From patchwork Mon Aug 6 22:32:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10558065 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 316C51390 for ; Mon, 6 Aug 2018 22:35:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 20A7F29570 for ; Mon, 6 Aug 2018 22:35:57 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 14779297CE; Mon, 6 Aug 2018 22:35:57 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ABF5D29570 for ; Mon, 6 Aug 2018 22:35:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731938AbeHGAqM (ORCPT ); Mon, 6 Aug 2018 20:46:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:45080 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730888AbeHGAqL (ORCPT ); Mon, 6 Aug 2018 20:46:11 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D7CA221A60; Mon, 6 Aug 2018 22:34:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1533594898; bh=ptypddly68/mtHqA6v40Ih3M31L4+1CcEXAXZZcxVnE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UXT719cCSAbwUGAv0lSoPy+Q8J5cK9Ab77ULuzcu0O24m96cXC9ROZOt4v/h8cSqo OiWRc35V+Zvv2utpKlL/DRs9kbgkr1us0pIu0s8Wm/CABahqUdo7HPB/hJ9OQxgfkS GMsWwiFIXGgSooEqhkcC3MHRTHHTXTAOuFuBiqQk= From: Eric Biggers To: linux-crypto@vger.kernel.org Cc: linux-fscrypt@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Herbert Xu , Paul Crowley , Greg Kaiser , Michael Halcrow , "Jason A . Donenfeld" , Samuel Neves , Tomer Ashur , Eric Biggers Subject: [RFC PATCH 1/9] crypto: chacha20-generic - add HChaCha20 library function Date: Mon, 6 Aug 2018 15:32:52 -0700 Message-Id: <20180806223300.113891-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.18.0.597.ga71716f1ad-goog In-Reply-To: <20180806223300.113891-1-ebiggers@kernel.org> References: <20180806223300.113891-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Refactor the unkeyed permutation part of chacha20_block() into its own function, then add hchacha20_block() which is the ChaCha equivalent of HSalsa20 and is an intermediate step towards XChaCha20 (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf). HChaCha20 skips the final addition of the initial state, and outputs only certain words of the state. It should not be used for streaming directly. Signed-off-by: Eric Biggers --- include/crypto/chacha20.h | 2 ++ lib/chacha20.c | 52 +++++++++++++++++++++++++++++++++------ 2 files changed, 47 insertions(+), 7 deletions(-) diff --git a/include/crypto/chacha20.h b/include/crypto/chacha20.h index b83d66073db0..f00052137942 100644 --- a/include/crypto/chacha20.h +++ b/include/crypto/chacha20.h @@ -20,6 +20,8 @@ struct chacha20_ctx { }; void chacha20_block(u32 *state, u32 *stream); +void hchacha20_block(const u32 *in, u32 *out); + void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv); int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key, unsigned int keysize); diff --git a/lib/chacha20.c b/lib/chacha20.c index c1cc50fb68c9..13a0bdcb1604 100644 --- a/lib/chacha20.c +++ b/lib/chacha20.c @@ -1,5 +1,5 @@ /* - * ChaCha20 256-bit cipher algorithm, RFC7539 + * The "hash function" used as the core of the ChaCha20 stream cipher (RFC7539) * * Copyright (C) 2015 Martin Willi * @@ -16,14 +16,10 @@ #include #include -void chacha20_block(u32 *state, u32 *stream) +static void chacha20_permute(u32 *x) { - u32 x[16], *out = stream; int i; - for (i = 0; i < ARRAY_SIZE(x); i++) - x[i] = state[i]; - for (i = 0; i < 20; i += 2) { x[0] += x[4]; x[12] = rol32(x[12] ^ x[0], 16); x[1] += x[5]; x[13] = rol32(x[13] ^ x[1], 16); @@ -65,10 +61,52 @@ void chacha20_block(u32 *state, u32 *stream) x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 7); x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 7); } +} + +/** + * chacha20_block - generate one keystream block and increment block counter + * @state: input state matrix (16 32-bit words) + * @stream: output keystream block (64 bytes) + * + * This is the ChaCha20 core, a function from 64-byte strings to 64-byte + * strings. The caller has already converted the endianness of the input. This + * function also handles incrementing the block counter in the input matrix. + */ +void chacha20_block(u32 *state, u32 *stream) +{ + u32 x[16]; + int i; + + memcpy(x, state, 64); + + chacha20_permute(x); for (i = 0; i < ARRAY_SIZE(x); i++) - out[i] = cpu_to_le32(x[i] + state[i]); + stream[i] = cpu_to_le32(x[i] + state[i]); state[12]++; } EXPORT_SYMBOL(chacha20_block); + +/** + * hchacha20_block - abbreviated ChaCha20 core, for XChaCha20 + * @in: input state matrix (16 32-bit words) + * @out: output (8 32-bit words) + * + * HChaCha20 is the ChaCha equivalent of HSalsa20 and is an intermediate step + * towards XChaCha20 (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf). + * HChaCha20 skips the final addition of the initial state, and outputs only + * certain words of the state. It should not be used for streaming directly. + */ +void hchacha20_block(const u32 *in, u32 *out) +{ + u32 x[16]; + + memcpy(x, in, 64); + + chacha20_permute(x); + + memcpy(&out[0], &x[0], 16); + memcpy(&out[4], &x[12], 16); +} +EXPORT_SYMBOL(hchacha20_block);