RAW_DATA, $iv);

    // Append the iv to the encrypted data
    $encryptedData = $iv . $encryptedData;

    // base64 encrypt to make sure we don't lose bytes
    $encryptedData = base64_encode($encryptedData);

    // Check if we should verify the integrity of the encryption
    if ( $integrity_check === TRUE ) {
        // Test for decryption validity
        if ( md5(decryptData($encryptedData, $key, $cipherMethod)) === md5($data) ) {
            // Put the output in the result
            return $encryptedData;
        } else {
            // Assign the output to the result
            return FALSE;
        }
    } else {
        // Simply return the results
        return $encryptedData;
    }

}

/**
 * @param string $data The data to be encrypted, this can only encrypt strings.
 * @param string $key The key to use to encrypt the data, this key should be generated using the openssl_random_pseudo_bytes
 * @param string $cipherMethod The cypher method to use in the encryption process, these can be checked using 
 */
function decryptData( string $data, string $key, string $cipherMethod = 'AES-256-CBC' ) {

    // Lowercase the cipher
    $cipherMethod = strtolower($cipherMethod);

    // Check if the encryption method is valid
    if (!in_array($cipherMethod, openssl_get_cipher_methods())) {
        // Cypher was not in the available ciphers list.
        return FALSE;
    }

    // base64 decode the data.
    $data = base64_decode($data);

    // Get the length of the IV
    $iv_length = openssl_cipher_iv_length($cipherMethod);
    // Get the IV from the decoded data
    $iv = substr($data,0,$iv_length);

    // Get the encrypted string from the data
    $data = substr($data, $iv_length);

    // Decrypt the data
    $data = openssl_decrypt($data,$cipherMethod,$key, OPENSSL_RAW_DATA, $iv);

    // Return the data
    return $data;
}