Encrypt & Decrypt with PHP

decrypt.php

<?php
/**
 * Decrypts a value.
 *
 * If a user-based key is set, that key is used. Otherwise the default key is used.
 *
 * @since 1.0.0
 *
 * @param string $raw_value Value to decrypt.
 * @param string $key Key to use for encryption.
 * @param string $salt Salt to use for encryption.
 * @return string|bool Decrypted value, or false on failure.
 */
function decrypt( $raw_value, $key, $salt ) {
	if ( ! extension_loaded( 'openssl' ) ) {
		return $raw_value;
	}

	$raw_value = base64_decode( $raw_value, true ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_decode

	$method = 'aes-256-ctr';
	$ivlen  = openssl_cipher_iv_length( $method );
	$iv     = substr( $raw_value, 0, $ivlen );

	$raw_value = substr( $raw_value, $ivlen );

	$value = openssl_decrypt( $raw_value, $method, $key, 0, $iv );
	if ( ! $value || substr( $value, - strlen( $salt ) ) !== $salt ) {
		return false;
	}

	return substr( $value, 0, - strlen( $this->salt ) );
}

encrypt.php

<?php
/**
 * Encrypts a value.
 *
 * If a user-based key is set, that key is used. Otherwise the default key is used.
 *
 * @since 1.0.0
 *
 * @param string $value Value to encrypt.
 * @param string $key Key to use for encryption.
 * @param string $salt Salt to use for encryption.
 * @return string|bool Encrypted value, or false on failure.
 */
function encrypt( $value, $key, $salt ) {
	if ( ! extension_loaded( 'openssl' ) ) {
		return $value;
	}

	$method = 'aes-256-ctr';
	$ivlen  = openssl_cipher_iv_length( $method );
	$iv     = openssl_random_pseudo_bytes( $ivlen );

	$raw_value = openssl_encrypt( $value . $salt, $method, $key, 0, $iv );
	if ( ! $raw_value ) {
		return false;
	}

	return base64_encode( $iv . $raw_value ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode
}