126609a21SEric Biggers // SPDX-License-Identifier: GPL-2.0
226609a21SEric Biggers /*
326609a21SEric Biggers * NHPoly1305 - ε-almost-∆-universal hash function for Adiantum
426609a21SEric Biggers *
526609a21SEric Biggers * Copyright 2018 Google LLC
626609a21SEric Biggers */
726609a21SEric Biggers
826609a21SEric Biggers /*
926609a21SEric Biggers * "NHPoly1305" is the main component of Adiantum hashing.
1026609a21SEric Biggers * Specifically, it is the calculation
1126609a21SEric Biggers *
12c6018e1aSEric Biggers * H_L ← Poly1305_{K_L}(NH_{K_N}(pad_{128}(L)))
1326609a21SEric Biggers *
14c6018e1aSEric Biggers * from the procedure in section 6.4 of the Adiantum paper [1]. It is an
15c6018e1aSEric Biggers * ε-almost-∆-universal (ε-∆U) hash function for equal-length inputs over
1626609a21SEric Biggers * Z/(2^{128}Z), where the "∆" operation is addition. It hashes 1024-byte
1726609a21SEric Biggers * chunks of the input with the NH hash function [2], reducing the input length
1826609a21SEric Biggers * by 32x. The resulting NH digests are evaluated as a polynomial in
1926609a21SEric Biggers * GF(2^{130}-5), like in the Poly1305 MAC [3]. Note that the polynomial
20c6018e1aSEric Biggers * evaluation by itself would suffice to achieve the ε-∆U property; NH is used
2126609a21SEric Biggers * for performance since it's over twice as fast as Poly1305.
2226609a21SEric Biggers *
2326609a21SEric Biggers * This is *not* a cryptographic hash function; do not use it as such!
2426609a21SEric Biggers *
2526609a21SEric Biggers * [1] Adiantum: length-preserving encryption for entry-level processors
2626609a21SEric Biggers * (https://eprint.iacr.org/2018/720.pdf)
2726609a21SEric Biggers * [2] UMAC: Fast and Secure Message Authentication
2826609a21SEric Biggers * (https://fastcrypto.org/umac/umac_proc.pdf)
2926609a21SEric Biggers * [3] The Poly1305-AES message-authentication code
3026609a21SEric Biggers * (https://cr.yp.to/mac/poly1305-20050329.pdf)
3126609a21SEric Biggers */
3226609a21SEric Biggers
3326609a21SEric Biggers #include <asm/unaligned.h>
3426609a21SEric Biggers #include <crypto/algapi.h>
3526609a21SEric Biggers #include <crypto/internal/hash.h>
3648ea8c6eSArd Biesheuvel #include <crypto/internal/poly1305.h>
3726609a21SEric Biggers #include <crypto/nhpoly1305.h>
3826609a21SEric Biggers #include <linux/crypto.h>
3926609a21SEric Biggers #include <linux/kernel.h>
4026609a21SEric Biggers #include <linux/module.h>
4126609a21SEric Biggers
nh_generic(const u32 * key,const u8 * message,size_t message_len,__le64 hash[NH_NUM_PASSES])4226609a21SEric Biggers static void nh_generic(const u32 *key, const u8 *message, size_t message_len,
4326609a21SEric Biggers __le64 hash[NH_NUM_PASSES])
4426609a21SEric Biggers {
4526609a21SEric Biggers u64 sums[4] = { 0, 0, 0, 0 };
4626609a21SEric Biggers
