From: Rodel Miguel <rodelfmiguel@gmail.com>
Subject: CRYPTO_ALG_TYPE_ABLKCIPHER concepts guide
Date: Mon, 14 May 2012 12:46:52 +0800
Message-ID: <CAPihpKCBxW6kFF9ZZLB9Y7P-EqbTEo_bnbPoCOZB16dxUT1APA@mail.gmail.com>
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To: linux-crypto@vger.kernel.org
Sender: linux-crypto-owner@vger.kernel.org

Hello Experts,

I am writing a driver for my AES encryption hardware.  It is a
hardware which can do encryption of 4k bytes of data every time.  I
have tried creating a driver based on geode-aes.c code which uses the
CRYPTO_ALG_TYPE_BLKCIPHER interface.  While testing the driver, I
found out that the limit for this type of API is 512 bytes of data
sent on every encryption/decryption call.  I have sent the dm-crypt
mailing list a query about this and they said that this limit cannot
be changed at the moment.

I am now looking at a different type of crypto API which is the
CRYPTO_ALG_TYPE_ABLKCIPHER but I could not find any
tutorials/documentation which would guide to the minimum code required
to create this type of driver.  I looked at the mv_cesa.c but I am
still quite lost at the procedures in doing this type of driver.  The
reason I want to explore this driver is that I am assuming that the
CRYPTO_ALG_TYPE_ABLKCIPHER type of interface would allow me to collect
4k bytes of data first before doing DMA to my hardware for
encryption/decryption.  Is this a correct assumption?

Is there a good documentation that would lay out the requirements to
write an asynchronous type of block cipher?

Thank you very much for your help!

Kind Regards,
Rodel