Re: [boost] Any interest in hashing algorithms SHA and/or FNV1a?

Subject: Re: [boost] Any interest in hashing algorithms SHA and/or FNV1a?
From: Jeff Flinn (Jeffrey.Flinn_at_[hidden])
Date: 2013-11-13 09:43:36

On 11/12/2013 1:52 PM, foster brereton wrote:
> I have been working on implementations of the SHA and FNV-1a class of
> hashing algorithms. Both are header-only.
>
> SHA (Secure Hash Algorithms)
> Implementations for SHA-1, -224, -256, -384, and -512. It does not
> implement the more recent SHA-3 (Keccak) algorithm. It would not be
> difficult to add support for 512/224 and 512/256 if they were desired.
> The routines support bit-level messages, meaning they can correctly
> digest messages that do not end on a byte boundary. More information
> here:
>      http://en.wikipedia.org/wiki/Secure_Hash_Algorithm
>
> FNV (Fowler–Noll–Vo)
> The header supports the FNV-1a algorithm, which has better
> distribution characteristics than its cousin, FNV-1. I have added
> support for 32-, 64-, 128-, 256-, and 1024-bit variants. This is not a
> cryptographically secure algorithm, however is much faster than its
> crypto cousins and as such is a solid algorithm for obtaining unique
> hash values for e.g., data structures. I have also implemented a
> constexpr variant of the algorithm (32-bit and 64-bit only) for const
> char* to further performance when needed by pushing the hash to
> compile-time computation.
> More information here:
>      http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
>
> The algorithms are currently part of the Adobe Source Libraries on GitHub:
>
> SHA:
> https://github.com/stlab/adobe_source_libraries/blob/sha_cleanup/adobe/sha.hpp
> (note: the master branch version needs updating to this one.)
>
> FNV-1a:
> https://github.com/stlab/adobe_source_libraries/blob/master/adobe/fnv.hpp
>
> Would these algorithms be of general use to the Boost community? If so
> I would be willing to submit them formally.

Have you seen:
https://github.com/boost-vault/Miscellaneous/blob/master/boost_crypto.zip
https://github.com/boost-vault/Miscellaneous/blob/master/crypto_v01.zip

I'll take a look at your ASL links today. Do you have any comparisons 
with openssl or libcryptocpp? I'm primarily interested in MD5 & SHA1 for 
legacy reasons. My understanding is that these algorithms are not 
parallelizable due to inherent data dependencies. In my situation I need 
both MD5 & SHA1 over the same sequence. I'd like to treat these as a 
composite hash. My thought is that this should allow the 
compiler/processor to better schedule instructions leading to better 
performance. That's my hypothesis anyway.

The other issue I have is that with the above mentioned api's each 
duplicate buffering of incoming data. So in my case I've got the disk, 
os, std::stream_buf, MD5 and SHA1 each doing buffering. Seems that these 
could be merged and there would be benefit to interleaving disk io with 
processing the composite hash on a 64 byte block basis. I know the 
number of incoming full blocks and would like to call the vault's 
crypto_v01 process_block functions for those and then call update with 
the remaining partial block.

So, bottom line - I'm interested.

Thanks, Jeff