4726609a21SEric Biggers BUILD_BUG_ON(NH_PAIR_STRIDE != 2);
4826609a21SEric Biggers BUILD_BUG_ON(NH_NUM_PASSES != 4);
4926609a21SEric Biggers
5026609a21SEric Biggers while (message_len) {
5126609a21SEric Biggers u32 m0 = get_unaligned_le32(message + 0);
5226609a21SEric Biggers u32 m1 = get_unaligned_le32(message + 4);
5326609a21SEric Biggers u32 m2 = get_unaligned_le32(message + 8);
5426609a21SEric Biggers u32 m3 = get_unaligned_le32(message + 12);
5526609a21SEric Biggers
5626609a21SEric Biggers sums[0] += (u64)(u32)(m0 + key[ 0]) * (u32)(m2 + key[ 2]);
5726609a21SEric Biggers sums[1] += (u64)(u32)(m0 + key[ 4]) * (u32)(m2 + key[ 6]);
5826609a21SEric Biggers sums[2] += (u64)(u32)(m0 + key[ 8]) * (u32)(m2 + key[10]);
5926609a21SEric Biggers sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]);
6026609a21SEric Biggers sums[0] += (u64)(u32)(m1 + key[ 1]) * (u32)(m3 + key[ 3]);
6126609a21SEric Biggers sums[1] += (u64)(u32)(m1 + key[ 5]) * (u32)(m3 + key[ 7]);
6226609a21SEric Biggers sums[2] += (u64)(u32)(m1 + key[ 9]) * (u32)(m3 + key[11]);
6326609a21SEric Biggers sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]);
6426609a21SEric Biggers key += NH_MESSAGE_UNIT / sizeof(key[0]);
6526609a21SEric Biggers message += NH_MESSAGE_UNIT;
6626609a21SEric Biggers message_len -= NH_MESSAGE_UNIT;
6726609a21SEric Biggers }
6826609a21SEric Biggers
6926609a21SEric Biggers hash[0] = cpu_to_le64(sums[0]);
7026609a21SEric Biggers hash[1] = cpu_to_le64(sums[1]);
7126609a21SEric Biggers hash[2] = cpu_to_le64(sums[2]);
7226609a21SEric Biggers hash[3] = cpu_to_le64(sums[3]);
7326609a21SEric Biggers }
7426609a21SEric Biggers
7526609a21SEric Biggers /* Pass the next NH hash value through Poly1305 */
process_nh_hash_value(struct nhpoly1305_state * state,const struct nhpoly1305_key * key)7626609a21SEric Biggers static void process_nh_hash_value(struct nhpoly1305_state *state,
7726609a21SEric Biggers const struct nhpoly1305_key *key)
7826609a21SEric Biggers {
7926609a21SEric Biggers BUILD_BUG_ON(NH_HASH_BYTES % POLY1305_BLOCK_SIZE != 0);
8026609a21SEric Biggers
8126609a21SEric Biggers poly1305_core_blocks(&state->poly_state, &key->poly_key, state->nh_hash,
8248ea8c6eSArd Biesheuvel NH_HASH_BYTES / POLY1305_BLOCK_SIZE, 1);
8326609a21SEric Biggers }
8426609a21SEric Biggers
8526609a21SEric Biggers /*
8626609a21SEric Biggers * Feed the next portion of the source data, as a whole number of 16-byte
8726609a21SEric Biggers * "NH message units", through NH and Poly1305. Each NH hash is taken over
8826609a21SEric Biggers * 1024 bytes, except possibly the final one which is taken over a multiple of
8926609a21SEric Biggers * 16 bytes up to 1024. Also, in the case where data is passed in misaligned
9026609a21SEric Biggers * chunks, we combine partial hashes; the end result is the same either way.
