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author | Eric Biggers <ebiggers@google.com> | 2018-11-16 17:26:29 -0800 |
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committer | Herbert Xu <herbert@gondor.apana.org.au> | 2018-11-20 14:26:56 +0800 |
commit | 26609a21a9460145e37d90947ad957b358a05288 (patch) | |
tree | 9f45456ea58fde4464ea71910acf0faf55214555 /crypto/nhpoly1305.c | |
parent | 1b6fd3d5d18bbc1b1abf3b0cbc4b95a9a63d407b (diff) | |
download | linux-26609a21a9460145e37d90947ad957b358a05288.tar.bz2 |
crypto: nhpoly1305 - add NHPoly1305 support
Add a generic implementation of NHPoly1305, an ε-almost-∆-universal hash
function used in the Adiantum encryption mode.
CONFIG_NHPOLY1305 is not selectable by itself since there won't be any
real reason to enable it without also enabling Adiantum support.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/nhpoly1305.c')
-rw-r--r-- | crypto/nhpoly1305.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/crypto/nhpoly1305.c b/crypto/nhpoly1305.c new file mode 100644 index 000000000000..c8385853f699 --- /dev/null +++ b/crypto/nhpoly1305.c @@ -0,0 +1,254 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * NHPoly1305 - ε-almost-∆-universal hash function for Adiantum + * + * Copyright 2018 Google LLC + */ + +/* + * "NHPoly1305" is the main component of Adiantum hashing. + * Specifically, it is the calculation + * + * H_M ← Poly1305_{K_M}(NH_{K_N}(pad_{128}(M))) + * + * from the procedure in section A.5 of the Adiantum paper [1]. It is an + * ε-almost-∆-universal (εA∆U) hash function for equal-length inputs over + * Z/(2^{128}Z), where the "∆" operation is addition. It hashes 1024-byte + * chunks of the input with the NH hash function [2], reducing the input length + * by 32x. The resulting NH digests are evaluated as a polynomial in + * GF(2^{130}-5), like in the Poly1305 MAC [3]. Note that the polynomial + * evaluation by itself would suffice to achieve the εA∆U property; NH is used + * for performance since it's over twice as fast as Poly1305. + * + * This is *not* a cryptographic hash function; do not use it as such! + * + * [1] Adiantum: length-preserving encryption for entry-level processors + * (https://eprint.iacr.org/2018/720.pdf) + * [2] UMAC: Fast and Secure Message Authentication + * (https://fastcrypto.org/umac/umac_proc.pdf) + * [3] The Poly1305-AES message-authentication code + * (https://cr.yp.to/mac/poly1305-20050329.pdf) + */ + +#include <asm/unaligned.h> +#include <crypto/algapi.h> +#include <crypto/internal/hash.h> +#include <crypto/nhpoly1305.h> +#include <linux/crypto.h> +#include <linux/kernel.h> +#include <linux/module.h> + +static void nh_generic(const u32 *key, const u8 *message, size_t message_len, + __le64 hash[NH_NUM_PASSES]) +{ + u64 sums[4] = { 0, 0, 0, 0 }; + + BUILD_BUG_ON(NH_PAIR_STRIDE != 2); + BUILD_BUG_ON(NH_NUM_PASSES != 4); + + while (message_len) { + u32 m0 = get_unaligned_le32(message + 0); + u32 m1 = get_unaligned_le32(message + 4); + u32 m2 = get_unaligned_le32(message + 8); + u32 m3 = get_unaligned_le32(message + 12); + + sums[0] += (u64)(u32)(m0 + key[ 0]) * (u32)(m2 + key[ 2]); + sums[1] += (u64)(u32)(m0 + key[ 4]) * (u32)(m2 + key[ 6]); + sums[2] += (u64)(u32)(m0 + key[ 8]) * (u32)(m2 + key[10]); + sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]); + sums[0] += (u64)(u32)(m1 + key[ 1]) * (u32)(m3 + key[ 3]); + sums[1] += (u64)(u32)(m1 + key[ 5]) * (u32)(m3 + key[ 7]); + sums[2] += (u64)(u32)(m1 + key[ 9]) * (u32)(m3 + key[11]); + sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]); + key += NH_MESSAGE_UNIT / sizeof(key[0]); + message += NH_MESSAGE_UNIT; + message_len -= NH_MESSAGE_UNIT; + } + + hash[0] = cpu_to_le64(sums[0]); + hash[1] = cpu_to_le64(sums[1]); + hash[2] = cpu_to_le64(sums[2]); + hash[3] = cpu_to_le64(sums[3]); +} + +/* Pass the next NH hash value through Poly1305 */ +static void process_nh_hash_value(struct nhpoly1305_state *state, + const struct nhpoly1305_key *key) +{ + BUILD_BUG_ON(NH_HASH_BYTES % POLY1305_BLOCK_SIZE != 0); + + poly1305_core_blocks(&state->poly_state, &key->poly_key, state->nh_hash, + NH_HASH_BYTES / POLY1305_BLOCK_SIZE); +} + +/* + * Feed the next portion of the source data, as a whole number of 16-byte + * "NH message units", through NH and Poly1305. Each NH hash is taken over + * 1024 bytes, except possibly the final one which is taken over a multiple of + * 16 bytes up to 1024. Also, in the case where data is passed in misaligned + * chunks, we combine partial hashes; the end result is