From: "Allyn, Mark A" <mark.a.allyn@intel.com>
Subject: Questions about ahash
Date: Fri, 22 Oct 2010 10:54:58 -0600
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Folks:

I am attempting to implement an ahash instance for a hardware crypto device.

I see that there is a sha1 generic in the soruces a crypto/sha1_generic.c which uses the shash interface. I was hoping to use that, but there is some stuff in the headers that is confusing.

In include/crypto/hash.h, there is a structure crypto_ahash which has pointers to the init, update, final, etc algorithms. These same algorithms are also referred to in the ahash_alg structure.

In the case of shash, the crypto_shash structure does not have pointers to the algorithms.

Why is the crypto_ahash structure so different? 

There is a function shash_desc_ctx, but there is no function ahash_des_ctx. In the crys_sha1_init() function of sha1_generic, you call shash_desc_ctx. If I want to use the ahash instead of shash for sha1, then do I use shash_desc_ctx, or do I have to come up with my own ahash_desc_ctx?

Thanks

Mark Allyn