From 1ca1b917940c24ca3d1f490118c5474168622953 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 16 Nov 2018 17:26:21 -0800 Subject: crypto: chacha20-generic - refactor to allow varying number of rounds In preparation for adding XChaCha12 support, rename/refactor chacha20-generic to support different numbers of rounds. The justification for needing XChaCha12 support is explained in more detail in the patch "crypto: chacha - add XChaCha12 support". The only difference between ChaCha{8,12,20} are the number of rounds itself; all other parts of the algorithm are the same. Therefore, remove the "20" from all definitions, structures, functions, files, etc. that will be shared by all ChaCha versions. Also make ->setkey() store the round count in the chacha_ctx (previously chacha20_ctx). The generic code then passes the round count through to chacha_block(). There will be a ->setkey() function for each explicitly allowed round count; the encrypt/decrypt functions will be the same. I decided not to do it the opposite way (same ->setkey() function for all round counts, with different encrypt/decrypt functions) because that would have required more boilerplate code in architecture-specific implementations of ChaCha and XChaCha. Reviewed-by: Ard Biesheuvel Acked-by: Martin Willi Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- lib/Makefile | 2 +- lib/chacha.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ lib/chacha20.c | 112 ------------------------------------------------------ 3 files changed, 118 insertions(+), 113 deletions(-) create mode 100644 lib/chacha.c delete mode 100644 lib/chacha20.c (limited to 'lib') diff --git a/lib/Makefile b/lib/Makefile index db06d1237898..4c2b6fc5cde9 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -20,7 +20,7 @@ KCOV_INSTRUMENT_dynamic_debug.o := n lib-y := ctype.o string.o vsprintf.o cmdline.o \ rbtree.o radix-tree.o timerqueue.o xarray.o \ idr.o int_sqrt.o extable.o \ - sha1.o chacha20.o irq_regs.o argv_split.o \ + sha1.o chacha.o irq_regs.o argv_split.o \ flex_proportions.o ratelimit.o show_mem.o \ is_single_threaded.o plist.o decompress.o kobject_uevent.o \ earlycpio.o seq_buf.o siphash.o dec_and_lock.o \ diff --git a/lib/chacha.c b/lib/chacha.c new file mode 100644 index 000000000000..1bdc688c18df --- /dev/null +++ b/lib/chacha.c @@ -0,0 +1,117 @@ +/* + * The "hash function" used as the core of the ChaCha stream cipher (RFC7539) + * + * Copyright (C) 2015 Martin Willi + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ + +#include +#include +#include +#include +#include +#include + +static void chacha_permute(u32 *x, int nrounds) +{ + int i; + + /* whitelist the allowed round counts */ + WARN_ON_ONCE(nrounds != 20); + + for (i = 0; i < nrounds; 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); + x[2] += x[6]; x[14] = rol32(x[14] ^ x[2], 16); + x[3] += x[7]; x[15] = rol32(x[15] ^ x[3], 16); + + x[8] += x[12]; x[4] = rol32(x[4] ^ x[8], 12); + x[9] += x[13]; x[5] = rol32(x[5] ^ x[9], 12); + x[10] += x[14]; x[6] = rol32(x[6] ^ x[10], 12); + x[11] += x[15]; x[7] = rol32(x[7] ^ x[11], 12); + + x[0] += x[4]; x[12] = rol32(x[12] ^ x[0], 8); + x[1] += x[5]; x[13] = rol32(x[13] ^ x[1], 8); + x[2] += x[6]; x[14] = rol32(x[14] ^ x[2], 8); + x[3] += x[7]; x[15] = rol32(x[15] ^ x[3], 8); + + x[8] += x[12]; x[4] = rol32(x[4] ^ x[8], 7); + x[9] += x[13]; x[5] = rol32(x[5] ^ x[9], 7); + x[10] += x[14]; x[6] = rol32(x[6] ^ x[10], 7); + x[11] += x[15]; x[7] = rol32(x[7] ^ x[11], 7); + + x[0] += x[5]; x[15] = rol32(x[15] ^ x[0], 16); + x[1] += x[6]; x[12] = rol32(x[12] ^ x[1], 16); + x[2] += x[7]; x[13] = rol32(x[13] ^ x[2], 16); + x[3] += x[4]; x[14] = rol32(x[14] ^ x[3], 16); + + x[10] += x[15]; x[5] = rol32(x[5] ^ x[10], 12); + x[11] += x[12]; x[6] = rol32(x[6] ^ x[11], 12); + x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 12); + x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 