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From:   Stephan Mueller <smueller@chronox.de>
To:     Mohan Marutirao Dhanawade <mohand@xilinx.com>
Cc:     "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>
Subject: Re: Hardware TRNG driver framework selection criteria
Date:   Tue, 31 Dec 2019 13:47:45 +0100
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Am Montag, 30. Dezember 2019, 09:40:30 CET schrieb Mohan Marutirao Dhanawade:

Hi Mohan,

> Hi everyone,
> 
> I am writing Linux driver to support TRNG hardware module for Xilinx SoC. I
> am seeing two frameworks - crypto framework and hw_random (char driver)
> which can be used to write driver for TRNG. Can someone please educate me
> on what criteria is to be used to decide which framework to use for TRNG
> (Crypto framework / hw_random char driver)?

The crypto API RNG framework is used to implement deterministic RNGs which in 
turn need seending from a noise source.

The HW RNG framework is used for accessing RNGs which have their own noise 
source and provide random data with appropriate entropy. These RNGs are 
available via /dev/hwrng.
> 
> Regards,
> Mohan
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Ciao
Stephan