phc-discussions - Re: [PHC] Combining sliding window and bit-reversal

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAOLP8p5R50T-wZLhy62LmLi2NSA_2ocaysNx5mcF1wJdb_o=JA@mail.gmail.com>
Date: Mon, 27 Jan 2014 19:00:58 -0500
From: Bill Cox <waywardgeek@...il.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] Combining sliding window and bit-reversal

The Catena code does it this way:

- swap 4 bytes little-endian to big-endian style - 4 cycles max, or 1
in parallel.
- swap each upper nibble with the lower nibble:
    x = ((x & F0F0F0F0) >> 4) | ((x & 0x0F0F0F0F) << 4)
- swap bit pairs...

you get the idea.

It's just a few cycles.  Once per memory block, and it's no problem.

Bill