From patchwork Tue Jan 11 22:05:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 12710810 X-Patchwork-Delegate: kuba@kernel.org 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BD9AC4332F for ; Tue, 11 Jan 2022 22:05:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345603AbiAKWFY (ORCPT ); Tue, 11 Jan 2022 17:05:24 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:51544 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345416AbiAKWFY (ORCPT ); Tue, 11 Jan 2022 17:05:24 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9B59460C2C; Tue, 11 Jan 2022 22:05:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 000ADC36AE3; Tue, 11 Jan 2022 22:05:21 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="feUSDu3s" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1641938720; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=81oB8eaidO+xLFqjuIq9tnsTP2xJoidbMjbRIz3Pr2s=; b=feUSDu3sH8AYyHEwh0jHNYYc79o0Pjfw1QFZV1/+tMYfKEWEbtcI5U5KbHjc8lofM5/4Gl w0rJAhS5MTQStCR9hu9gUtdnk7+6zPW+opadfDUbuujQ3KS9tBEbEHnpsMHz/hhpc4IIA+ CNdzN++CdfmQRETMC2DYLxtXbuGPy0I= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id bcf52eb2 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Tue, 11 Jan 2022 22:05:20 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-crypto@vger.kernel.org, netdev@vger.kernel.org, wireguard@lists.zx2c4.com, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, geert@linux-m68k.org, tytso@mit.edu, gregkh@linuxfoundation.org, jeanphilippe.aumasson@gmail.com, ardb@kernel.org Cc: "Jason A. Donenfeld" , Herbert Xu Subject: [PATCH crypto v3 1/2] lib/crypto: blake2s: move hmac construction into wireguard Date: Tue, 11 Jan 2022 23:05:05 +0100 Message-Id: <20220111220506.742067-2-Jason@zx2c4.com> In-Reply-To: <20220111220506.742067-1-Jason@zx2c4.com> References: <20220111181037.632969-1-Jason@zx2c4.com> <20220111220506.742067-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Basically nobody should use blake2s in an HMAC construction; it already has a keyed variant. But unfortunately for historical reasons, Noise, used by WireGuard, uses HKDF quite strictly, which means we have to use this. Because this really shouldn't be used by others, this commit moves it into wireguard's noise.c locally, so that kernels that aren't using WireGuard don't get this superfluous code baked in. On m68k systems, this shaves off ~314 bytes. Cc: Geert Uytterhoeven Cc: Herbert Xu Acked-by: Ard Biesheuvel Signed-off-by: Jason A. Donenfeld --- drivers/net/wireguard/noise.c | 45 ++++++++++++++++++++++++++++++----- include/crypto/blake2s.h | 3 --- lib/crypto/blake2s-selftest.c | 31 ------------------------ lib/crypto/blake2s.c | 37 ---------------------------- 4 files changed, 39 insertions(+), 77 deletions(-) diff --git a/drivers/net/wireguard/noise.c b/drivers/net/wireguard/noise.c index c0cfd9b36c0b..720952b92e78 100644 --- a/drivers/net/wireguard/noise.c +++ b/drivers/net/wireguard/noise.c @@ -302,6 +302,41 @@ void wg_noise_set_static_identity_private_key( static_identity->static_public, private_key); } +static void hmac(u8 *out, const u8 *in, const u8 *key, const size_t inlen, const size_t