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Add cryptor code and example.
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‎cryptor.php‎

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<?php
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/**
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* Simple example of using the openssl encrypt/decrypt functions that
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* are inadequately documented in the PHP manual.
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*
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* Available under the MIT License
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*
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* The MIT License (MIT)
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* Copyright (c) 2016 ionCube Ltd.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
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* documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all copies or substantial portions of
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* the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
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* THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
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* OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
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* OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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class Cryptor
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{
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private $cipher_algo;
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private $hash_algo;
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private $iv_num_bytes;
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private $format;
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const FORMAT_RAW = 0;
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const FORMAT_B64 = 1;
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const FORMAT_HEX = 2;
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/**
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* Construct a Cryptor, using aes256 encryption, sha256 key hashing and base64 encoding.
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* @param string $cipher_algo The cipher algorithm.
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* @param string $hash_algo Key hashing algorithm.
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* @param [type] $fmt Format of the encrypted data.
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*/
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public function __construct($cipher_algo = 'aes-256-ctr', $hash_algo = 'sha256', $fmt = Cryptor::FORMAT_B64)
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{
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$this->cipher_algo = $cipher_algo;
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$this->hash_algo = $hash_algo;
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$this->format = $fmt;
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if (!in_array($cipher_algo, openssl_get_cipher_methods(true)))
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{
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throw new \Exception("Cryptor:: - unknown cipher algo {$cipher_algo}");
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}
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if (!in_array($hash_algo, openssl_get_md_methods(true)))
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{
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throw new \Exception("Cryptor:: - unknown hash algo {$hash_algo}");
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}
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$this->iv_num_bytes = openssl_cipher_iv_length($cipher_algo);
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}
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/**
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* Encrypt a string.
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* @param string $in String to encrypt.
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* @param string $key Encryption key.
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* @param int $fmt Optional override for the output encoding. One of FORMAT_RAW, FORMAT_B64 or FORMAT_HEX.
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* @return string The encrypted string.
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*/
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public function encryptString($in, $key, $fmt = null)
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{
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if ($fmt === null)
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{
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$fmt = $this->format;
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}
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// Build an initialisation vector
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$iv = mcrypt_create_iv($this->iv_num_bytes, MCRYPT_DEV_URANDOM);
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// Hash the key
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$keyhash = openssl_digest($key, $this->hash_algo, true);
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// and encrypt
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$opts = OPENSSL_RAW_DATA;
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$encrypted = openssl_encrypt($in, $this->cipher_algo, $keyhash, $opts, $iv);
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if ($encrypted === false)
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{
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throw new \Exception('Cryptor::encryptString() - Encryption failed: ' . openssl_error_string());
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}
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// The result comprises the IV and encrypted data
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$res = $iv . $encrypted;
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// and format the result if required.
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if ($fmt == Cryptor::FORMAT_B64)
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{
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$res = base64_encode($res);
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}
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else if ($fmt == Cryptor::FORMAT_HEX)
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{
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$res = unpack('H*', $res)[1];
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}
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return $res;
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}
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/**
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* Decrypt a string.
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* @param string $in String to decrypt.
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* @param string $key Decryption key.
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* @param int $fmt Optional override for the input encoding. One of FORMAT_RAW, FORMAT_B64 or FORMAT_HEX.
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* @return string The decrypted string.
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*/
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public function decryptString($in, $key, $fmt = null)
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{
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if ($fmt === null)
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{
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$fmt = $this->format;
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}
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$raw = $in;
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// Restore the encrypted data if encoded
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if ($fmt == Cryptor::FORMAT_B64)
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{
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$raw = base64_decode($in);
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}
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else if ($fmt == Cryptor::FORMAT_HEX)
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{
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$raw = pack('H*', $in);
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}
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// and do an integrity check on the size.
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if (strlen($raw) < $this->iv_num_bytes)
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{
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throw new \Exception('Cryptor::decryptString() - ' .
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'data length ' . strlen($raw) . " is less than iv length {$this->iv_num_bytes}");
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}
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// Extract the initialisation vector and encrypted data
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$iv = substr($raw, 0, $this->iv_num_bytes);
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$raw = substr($raw, $this->iv_num_bytes);
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// Hash the key
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$keyhash = openssl_digest($key, $this->hash_algo, true);
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// and decrypt.
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$opts = OPENSSL_RAW_DATA;
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$res = openssl_decrypt($raw, $this->cipher_algo, $keyhash, $opts, $iv);
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if ($res === false)
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{
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throw new \Exception('Cryptor::decryptString - decryption failed: ' . openssl_error_string());
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}
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return $res;
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}
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/**
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* Static convenience method for encrypting.
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* @param string $in String to encrypt.
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* @param string $key Encryption key.
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* @param int $fmt Optional override for the output encoding. One of FORMAT_RAW, FORMAT_B64 or FORMAT_HEX.
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* @return string The encrypted string.
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*/
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public static function Encrypt($in, $key, $fmt = null)
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{
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$c = new Cryptor();
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return $c->encryptString($in, $key, $fmt);
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}
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/**
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* Static convenience method for decrypting.
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* @param string $in String to decrypt.
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* @param string $key Decryption key.
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* @param int $fmt Optional override for the input encoding. One of FORMAT_RAW, FORMAT_B64 or FORMAT_HEX.
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* @return string The decrypted string.
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*/
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public static function Decrypt($in, $key, $fmt = null)
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{
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$c = new Cryptor();
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return $c->decryptString($in, $key, $fmt);
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}
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}

‎example.php‎

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<?php
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include_once 'cryptor.php';
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$data = 'Good things come in small packages.';
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$key = '9901:io=[<>602vV03&Whb>9J&M~Oq';
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$encrypted = Cryptor::Encrypt($data, $key);
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echo "'$data' (" . strlen($data) . ") => '$encrypted'\n\n";
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$decrypted = Cryptor::Decrypt($encrypted, $key);
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echo "'$encrypted' => '$decrypted' (" . strlen($decrypted) . ")\n";

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