From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D32B4FF8868 for ; Tue, 28 Apr 2026 16:30:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:Subject:References:In-Reply-To:Message-Id:Cc:To:From:Date: MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zfgcXIInCPQxg83Ely+lCYsyKSEsGZlard+xYL4BOww=; b=LZJg+dD/nVakLiSv0P++bQC/4c d1DxxMosMC/xmoaSG7kZC5IDsSlwFbBZ0H7K2D8Clb7Amzpaez2pZFtP8nztTa3/xvjd2IZuzt4Dt 3lfsi+FvO7x92xUUH1Kjym4XZ/CtJElbaJR4yfxqbhekJpN1zEDP7O60TGQhNPHH4+Yy7gwLNPaEN vDa947F8HSTXh7BwvL7PyxtB1uF8qPAb70wk0gdmmrQINmqcVrwhy5AJP7jmfFSvQN5Nswl9g+UJI 8uOmVY6bxYLRnf9B5wovwda3Vpcj7E87PKlR3KrFo0u7DSA6MP9TDlUy+XentTtJL/PvVz2pQojAN TG4obVJg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wHlKQ-00000001wiF-1Q7B; Tue, 28 Apr 2026 16:30:30 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wHlKO-00000001whL-0UiN for linux-arm-kernel@lists.infradead.org; Tue, 28 Apr 2026 16:30:29 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 8012043F5B; Tue, 28 Apr 2026 16:30:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E56B1C4AF09; 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 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260428_093028_209103_3D4A9C83 X-CRM114-Status: GOOD ( 13.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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.