keylen) +{ + struct blake2s_state state; + u8 x_key[BLAKE2S_BLOCK_SIZE] __aligned(__alignof__(u32)) = { 0 }; + u8 i_hash[BLAKE2S_HASH_SIZE] __aligned(__alignof__(u32)); + int i; + + if (keylen > BLAKE2S_BLOCK_SIZE) { + blake2s_init(&state, BLAKE2S_HASH_SIZE); + blake2s_update(&state, key, keylen); + blake2s_final(&state, x_key); + } else + memcpy(x_key, key, keylen); + + for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i) + x_key[i] ^= 0x36; + + blake2s_init(&state, BLAKE2S_HASH_SIZE); + blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE); + blake2s_update(&state, in, inlen); + blake2s_final(&state, i_hash); + + for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i) + x_key[i] ^= 0x5c ^ 0x36; + + blake2s_init(&state, BLAKE2S_HASH_SIZE); + blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE); + blake2s_update(&state, i_hash, BLAKE2S_HASH_SIZE); + blake2s_final(&state, i_hash); + + memcpy(out, i_hash, BLAKE2S_HASH_SIZE); + memzero_explicit(x_key, BLAKE2S_BLOCK_SIZE); + memzero_explicit(i_hash, BLAKE2S_HASH_SIZE); +} + /* This is Hugo Krawczyk's HKDF: * - https://eprint.iacr.org/2010/264.pdf * - https://tools.ietf.org/html/rfc5869 @@ -322,14 +357,14 @@ static void kdf(u8 *first_dst, u8 *second_dst, u8 *third_dst, const u8 *data, ((third_len || third_dst) && (!second_len || !second_dst)))); /* Extract entropy from data into secret */ - blake2s256_hmac(secret, data, chaining_key, data_len, NOISE_HASH_LEN); + hmac(secret, data, chaining_key, data_len, NOISE_HASH_LEN); if (!first_dst || !first_len) goto out; /* Expand first key: key = secret, data = 0x1 */ output[0] = 1; - blake2s256_hmac(output, output, secret, 1, BLAKE2S_HASH_SIZE); + hmac(output, output, secret, 1, BLAKE2S_HASH_SIZE); memcpy(first_dst, output, first_len); if (!second_dst || !second_len) @@ -337,8 +372,7 @@ static void kdf(u8 *first_dst, u8 *second_dst, u8 *third_dst, const u8 *data, /* Expand second key: key = secret, data = first-key || 0x2 */ output[BLAKE2S_HASH_SIZE] = 2; - blake2s256_hmac(output, output, secret, BLAKE2S_HASH_SIZE + 1, - BLAKE2S_HASH_SIZE); + hmac(output, output, secret, BLAKE2S_HASH_SIZE + 1, BLAKE2S_HASH_SIZE); memcpy(second_dst, output, second_len); if (!third_dst || !third_len) @@ -346,8 +380,7 @@ static void kdf(u8 *first_dst, u8 *second_dst, u8 *third_dst, const u8 *data, /* Expand third key: key = secret, data = second-key || 0x3 */ output[BLAKE2S_HASH_SIZE] = 3; - blake2s256_hmac(output, output, secret, BLAKE2S_HASH_SIZE + 1, - BLAKE2S_HASH_SIZE); + hmac(output, output, secret, BLAKE2S_HASH_SIZE + 1, BLAKE2S_HASH_SIZE); memcpy(third_dst, output, third_len); out: diff --git a/include/crypto/blake2s.h b/include/crypto/blake2s.h index bc3fb59442ce..4e30e1799e61 100644 --- a/include/crypto/blake2s.h +++ b/include/crypto/blake2s.h @@ -101,7 +101,4 @@ static inline void blake2s(u8 *out, const u8 *in, const u8 *key, blake2s_final(&state, out); } -void blake2s256_hmac(u8 *out, const u8 *in, const u8 *key, const size_t inlen, - const size_t keylen); - #endif /* _CRYPTO_BLAKE2S_H */ diff --git a/lib/crypto/blake2s-selftest.c b/lib/crypto/blake2s-selftest.c index 5d9ea53be973..409e4b728770 