<?php

namespace Zotlabs\Lib;
use Exception;

class Crypto {

	static public $openssl_algorithms = [

		// zot6 nickname,   opensslname,   keylength, ivlength

		[ 'aes256ctr',      'aes-256-ctr',      32, 16 ],
		[ 'camellia256cfb', 'camellia-256-cfb', 32, 16 ],
		[ 'cast5cfb',       'cast5-cfb',        16, 8  ]

	];


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

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

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


	static public function signing_methods() {

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

	}


	static public 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;

	}


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

		if (! $key) {
			return false;
		}

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


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

		if (! $key) {
			return false;
		}

		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);
	}

	static public 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'];
		}
	}

	static public 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'];
		}
	}
}