From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A2DE12F549C; Tue, 28 Apr 2026 16:30:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777393827; cv=none; b=cJTfXKj2LwczRA//PW+7Rco0awYT3iU1/cUGG7QLUH7UHPOibyfs9XxE7KJmHqjFOX4ku9aKaLKcaUbWVZOcDm1uyW7Sf9Z5O8ekuOPE/zpBsLcwdcG8DzGxLy+XmwWwpmOy0d4e3Eg07JLhEN7BLy3e1Na0NRbCRDJUuzKtecU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777393827; c=relaxed/simple; bh=cT6jmt4+OY628kY0x9v/6nF8hRaDQ4Au465ssIAxw3M=; h=MIME-Version:Date:From:To:Cc:Message-Id:In-Reply-To:References: Subject:Content-Type; b=OJvcSzqSFAs5e/emuy+6bxlQn5DUnJnNmaBEerrRL4sAmBvKUx96wd36WOic5DIeDo9AnkLLLTCB9G7/UgMyBAtLVpzH1qlSKePq+FFate8/QJELs9HoIxCUs2fsp0jA+3hBsDkmHotPxb3uCahbPeMDp6VTDAep/QSeUv5yN9s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=F3y9O+aE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="F3y9O+aE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3434C2BCB5; Tue, 28 Apr 2026 16:30:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777393827; bh=cT6jmt4+OY628kY0x9v/6nF8hRaDQ4Au465ssIAxw3M=; h=Date:From:To:Cc:In-Reply-To:References:Subject:From; b=F3y9O+aEV2liAUh8duVwf15f7eF2F7pQp7XgzYRYG96dv2YDyXrG1XjtmGJT8NxKj ljx/29VNG6peiMYMKakDMz56w06QEZx3SSD6eR9/solDSIE88YU1nTAvu6QCK/JOeu 6G0pGEi+dj9KwqClqwldkEPa5sXfeEMqeRAenqw6s2HXZGV81kyBnuIR+myppq1ygA 8Xhv4zYF61zqC1rUiwriPLlwVNBz6aGT4hHW16pxiqzX3M5Hb6BDewTOC31xp9rp8V WX/hsyovH//iLhPL0puhEK0cYKCRy60F70fL1Q6ZOi8tCzE3KUyTA99PQpusOIsHzt F9toxrhrm+LfQ== Received: from phl-compute-01.internal (phl-compute-01.internal [10.202.2.41]) by mailfauth.phl.internal (Postfix) with ESMTP id F2CB6F4007A; Tue, 28 Apr 2026 12:30:25 -0400 (EDT) Received: from phl-imap-02 ([10.202.2.81]) by phl-compute-01.internal (MEProxy); Tue, 28 Apr 2026 12:30:26 -0400 X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefhedrtddtgdekvddtgecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpuffrtefokffrpgfnqfghnecuuegr ihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjug hrpefoggffhffvvefkjghfufgtgfesthhqredtredtjeenucfhrhhomhepfdetrhguuceu ihgvshhhvghuvhgvlhdfuceorghruggssehkvghrnhgvlhdrohhrgheqnecuggftrfgrth htvghrnhepueetieduieegkeejvdehudeiheettefgtdeugffhjefghfeftdelhedvheff hfdvnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomheprg hrugdomhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqudeijedthedttdejledq feefvdduieegudehqdgrrhgusgeppehkvghrnhgvlhdrohhrghesfihorhhkohhfrghrug drtghomhdpnhgspghrtghpthhtohepudefpdhmohguvgepshhmthhpohhuthdprhgtphht thhopegrlhgvgigrnhgurhgvrdgsvghllhhonhhisegsohhothhlihhnrdgtohhmpdhrtg hpthhtohepuggrvhgvmhesuggrvhgvmhhlohhfthdrnhgvthdprhgtphhtthhopeifrgih figrrhgughgvvghksehgmhgrihhlrdgtohhmpdhrtghpthhtohephhgvrhgsvghrthesgh honhguohhrrdgrphgrnhgrrdhorhhgrdgruhdprhgtphhtthhopehkrggsvghlsehkvghr nhgvlhdrohhrghdprhgtphhtthhopehlihhnuhhsfieskhgvrhhnvghlrdhorhhgpdhrtg hpthhtohepthhhohhrshhtvghnrdgslhhumheslhhinhhugidruggvvhdprhgtphhtthho pehlihhnuhigqdgrrhhmqdhkvghrnhgvlheslhhishhtshdrihhnfhhrrgguvggrugdroh hrghdprhgtphhtthhopehnihgtohhlrghsrdhfvghrrhgvsehmihgtrhhotghhihhprdgt ohhm X-ME-Proxy: Feedback-ID: ice86485a:Fastmail Received: by mailuser.phl.internal (Postfix, from userid 501) id D56D4700065; Tue, 28 Apr 2026 12:30:25 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Tue, 28 Apr 2026 18:30:05 +0200 From: "Ard Biesheuvel" To: =?UTF-8?Q?Marek_Beh=C3=BAn?= , "Thorsten Blum" Cc: "Bill Cox" , "Herbert Xu" , "David S. Miller" , "Nicolas Ferre" , "Alexandre Belloni" , "Claudiu Beznea" , "Linus Walleij" , stable@vger.kernel.org, linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Message-Id: In-Reply-To: References: <20260428101430.514838-3-thorsten.blum@linux.dev> <25ntssyy6t5uwxlwfpmrpzpcq6xv62l643hflf26hxi6lv5wqu@6vub6ysczjvd> Subject: Re: [PATCH v2] crypto: atmel-sha204a - drop hwrng quality reduction for ATSHA204A Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Tue, 28 Apr 2026, at 15:24, Marek Beh=C3=BAn wrote: > Hi Thorsten, > > Bill also wrote about ATSHA204A [1] > > My best guess as to what's going on here is that the device has a > ring-oscillator based entropy source, but that it generates only a f= ew bits > of entropy for each use. It seems to be called before generating ea= ch > 32-byte "random" value, which is why the second set of 32-bit values= have > more possible values, and the 3rd has even more. However, the numbe= r of > unique values in the final column of 32*N byte values is always equa= l to > the number of unique values of the entire string of bytes. > > If this is true that the device generates <256 true random bits and th= en > mixes in non-volatile pseudorandom number generator to produce 256 bit= s, > then the quality should not be set to full 1024. > This post is about the Hashlet, which has a ATSHA204 not ATSHA204A.