100644 --- a/lib/crypto/blake2s-selftest.c +++ b/lib/crypto/blake2s-selftest.c @@ -15,7 +15,6 @@ * #include * * #include - * #include * * #define BLAKE2S_TESTVEC_COUNT 256 * @@ -58,16 +57,6 @@ * } * printf("};\n\n"); * - * printf("static const u8 blake2s_hmac_testvecs[][BLAKE2S_HASH_SIZE] __initconst = {\n"); - * - * HMAC(EVP_blake2s256(), key, sizeof(key), buf, sizeof(buf), hash, NULL); - * print_vec(hash, BLAKE2S_OUTBYTES); - * - * HMAC(EVP_blake2s256(), buf, sizeof(buf), key, sizeof(key), hash, NULL); - * print_vec(hash, BLAKE2S_OUTBYTES); - * - * printf("};\n"); - * * return 0; *} */ @@ -554,15 +543,6 @@ static const u8 blake2s_testvecs[][BLAKE2S_HASH_SIZE] __initconst = { 0xd6, 0x98, 0x6b, 0x07, 0x10, 0x65, 0x52, 0x65, }, }; -static const u8 blake2s_hmac_testvecs[][BLAKE2S_HASH_SIZE] __initconst = { - { 0xce, 0xe1, 0x57, 0x69, 0x82, 0xdc, 0xbf, 0x43, 0xad, 0x56, 0x4c, 0x70, - 0xed, 0x68, 0x16, 0x96, 0xcf, 0xa4, 0x73, 0xe8, 0xe8, 0xfc, 0x32, 0x79, - 0x08, 0x0a, 0x75, 0x82, 0xda, 0x3f, 0x05, 0x11, }, - { 0x77, 0x2f, 0x0c, 0x71, 0x41, 0xf4, 0x4b, 0x2b, 0xb3, 0xc6, 0xb6, 0xf9, - 0x60, 0xde, 0xe4, 0x52, 0x38, 0x66, 0xe8, 0xbf, 0x9b, 0x96, 0xc4, 0x9f, - 0x60, 0xd9, 0x24, 0x37, 0x99, 0xd6, 0xec, 0x31, }, -}; - bool __init blake2s_selftest(void) { u8 key[BLAKE2S_KEY_SIZE]; @@ -607,16 +587,5 @@ bool __init blake2s_selftest(void) } } - if (success) { - blake2s256_hmac(hash, buf, key, sizeof(buf), sizeof(key)); - success &= !memcmp(hash, blake2s_hmac_testvecs[0], BLAKE2S_HASH_SIZE); - - blake2s256_hmac(hash, key, buf, sizeof(key), sizeof(buf)); - success &= !memcmp(hash, blake2s_hmac_testvecs[1], BLAKE2S_HASH_SIZE); - - if (!success) - pr_err("blake2s256_hmac self-test: FAIL\n"); - } - return success; } diff --git a/lib/crypto/blake2s.c b/lib/crypto/blake2s.c index 93f2ae051370..9364f79937b8 100644 --- a/lib/crypto/blake2s.c +++ b/lib/crypto/blake2s.c @@ -30,43 +30,6 @@ void blake2s_final(struct blake2s_state *state, u8 *out) } EXPORT_SYMBOL(blake2s_final); -void blake2s256_hmac(u8 *out, const u8 *in, const u8 *key, const size_t inlen, - const size_t keylen) -{ - struct blake2s_state state; - u8 x_key[BLAKE2S_BLOCK_SIZE] __aligned(__alignof__(u32)) = { 0 }; - u8 i_hash[BLAKE2S_HASH_SIZE] __aligned(__alignof__(u32)); - int i; - - if (keylen > BLAKE2S_BLOCK_SIZE) { - blake2s_init(&state, BLAKE2S_HASH_SIZE); - blake2s_update(&state, key, keylen); - blake2s_final(&state, x_key); - } else - memcpy(x_key, key, keylen); - - for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i) - x_key[i] ^= 0x36; - - blake2s_init(&state, BLAKE2S_HASH_SIZE); - blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE); - blake2s_update(&state, in, inlen); - blake2s_final(&state, i_hash); - - for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i) - x_key[i] ^= 0x5c ^ 0x36; - - blake2s_init(&state, BLAKE2S_HASH_SIZE); - blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE); - blake2s_update(&state, i_hash, BLAKE2S_HASH_SIZE); - blake2s_final(&state, i_hash); - - memcpy(out, i_hash, BLAKE2S_HASH_SIZE); - memzero_explicit(x_key, BLAKE2S_BLOCK_SIZE); - memzero_explicit(i_hash, BLAKE2S_HASH_SIZE); -} -EXPORT_SYMBOL(blake2s256_hmac); - static