<?php

namespace Zotlabs\Lib;

use Exception;

class Crypto {

	public static $openssl_algorithms = [

		// zot6 nickname,   opensslname,   keylength, ivlength

		['aes256ctr', 'aes-256-ctr', 32, 16],
		['camellia256cfb', 'camellia-256-cfb', 32, 16],
		['cast5cfb', 'cast5-cfb', 16, 8],
		['aes256cbc', 'aes-256-cbc', 32, 16] // remove after legacy zot has been sunset

	];

	public static function methods() {
		$ret = [];

		foreach (self::$openssl_algorithms as $ossl) {
			$ret[] = $ossl[0] . '.oaep';
		}

		call_hooks('crypto_methods', $ret);
		return $ret;
	}

	public static function signing_methods() {

		$ret = ['sha256'];
		call_hooks('signing_methods', $ret);
		return $ret;

	}

	public static function new_keypair($bits) {

		$openssl_options = [
			'digest_alg'       => 'sha1',
			'private_key_bits' => $bits,
			'encrypt_key'      => false
		];

		$conf = get_config('system', 'openssl_conf_file');

		if ($conf) {
			$openssl_options['config'] = $conf;
		}

		$result = openssl_pkey_new($openssl_options);

		if (empty($result)) {
			return false;
		}

		// Get private key

		$response = ['prvkey' => '', 'pubkey' => ''];

		openssl_pkey_export($result, $response['prvkey']);

		// Get public key
		$pkey               = openssl_pkey_get_details($result);
		$response['pubkey'] = $pkey["key"];

		return $response;

	}

	public static function sign($data, $key, $alg = 'sha256') {

		if (!$key) {
			return false;
		}

		$sig = '';
		openssl_sign($data, $sig, $key, $alg);
		return $sig;
	}

	public static function verify($data, $sig, $key, $alg = 'sha256') {

		if (!$key) {
			return false;
		}

		if (!$alg) {
			$alg = 'sha256';
		}

		try {
			$verify = openssl_verify($data, $sig, $key, $alg);
		} catch (Exception $e) {
			$verify = (-1);
		}

		if ($verify === (-1)) {
			while ($msg = openssl_error_string()) {
				logger('openssl_verify: ' . $msg, LOGGER_NORMAL, LOG_ERR);
			}
			btlogger('openssl_verify: key: ' . $key, LOGGER_DEBUG, LOG_ERR);
		}

		return (($verify > 0) ? true : false);
	}

	public static function encapsulate($data, $pubkey, $alg) {

		if (!($alg && $pubkey)) {
			return $data;
		}

		$alg_base = $alg;
		$padding  = OPENSSL_PKCS1_PADDING;

		$exts = explode('.', $alg);
		if (count($exts) > 1) {
			switch ($exts[1]) {
				case 'oaep':
					$padding = OPENSSL_PKCS1_OAEP_PADDING;
					break;
				default:
					break;
			}
			$alg_base = $exts[0];
		}

		$method = null;

		foreach (self::$openssl_algorithms as $ossl) {
			if ($ossl[0] === $alg_base) {
				$method = $ossl;
				break;
			}
		}

		if ($method) {
			$result = ['encrypted' => true];

			$key = openssl_random_pseudo_bytes(256);
			$iv  = openssl_random_pseudo_bytes(256);

			$key1 = substr($key, 0, $method[2]);
			$iv1  = substr($iv, 0, $method[3]);

			$result['data'] = base64url_encode(openssl_encrypt($data, $method[1], $key1, OPENSSL_RAW_DATA, $iv1), true);

			openssl_public_encrypt($key, $k, $pubkey, $padding);
			openssl_public_encrypt($iv, $i, $pubkey, $padding);

			$result['alg'] = $alg;
			$result['key'] = base64url_encode($k, true);
			$result['iv']  = base64url_encode($i, true);
			return $result;

		}
		else {
			$x = ['data' => $data, 'pubkey' => $pubkey, 'alg' => $alg, 'result' => $data];
			call_hooks('crypto_encapsulate', $x);
			return $x['result'];
		}
	}

	public static function unencapsulate($data, $prvkey) {

		if (!(is_array($data) && array_key_exists('encrypted', $data) && array_key_exists('alg', $data) && $data['alg'])) {
			logger('not encrypted');

			return $data;
		}

		$alg_base = $data['alg'];
		$padding  = OPENSSL_PKCS1_PADDING;

		$exts = explode('.', $data['alg']);
		if (count($exts) > 1) {
			switch ($exts[1]) {
				case 'oaep':
					$padding = OPENSSL_PKCS1_OAEP_PADDING;
					break;
				default:
					break;
			}
			$alg_base = $exts[0];
		}

		$method = null;

		foreach (self::$openssl_algorithms as $ossl) {
			if ($ossl[0] === $alg_base) {
				$method = $ossl;
				break;
			}
		}

		if ($method) {
			openssl_private_decrypt(base64url_decode($data['key']), $k, $prvkey, $padding);
			openssl_private_decrypt(base64url_decode($data['iv']), $i, $prvkey, $padding);
			return openssl_decrypt(base64url_decode($data['data']), $method[1], substr($k, 0, $method[2]), OPENSSL_RAW_DATA, substr($i, 0, $method[3]));
		}
		else {
			$x = ['data' => $data, 'prvkey' => $prvkey, 'alg' => $data['alg'], 'result' => $data];
			call_hooks('crypto_unencapsulate', $x);
			return $x['result'];
		}
	}
}
