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From: Stephan Mueller <>
To: David Gstir <>
Cc: Linux Crypto Mailing List <>,, Richard Weinberger <>
Subject: Re: Can an ahash driver be used through shash API?
Date: Wed, 29 May 2019 16:18:18 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Am Mittwoch, 29. Mai 2019, 16:04:47 CEST schrieb David Gstir:

Hi David,

> Hi!
> I've done some testing with hardware acceleration of hash functions
> and noticed that, when using the synchronous message digest API (shash),
> some drivers are not usable. In my case the CAAM driver for SHA256.
> Using the asynchronous interface (ahash), everything works as expected.
> Looking at the driver source, the CAAM driver only implements the ahash
> interface.
> I'm wondering if there a way to use an ahash driver through the shash
> interface?

Short: no.
> I've seen that it does actually work the other way around, since
> crypto_init_shash_ops_async() in crypto/shash.c takes care of translating
> calls from ahash to shash and that's how the *-generic drivers are usable
> through the ahash API.

The crypto_alloc_shash will only identify cipher implementations that were 
registered with the CRYPTO_ALG_TYPE_SHASH flag. That flag is set when a cipher 
is registered using crypto_register_shash.

Thus, ciphers registered with crypto_register_ahash will not bear this flag 
and thus will not be found by the allocation function.


  reply	other threads:[~2019-05-29 14:24 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-29 14:04 David Gstir
2019-05-29 14:18 ` Stephan Mueller [this message]
2019-05-29 20:21   ` Richard Weinberger
2019-05-30  5:38     ` Stephan Mueller
2019-05-30 10:02     ` Pascal Van Leeuwen

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