int __init blake2s_mod_init(void) { if (!IS_ENABLED(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS) && From patchwork Tue Jan 11 22:05:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 12710811 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84B66C433EF for ; Tue, 11 Jan 2022 22:05:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345772AbiAKWFe (ORCPT ); Tue, 11 Jan 2022 17:05:34 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:42248 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345691AbiAKWFa (ORCPT ); Tue, 11 Jan 2022 17:05:30 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 8DFE5B81D64; Tue, 11 Jan 2022 22:05:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DED5C36AE9; Tue, 11 Jan 2022 22:05:26 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="S3NV3SjU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1641938725; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=O7t1K3lQeoHUm9AoU+DjJ3MCcxGxvVz/RPJNEpctrWA=; b=S3NV3SjUFiN9tMOjkT1zoy8sfMRJNBFcV7UX6nD1n4dBZ6JO9xrDB82HjlgbG84K3Q7Vu8 u1RMXjKSjc4lgKUNskhy8E6MWZx6l0ilzO5qQRGAJY7msoRVTlL/WFp6h8efFGTc+Mim1W B8XGg830wMmjQvLWdeKXCAHSBjsZFX8= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id f9b0db15 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Tue, 11 Jan 2022 22:05:25 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-crypto@vger.kernel.org, netdev@vger.kernel.org, wireguard@lists.zx2c4.com, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, geert@linux-m68k.org, tytso@mit.edu, gregkh@linuxfoundation.org, jeanphilippe.aumasson@gmail.com, ardb@kernel.org Cc: "Jason A. Donenfeld" , Herbert Xu Subject: [PATCH crypto v3 2/2] lib/crypto: sha1: re-roll loops to reduce code size Date: Tue, 11 Jan 2022 23:05:06 +0100 Message-Id: <20220111220506.742067-3-Jason@zx2c4.com> In-Reply-To: <20220111220506.742067-1-Jason@zx2c4.com> References: <20220111181037.632969-1-Jason@zx2c4.com> <20220111220506.742067-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org With SHA-1 no longer being used for anything performance oriented, and also soon to be phased out entirely, we can make up for the space added by unrolled BLAKE2s by simply re-rolling SHA-1. Since SHA-1 is so much more complex, re-rolling it more or less takes care of the code size added by BLAKE2s. And eventually, hopefully we'll see SHA-1 removed entirely from most small kernel builds. Cc: Geert Uytterhoeven Cc: Herbert Xu Cc: Ard Biesheuvel Signed-off-by: Jason A. Donenfeld --- lib/sha1.c | 95 ++++++++---------------------------------------------- 1 file changed, 14 insertions(+), 81 deletions(-) diff --git a/lib/sha1.c b/lib/sha1.c index 9bd1935a1472..0494766fc574 100644 --- a/lib/sha1.c +++ b/lib/sha1.