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Date: Thu, 7 Jan 2016 10:54:51 -0500
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To: =?UTF-8?Q?Rouven_We=C3=9Fling?= <me@rouvenwessling.de>
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Subject: Re: [PHP-DEV] [RFC] Libsodium
From: scott@paragonie.com (Scott Arciszewski)

On Thu, Jan 7, 2016 at 10:52 AM, Rouven We=C3=9Fling <me@rouvenwessling.de>=
 wrote:
> Hi Scott,
>
> questions inline.
>
>> On 07 Jan 2016, at 14:26, Scott Arciszewski <scott@paragonie.com> wrote:
>>
>> I've updated the RFC to make libsodium a core PHP extension in 7.1, to
>> include references to the online documentation.
>>
>> https://wiki.php.net/rfc/libsodium
>
> I know this is made difficult by the fact that this is an existing, stabl=
e PECL extension, which also supports older PHP versions but I don=E2=80=99=
t think it=E2=80=99s a good idea to introduce more functions that duplicate=
 things handled already in core (I don=E2=80=99t mean in ext-openssl as lib=
 sodium would be an alternative to that extension). I=E2=80=99d rather see =
less duplication, not more.
>
> From a quick glance the following functions seems to be already covered:
> \Sodium\memcmp
> \Sodium\bin2hex
> \Sodium\hex2bin
> \Sodium\randombytes_buf
> \Sodium\randombytes_uniform
> \Sodium\randombytes_random16
>
> If their implementation is better than the core implementation, core shou=
ld be fixed.
>
> Do the hashing functions have any advantage over those provided by ext-ha=
sh?
>
> There are also a couple of other functions whose value I=E2=80=99d questi=
on, I=E2=80=99ll send an email about those later.
>
>> This is part of an overall effort to improve PHP's cryptography; up
>> next will be the pluggable crypto API that supports multiple backends
>> (with a scope limited to openssl and libsodium at the time of release)
>> but always provide conservative defaults.
>
> A more general question: I haven=E2=80=99t looked at your prototype for a=
 higher level API yet, but I=E2=80=99m wondering if it=E2=80=99s still nece=
ssary to introduce another low level API? When would I choose to use the la=
tter?
>
> Best regards
> Rouven

The high-level API ties the user's hands and doesn't give them direct
access to primitives. You can't use it for AES-256-ECB, you can only
use it for AES-256-CTR+HMAC-SHA-384, with an encoded and
version-tagged output, for example.

You still need ext/libsodium if you need to use any of its features
directly, such as \Sodium\memzero().

Scott Arciszewski
Chief Development Officer
Paragon Initiative Enterprises <https://paragonie.com>