Re: [PATCH] AES x86-64-asm impl.
From: dean gaudet
Date: Sun Oct 03 2004 - 21:16:47 EST
On Sat, 2 Oct 2004, Andi Kleen wrote:
Unfortunately it's still fundamentally 32bit. Anybody interested
in doing a true 64bit AES?
i doubt it helps any -- except for benchmark-only purposes.
there's a description of the 32-bit T-table approach in section 7.3 of
basically the tables are 8-bit -> 32-bit maps, and there are 4 of them (2
for each direction). to go to 64-bit you'd need 16-bit -> 64-bit maps...
512KiB per table. there are some other variations on the tables which are
smaller, but nothing as small as the 1024 bytes per table of the 32-bit
there's a completely different approach using bit-slicing (basically
consider each register as 64 1-bit registers), which yields great
throughput but cruddy latency -- you basically need lots of non-dependant
streams to make this pay off (i.e. it might work for disk crypto
processing multiple blocks simultaneously).
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