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include @@ -55,7 +56,8 @@ #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \ __u32 TEMP = input(t); setW(t, TEMP); \ E += TEMP + rol32(A,5) + (fn) + (constant); \ - B = ror32(B, 2); } while (0) + B = ror32(B, 2); \ + TEMP = E; E = D; D = C; C = B; B = A; A = TEMP; } while (0) #define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E ) #define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E ) @@ -84,6 +86,7 @@ void sha1_transform(__u32 *digest, const char *data, __u32 *array) { __u32 A, B, C, D, E; + unsigned int i = 0; A = digest[0]; B = digest[1]; @@ -92,94 +95,24 @@ void sha1_transform(__u32 *digest, const char *data, __u32 *array) E = digest[4]; /* Round 1 - iterations 0-16 take their input from 'data' */ - T_0_15( 0, A, B, C, D, E); - T_0_15( 1, E, A, B, C, D); - T_0_15( 2, D, E, A, B, C); - T_0_15( 3, C, D, E, A, B); - T_0_15( 4, B, C, D, E, A); - T_0_15( 5, A, B, C, D, E); - T_0_15( 6, E, A, B, C, D); - T_0_15( 7, D, E, A, B, C); - T_0_15( 8, C, D, E, A, B); - T_0_15( 9, B, C, D, E, A); - T_0_15(10, A, B, C, D, E); - T_0_15(11, E, A, B, C, D); - T_0_15(12, D, E, A, B, C); - T_0_15(13, C, D, E, A, B); - T_0_15(14, B, C, D, E, A); - T_0_15(15, A, B, C, D, E); + for (; i < 16; ++i) + T_0_15(i, A, B, C, D, E); /* Round 1 - tail. Input from 512-bit mixing array */ - T_16_19(16, E, A, B, C, D); - T_16_19(17, D, E, A, B, C); - T_16_19(18, C, D, E, A, B); - T_16_19(19, B, C, D, E, A); + for (; i < 20; ++i) + T_16_19(i, A, B, C, D, E); /* Round 2 */ - T_20_39(20, A, B, C, D, E); - T_20_39(21, E, A, B, C, D); - T_20_39(22, D, E, A, B, C); - T_20_39(23, C, D, E, A, B); - T_20_39(24, B, C, D, E, A); - T_20_39(25, A, B, C, D, E); - T_20_39(26, E, A, B, C, D); - T_20_39(27, D, E, A, B, C); - T_20_39(28, C, D, E, A, B); - T_20_39(29, B, C, D, E, A); - T_20_39(30, A, B, C, D, E); - T_20_39(31, E, A, B, C, D); - T_20_39(32, D, E, A, B, C); - T_20_39(33, C, D, E, A, B); - T_20_39(34, B, C, D, E, A); - T_20_39(35, A, B, C, D, E); - T_20_39(36, E, A, B, C, D); - T_20_39(37, D, E, A, B, C); - T_20_39(38, C, D, E, A, B); - T_20_39(39, B, C, D, E, A); + for (; i < 40; ++i) + T_20_39(i, A, B, C, D, E); /* Round 3 */ - T_40_59(40, A, B, C, D, E); - T_40_59(41, E, A, B, C, D); - T_40_59(42, D, E, A, B, C); - T_40_59(43, C, D, E, A, B); - T_40_59(44, B, C, D, E, A); - T_40_59(45, A, B, C, D, E); - T_40_59(46, E, A, B, C, D); - T_40_59(47, D, E, A, B, C); - T_40_59(48, C, D, E, A, B); - T_40_59(49, B, C, D, E, A); - T_40_59(50, A, B, C, D, E); - T_40_59(51, E, A, B, C, D); - T_40_59(52, D, E, A, B, C); - T_40_59(53, C, D, E, A, B); - T_40_59(54, B, C, D, E, A); - T_40_59(55, A, B, C, D, E); - T_40_59(56, E, A, B, C, D); - T_40_59(57, D, E, A, B, C); - T_40_59(58, C, D, E, A, B); - T_40_59(59, B, C, D, E, A); + for (; i < 60; ++i) + T_40_59(i, A, B, C, D, E); /* Round 4 */ - T_60_79(60, A, B, C, D, E); - T_60_79(61, E, A, B, C, D); - T_60_79(62, D, E, A, B, C); - T_60_79(63, C, D, E, A, B); - T_60_79(64, B, C, D, E, A); - T_60_79(65, A, B, C, D, E); - T_60_79(66, E, A, B, C, D); - T_60_79(67, D, E, A, B, C); - T_60_79(68, C, D, E, A, B); - T_60_79(69, B, C, D, E, A); - T_60_79(70, A, B, C, D, E); - T_60_79(71, E, A, B, C, D); - T_60_79(72, D, E, A, B, C); - T_60_79(73, C, D, E, A, B); - T_60_79(74, B, C, D, E, A); - T_60_79(75, A, B, C, D, E); - T_60_79(76, E, A, B, C, D); - T_60_79(77, D, E, A, B, C); - T_60_79(78, C, D, E, A, B); - T_60_79(79, B, C, D, E, A); + for (; i < 80; ++i) + T_60_79(i, A, B, C, D, E); digest[0] += A; digest[1] += B;