Bug #81502 [Com]: Problem with $tag argument of openssl_decrypt()

Edit report at https://bugs.php.net/bug.php?id=81502&edit=1 ID: 81502 Comment by: alec at alec dot pl Reported by: alec at alec dot pl Summary: Problem with $tag argument of openssl_decrypt() Status: Feedback Type: Bug Package: OpenSSL related PHP Version: 8.1.0RC3 Block user comment: N Private report: N New Comment: Again, to make it clear. I want openssl_decrypt() to support null or empty string in $tag argument (as not existing) for non-AEAD ciphers. My real code is here: https://github.com/roundcube/roundcubemail/blob/318d6d08597bbfe481e01bf989150faa8c0403e5/program/lib/Roundcube/rcube.php#L894 With php8.0 I can have ($tag is null): openssl_decrypt($cipher, $method, $ckey, OPENSSL_RAW_DATA, $iv, $tag); with php8.1 it throws a deprecation warning, I cannot use this: openssl_decrypt($cipher, $method, $ckey, OPENSSL_RAW_DATA, $iv, (string) $tag); because it throws the other warning. I have to use: if ($tag === null) { openssl_decrypt($cipher, $method, $ckey, OPENSSL_RAW_DATA, $iv); } else { openssl_decrypt($cipher, $method, $ckey, OPENSSL_RAW_DATA, $iv, $tag); } which I don't like. Previous Comments: ------------------------------------------------------------------------ [2021-10-05 17:08:21] alec at alec dot pl ``` <?php ini_set('error_reporting', E_ALL); ini_set('display_errors', 'on'); function encrypt($clear) { $key = 'key'; $ckey = '123456789012345678901234'; $method = 'DES-EDE3-CBC'; $opts = OPENSSL_RAW_DATA; $iv = random_bytes(openssl_cipher_iv_length($method)); $cipher = openssl_encrypt($clear, $method, $ckey, $opts, $iv, $tag); $cipher = $iv . $cipher; return $cipher; } function decrypt($cipher) { $key = 'key'; $ckey = '123456789012345678901234'; $method = 'DES-EDE3-CBC'; $opts = OPENSSL_RAW_DATA; $iv_size = openssl_cipher_iv_length($method); $tag = null; $iv = substr($cipher, 0, $iv_size); $cipher = substr($cipher, $iv_size); return openssl_decrypt($cipher, $method, $ckey, $opts, $iv, $tag); } echo decrypt(encrypt('test')) === 'test'; ``` One correction, I'm using PHP 8.1.0RC2 on Ubuntu 18.04. ------------------------------------------------------------------------ [2021-10-05 15:17:30] nikic@php.net I can't reproduce this. Empty tag for non-AEAD cipher does not produce a warning for me and also matches my reading of the code (see https://github.com/php/php-src/blob/f313854c98e79fa5f4ec5ef9bf8755a15290b1a5/ext/openssl/openssl.c#L7333). Can you please provide a complete reproducer that demonstrates the issue? ------------------------------------------------------------------------ [2021-10-04 17:12:50] alec at alec dot pl Description: ------------ If I do: $tag = null; openssl_decrypt($cipher, $method, $ckey, $opts, $iv, $tag); I get: PHP Deprecated: openssl_decrypt(): Passing null to parameter #6 ($tag) of type string is deprecated. But if I do: $tag = ''; openssl_decrypt($cipher, $method, $ckey, $opts, $iv, $tag); I get: PHP Warning: openssl_decrypt(): The tag cannot be used because the cipher algorithm does not support AEAD. I understand the warnings, but this is not convenient if my code is supposed to support AEAD and non-AEAD cipher methods. Do I have to do two code paths depending on the cipher method is used? What's more. The default value for the $tag argument in openssl_encrypt() is null, which sounds kind of inconsistent. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=81502&edit=1