the same either way. + */ +static void nhpoly1305_units(struct nhpoly1305_state *state, + const struct nhpoly1305_key *key, + const u8 *src, unsigned int srclen, nh_t nh_fn) +{ + do { + unsigned int bytes; + + if (state->nh_remaining == 0) { + /* Starting a new NH message */ + bytes = min_t(unsigned int, srclen, NH_MESSAGE_BYTES); + nh_fn(key->nh_key, src, bytes, state->nh_hash); + state->nh_remaining = NH_MESSAGE_BYTES - bytes; + } else { + /* Continuing a previous NH message */ + __le64 tmp_hash[NH_NUM_PASSES]; + unsigned int pos; + int i; + + pos = NH_MESSAGE_BYTES - state->nh_remaining; + bytes = min(srclen, state->nh_remaining); + nh_fn(&key->nh_key[pos / 4], src, bytes, tmp_hash); + for (i = 0; i < NH_NUM_PASSES; i++) + le64_add_cpu(&state->nh_hash[i], + le64_to_cpu(tmp_hash[i])); + state->nh_remaining -= bytes; + } + if (state->nh_remaining == 0) + process_nh_hash_value(state, key); + src += bytes; + srclen -= bytes; + } while (srclen); +} + +int crypto_nhpoly1305_setkey(struct crypto_shash *tfm, + const u8 *key, unsigned int keylen) +{ + struct nhpoly1305_key *ctx = crypto_shash_ctx(tfm); + int i; + + if (keylen != NHPOLY1305_KEY_SIZE) + return -EINVAL; + + poly1305_core_setkey(&ctx->poly_key, key); + key += POLY1305_BLOCK_SIZE; + + for (i = 0; i < NH_KEY_WORDS; i++) + ctx->nh_key[i] = get_unaligned_le32(key + i * sizeof(u32)); + + return 0; +} +EXPORT_SYMBOL(crypto_nhpoly1305_setkey); + +int crypto_nhpoly1305_init(struct shash_desc *desc) +{ + struct nhpoly1305_state *state = shash_desc_ctx(desc); + + poly1305_core_init(&state->poly_state); + state->buflen = 0; + state->nh_remaining = 0; + return 0; +} +EXPORT_SYMBOL(crypto_nhpoly1305_init); + +int crypto_nhpoly1305_update_helper(struct shash_desc *desc, + const u8 *src, unsigned int srclen, + nh_t nh_fn) +{ + struct nhpoly1305_state *state = shash_desc_ctx(desc); + const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm); + unsigned int bytes; + + if (state->buflen) { + bytes = min(srclen, (int)NH_MESSAGE_UNIT - state->buflen); + memcpy(&state->buffer[state->buflen], src, bytes); + state->buflen += bytes; + if (state->buflen < NH_MESSAGE_UNIT) + return 0; + nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT, + nh_fn); + state->buflen = 0; + src += bytes; + srclen -= bytes; + } + + if (srclen >= NH_MESSAGE_UNIT) { + bytes = round_down(srclen, NH_MESSAGE_UNIT); + nhpoly1305_units(state, key, src, bytes, nh_fn); + src += bytes; + srclen -= bytes; + } + + if (srclen) { + memcpy(state->buffer, src, srclen); + state->buflen = srclen; + } + return 0; +} +EXPORT_SYMBOL(crypto_nhpoly1305_update_helper); + +int crypto_nhpoly1305_update(struct shash_desc *desc, + const u8 *src, unsigned int srclen) +{ + return crypto_nhpoly1305_update_helper(desc, src, srclen, nh_generic); +} +EXPORT_SYMBOL(crypto_nhpoly1305_update); + +int crypto_nhpoly1305_final_helper(struct shash_desc *desc, u8 *dst, nh_t nh_fn) +{ + struct nhpoly1305_state *state = shash_desc_ctx(desc); + const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm); + + if (state->buflen) { + memset(&state->buffer[state->buflen], 0, + NH_MESSAGE_UNIT - state->buflen); + nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT, + nh_fn); + } + + if (state->nh_remaining) + process_nh_hash_value(state, key); + + poly1305_core_emit(&state->poly_state, dst); + return 0; +} +EXPORT_SYMBOL(crypto_nhpoly1305_final_helper); + +int crypto_nhpoly1305_final(struct shash_desc *desc, u8 *dst) +{ + return crypto_nhpoly1305_final_helper(desc, dst, nh_generic); +} +EXPORT_SYMBOL(crypto_nhpoly1305_final); + +static struct shash_alg nhpoly1305_alg = { + .base.cra_name = "nhpoly1305", + .base.cra_driver_name = "nhpoly1305-generic", + .base.cra_priority = 100, + .base.cra_ctxsize = sizeof(struct nhpoly1305_key), + .base.cra_module = THIS_MODULE, + .digestsize = POLY1305_DIGEST_SIZE, + .init = crypto_nhpoly1305_init, + .update = crypto_nhpoly1305_update, + .final = crypto_nhpoly1305_final, + .setkey = crypto_nhpoly1305_setkey, + .descsize = sizeof(struct nhpoly1305_state), +}; + +static int __init nhpoly1305_mod_init(void) +{ + return crypto_register_shash(&nhpoly1305_alg); +} + +static void __exit nhpoly1305_mod_exit(void) +{ + crypto_unregister_shash(&nhpoly1305_alg); +} + +module_init(nhpoly1305_mod_init); +module_exit(nhpoly1305_mod_exit); + +MODULE_DESCRIPTION("NHPoly1305 ε-almost-∆-universal hash function"); +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>"); +MODULE_ALIAS_CRYPTO("nhpoly1305"); +MODULE_ALIAS_CRYPTO("nhpoly1305-generic"); |