Req #67304 [Asn]: openssl_decrypt fails with GCM mode

Edit report at https://bugs.php.net/bug.php?id=67304&edit=1 ID: 67304 Updated by: bukka@php.net Reported by: birki456 at hotmail dot com Summary: openssl_decrypt fails with GCM mode Status: Assigned Type: Feature/Change Request Package: OpenSSL related Operating System: all PHP Version: 5.5.12 Assigned To: bukka Block user comment: N Private report: N New Comment: This patch is just for master which means possibly next minor (7.1). Of course, if there are any objections against it, then I will have to write RFC and it will have to pass to get in... In any case I don't plan any back-port as the patch is relatively big for minor release considering that this is not a bug but more a feature request. If you need to use GCM in 5, you should take a look on my ext called crypto which already has full support for GCM and CCM: https://github.com/bukka/php-crypto Previous Comments: ------------------------------------------------------------------------ [2015-12-04 18:57:23] lagrange dot louis at gmail dot com Good news, thanks @bukka! Do you know in which branches this will be merged? (hopefully a 5.x branch) ------------------------------------------------------------------------ [2015-12-03 23:25:07] bukka@php.net I have been slowly working on it and should be hopefuly ready for 7.1: The progress can be seen here: https://github.com/php/php-src/compare/master...bukka:openssl_aead ------------------------------------------------------------------------ [2015-11-16 13:38:29] albertcasademont at gmail dot com This would be indeed very useful. Right now we have to do it in 2 steps with an hmac ------------------------------------------------------------------------ [2014-05-19 17:00:18] birki456 at hotmail dot com Description: ------------ While the gcm mode (which is authenticated encryption) is reported in openssl_get_cipher_methods() (e.g. [106] => aes-256-gcm), neither openssl_encrypt nor openssl_decrypt support it. There simply is no code to supply/return the authentication tag. It should be fairly simple to add however it possibly requires a change of the return type, because ciphertext and tag need to be returned in the encryption case and ciphertext and tag need to be supplied for decryption. It should also be possible to distinguish between decryption failure due to authentication failure vs. other failure. The code below *should*, as last line, print 'recovered: Hello World', however decryption with gcm always fails. Test script: --------------- echo print_r(openssl_get_cipher_methods(), true); $cipher = 'aes-256-gcm'; $ivlen = openssl_cipher_iv_length($cipher); echo "iv len: " . $ivlen . "\n"; $iv = openssl_random_pseudo_bytes($ivlen); $hexiv = bin2hex($iv); echo "iv: " . $hexiv . "\n"; $plaintext = "Hello World"; echo "plaintext: " . $plaintext . "\n"; $clearpass = 'passphrase'; $pbkdfsalt = openssl_random_pseudo_bytes(16); $password = hash_pbkdf2('sha256', $clearpass, $pbkdfsalt, 1001, 32, true); echo "clearpass: " . $clearpass . "\n"; echo "pbkdfsalt: " . bin2hex($pbkdfsalt) . "\n"; echo "password: " . bin2hex($password) . "\n"; // This is the important part: $ciphertext = openssl_encrypt($plaintext, $cipher, $password, 0, $iv); echo "ciphertext: " . print_r($ciphertext, true) . "\n"; $recovered = openssl_decrypt($ciphertext, $cipher, $password, 0, $iv); echo "recovered: " . $recovered . "\n"; ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=67304&edit=1