12); + + x[0] += x[5]; x[15] = rol32(x[15] ^ x[0], 8); + x[1] += x[6]; x[12] = rol32(x[12] ^ x[1], 8); + x[2] += x[7]; x[13] = rol32(x[13] ^ x[2], 8); + x[3] += x[4]; x[14] = rol32(x[14] ^ x[3], 8); + + x[10] += x[15]; x[5] = rol32(x[5] ^ x[10], 7); + x[11] += x[12]; x[6] = rol32(x[6] ^ x[11], 7); + x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 7); + x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 7); + } +} + +/** + * chacha_block - generate one keystream block and increment block counter + * @state: input state matrix (16 32-bit words) + * @stream: output keystream block (64 bytes) + * @nrounds: number of rounds (currently must be 20) + * + * This is the ChaCha 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 chacha_block(u32 *state, u8 *stream, int nrounds) +{ + u32 x[16]; + int i; + + memcpy(x, state, 64); + + chacha_permute(x, nrounds); + + for (i = 0; i < ARRAY_SIZE(x); i++) + put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]); + + state[12]++; +} +EXPORT_SYMBOL(chacha_block); + +/** + * hchacha_block - abbreviated ChaCha core, for XChaCha + * @in: input state matrix (16 32-bit words) + * @out: output (8 32-bit words) + * @nrounds: number of rounds (currently must be 20) + * + * HChaCha is the ChaCha equivalent of HSalsa and is an intermediate step + * towards XChaCha (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf). HChaCha + * 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 hchacha_block(const u32 *in, u32 *out, int nrounds) +{ + u32 x[16]; + + memcpy(x, in, 64); + + chacha_permute(x, nrounds); + + memcpy(&out[0], &x[0], 16); + memcpy(&out[4], &x[12], 16); +} +EXPORT_SYMBOL(hchacha_block); diff --git a/lib/chacha20.c b/lib/chacha20.c deleted file mode 100644 index 6a484e16171d..000000000000 --- a/lib/chacha20.c +++ /dev/null @@ -1,112 +0,0 @@ -/* - * The "hash function" used as the core of the ChaCha20 stream cipher (RFC7539) - * - * Copyright (C) 2015 Martin Willi - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - */ - -#include -#include -#include -#include -#include -#include - -static void chacha20_permute(u32 *x) -{ - int 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); - x[2] += x[6]; x[14] = rol32(x[14] ^ x[2], 16); - x[3] += x[7]; x[15] = rol32(x[15] ^ x[3], 16); - - x[8] += x[12]; x[4] = rol32(x[4] ^ x[8], 12); - x[9] += x[13]; x[5] = rol32(x[5] ^ x[9], 12); - x[10] += x[14]; x[6] = rol32(x[6] ^ x[10], 12); - x[11] += x[15]; x[7] = rol32(x[7] ^ x[11], 12); - - x[0] += x[4]; x[12] = rol32(x[12] ^ x[0], 8); - x[1] += x[5]; x[13] = rol32(x[13] ^ x[1], 8); - x[2] += x[6]; x[14] = rol32(x[14] ^ x[2], 8); - x[3] += x[7]; x[15] = rol32(x[15] ^ x[3], 8); - - x[8] += x[12]; x[4] = rol32(x[4] ^ x[8], 7); - x[9] += x[13]; x[5] = rol32(x[5] ^ x[9], 7); - x[10] += x[14]; x[6] = rol32(x[6] ^ x[10], 7); - x[11] += x[15]; x[7] = rol32(x[7] ^ x[11], 7); - - x[0] += x[5]; x[15] = rol32(x[15] ^ x[0], 16); - x[1] += x[6]; x[12] = rol32(x[12] ^ x[1], 16); - x[2] += x[7]; x[13] = rol32(x[13] ^ x[2], 16); - x[3] += x[4]; x[14] = rol32(x[14] ^ x[3], 16); - - x[10] += x[15]; x[5] = rol32(x[5] ^ x[10], 12); - x[11] += x[12]; x[6] = rol32(x[6] ^ x[11], 12); - x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 12); - x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 12); - - x[0] += x[5]; x[15] = rol32(x[15] ^ x[0], 8); - x[1] += x[6]; x[12] = rol32(x[12] ^ x[1], 8); - x[2] += x[7]; x[13] = rol32(x[13] ^ x[2], 8); - x[3] += x[4]; x[14] = rol32(x[14] ^ x[3], 8); - - x[10] += x[15]; x[5] = rol32(x[5] ^ x[10], 7); - x[11] += x[12]; x[6] = rol32(x[6] ^ x[11], 7); - 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, u8 *stream) -{ - u32 x[16]; - int i; - - memcpy(x, state, 64); - - chacha20_permute(x); - - for (i = 0; i < ARRAY_SIZE(x); i++) - put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]); - - 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); -- cgit v1.2.3