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Date: Wed, 6 Jan 2016 19:59:50 +0000
Message-ID: <CAEKnhAGU=OEA54xRzZ4djtCGaQsndxpT5zXBenRFYisH654abA@mail.gmail.com>
To: Bishop Bettini <bishop@php.net>
Cc: PHP internals list <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11425fba041e350528afccf1
Subject: Re: [PHP-DEV] [RFC] OpenSSL AEAD support
From: bukka@php.net (Jakub Zelenka)

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Content-Type: text/plain; charset=UTF-8

On Wed, Jan 6, 2016 at 7:28 PM, Bishop Bettini <bishop@php.net> wrote:

> On Wed, Jan 6, 2016 at 11:09 AM, Jakub Zelenka <bukka@php.net> wrote:
>
>> Hi,
>>
>> On Wed, Jan 6, 2016 at 3:35 PM, Bishop Bettini <bishop@php.net> wrote:
>>
>>>
>>> I think the API might need to be more generic so that any future cipher
>>> modes with different parameters could also be passed in.
>>>
>>> Please see note in
>> https://wiki.php.net/rfc/openssl_aead#rejected_features . Any context
>> related features will add a lot to the size of the implementation. In this
>> case it would also mean introducing an object with dimension handler to the
>> openssl ext which doesn't really match with the rest of the extension API.
>> The proposed API is more conformant to the rest and the code addition is
>> also limited which is very important from the maintenance point of view.
>>
>
> Ok, a context resource may not be pragmatic. Perhaps a compromise in the
> form of a thin wrapper:
>
> string openssl_encrypt_aead(string $data , string $method , string
> $password [, int $options = 0 [, string $iv = "" [, string &$tag = "" [,
> string $aad = "" [, int $tag_length = 16 ]]]])
>
> string openssl_decrypt_aead(string $data , string $method , string
> $password [, int $options = 0 [, string $iv = "" [, string $tag = "" [,
> string $aad = "" ]]]] )
>
> This actually feels more right anyway: openssl_encrypt only does
> encryption, whereas openssl_encrypt_aead does encryption *and*
> integrity.  I would hate for users to pass a method of aes128 and think
> they can forgo an HMAC because they thought PHP would give them back a
> valid tag.
>

This is a good point. I would probably go with a bit different and maybe
simpler solution. How about emitting notice when $tag param is supplied for
non aead mode?

Thanks for the feedback!

Jakub

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