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Subject: Re: [boost] Any interest in hashing algorithms SHA and/or FNV1a?
From: foster brereton (fosterb+boost_at_[hidden])
Date: 2013-11-14 13:54:31

On Thu, Nov 14, 2013 at 9:24 AM, Jeff Flinn <Jeffrey.Flinn_at_[hidden]> wrote:


> all the code but the call to perform_algorithm() deal with buffering, which
> ends up being redundant with the buffering typically provided by client
> code. The boost vault hash api exposes a process_block() method avoiding
> redundant buffering. This allows me to do something like:
> boost::crypto::md5 h;
> boost::for_each
> (block_range
> , [h&](const block& b){ h.process_block(b); other(b); });
> h.input(tail_data_ptr, tail_data_count);
> h.digest();


I see what you mean now about the double-buffering, and my hash code
is guilty of the same offense. I can look into modifying it to expose
the process_block routine, however...

I have been doing profiling of my SHA implementations, and copying the
data around doesn't even show up on the radar -- the vast majority of
the time, by far, is in the actual digest routine. The profile for MD5
may look different, but at least in the case of SHA I don't know how
much the straight-buffer-processing gains you.


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