Created
September 23, 2017 17:23
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Simple encryption / decryption utility class which uses openssl. Be sure to supply a strong cryptographic key. Change method as you see fit.
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<?php | |
/** | |
* Static class for simple encryption and decryption utilities. | |
*/ | |
class Cryptor { | |
// This key is used if one is not supplied during encryption / decryption. | |
private const UNIQUE_KEY = '<some default key here>'; | |
private const METHOD = 'AES-256-CTR'; | |
public static function encrypt($text, $key = null) { | |
if (self::isSupported()) { | |
$ivlen = openssl_cipher_iv_length(self::METHOD); | |
$iv = openssl_random_pseudo_bytes($ivlen); | |
$keyVal = is_string($key) ? $key : self::UNIQUE_KEY; | |
$ciphertext_raw = openssl_encrypt($text, self::METHOD, $keyVal, $options = OPENSSL_RAW_DATA, $iv); | |
$hmac = hash_hmac('sha256', $ciphertext_raw, $keyVal, $as_binary = true); | |
return base64_encode($iv.$hmac.$ciphertext_raw); | |
} else { | |
throw new Exception("This environment doesn't support this kind of encryption."); | |
} | |
} | |
public static function decrypt($text, $key = null) { | |
if (self::isSupported()) { | |
$baseDecodedText = base64_decode($text); | |
$ivlen = openssl_cipher_iv_length(self::METHOD); | |
$iv = substr($baseDecodedText, 0, $ivlen); | |
$hmac = substr($baseDecodedText, $ivlen, $sha2len = 32); | |
$ciphertext_raw = substr($baseDecodedText, $ivlen+$sha2len); | |
$keyVal = is_string($key) ? $key : self::UNIQUE_KEY; | |
$original_plaintext = openssl_decrypt($ciphertext_raw, self::METHOD, $keyVal, $options = OPENSSL_RAW_DATA, $iv); | |
$calcmac = hash_hmac('sha256', $ciphertext_raw, $keyVal, $as_binary = true); | |
if (hash_equals($hmac, $calcmac)) { | |
return $original_plaintext; | |
} else { | |
return false; | |
} | |
} else { | |
throw new Exception("This environment doesn't support this kind of decryption."); | |
} | |
} | |
public static function isSupported() { | |
return (extension_loaded('openssl') && function_exists('openssl_encrypt')); | |
} | |
} |
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