// 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_L ← Poly1305_{K_L}(NH_{K_N}(pad_{128}(L))) * * from the procedure in section 6.4 of the Adiantum paper [1]. It is an * ε-almost-∆-universal (ε-∆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 ε-∆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); } subsys_initcall(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");