9126609a21SEric Biggers */
nhpoly1305_units(struct nhpoly1305_state * state,const struct nhpoly1305_key * key,const u8 * src,unsigned int srclen,nh_t nh_fn)9226609a21SEric Biggers static void nhpoly1305_units(struct nhpoly1305_state *state,
9326609a21SEric Biggers const struct nhpoly1305_key *key,
9426609a21SEric Biggers const u8 *src, unsigned int srclen, nh_t nh_fn)
9526609a21SEric Biggers {
9626609a21SEric Biggers do {
9726609a21SEric Biggers unsigned int bytes;
9826609a21SEric Biggers
9926609a21SEric Biggers if (state->nh_remaining == 0) {
10026609a21SEric Biggers /* Starting a new NH message */
10126609a21SEric Biggers bytes = min_t(unsigned int, srclen, NH_MESSAGE_BYTES);
10226609a21SEric Biggers nh_fn(key->nh_key, src, bytes, state->nh_hash);
10326609a21SEric Biggers state->nh_remaining = NH_MESSAGE_BYTES - bytes;
10426609a21SEric Biggers } else {
10526609a21SEric Biggers /* Continuing a previous NH message */
10626609a21SEric Biggers __le64 tmp_hash[NH_NUM_PASSES];
10726609a21SEric Biggers unsigned int pos;
10826609a21SEric Biggers int i;
10926609a21SEric Biggers
11026609a21SEric Biggers pos = NH_MESSAGE_BYTES - state->nh_remaining;
11126609a21SEric Biggers bytes = min(srclen, state->nh_remaining);
11226609a21SEric Biggers nh_fn(&key->nh_key[pos / 4], src, bytes, tmp_hash);
11326609a21SEric Biggers for (i = 0; i < NH_NUM_PASSES; i++)
11426609a21SEric Biggers le64_add_cpu(&state->nh_hash[i],
11526609a21SEric Biggers le64_to_cpu(tmp_hash[i]));
11626609a21SEric Biggers state->nh_remaining -= bytes;
11726609a21SEric Biggers }
11826609a21SEric Biggers if (state->nh_remaining == 0)
11926609a21SEric Biggers process_nh_hash_value(state, key);
12026609a21SEric Biggers src += bytes;
12126609a21SEric Biggers srclen -= bytes;
12226609a21SEric Biggers } while (srclen);
12326609a21SEric Biggers }
12426609a21SEric Biggers
crypto_nhpoly1305_setkey(struct crypto_shash * tfm,const u8 * key,unsigned int keylen)12526609a21SEric Biggers int crypto_nhpoly1305_setkey(struct crypto_shash *tfm,
12626609a21SEric Biggers const u8 *key, unsigned int keylen)
12726609a21SEric Biggers {
12826609a21SEric Biggers struct nhpoly1305_key *ctx = crypto_shash_ctx(tfm);
12926609a21SEric Biggers int i;
13026609a21SEric Biggers
13126609a21SEric Biggers if (keylen != NHPOLY1305_KEY_SIZE)
13226609a21SEric Biggers return -EINVAL;
13326609a21SEric Biggers
13426609a21SEric Biggers poly1305_core_setkey(&ctx->poly_key, key);
13526609a21SEric Biggers key += POLY1305_BLOCK_SIZE;
13626609a21SEric Biggers
13726609a21SEric Biggers for (i = 0; i < NH_KEY_WORDS; i++)
13826609a21SEric Biggers ctx->nh_key[i] = get_unaligned_le32(key + i * sizeof(u32));
13926609a21SEric Biggers
14026609a21SEric Biggers return 0;
14126609a21SEric Biggers }
14226609a21SEric Biggers EXPORT_SYMBOL(crypto_nhpoly1305_setkey);
14326609a21SEric Biggers
crypto_nhpoly1305_init(struct shash_desc * desc)14426609a21SEric Biggers int crypto_nhpoly1305_init(struct shash_desc *desc)
14526609a21SEric Biggers {
14626609a21SEric Biggers struct nhpoly1305_state *state = shash_desc_ctx(desc);
14726609a21SEric Biggers
14826609a21SEric Biggers poly1305_core_init(&state->poly_state);
14926609a21SEric Biggers state->buflen = 0;
15026609a21SEric Biggers state->nh_remaining = 0;
15126609a21SEric Biggers return 0;
15226609a21SEric Biggers }
15326609a21SEric Biggers EXPORT_SYMBOL(crypto_nhpoly1305_init);
15426609a21SEric Biggers
crypto_nhpoly1305_update_helper(struct shash_desc * desc,const u8 * src,unsigned int srclen,nh_t nh_fn)15526609a21SEric Biggers int crypto_nhpoly1305_update_helper(struct shash_desc *desc,
15626609a21SEric Biggers const u8 *src, unsigned int srclen,
15726609a21SEric Biggers nh_t nh_fn)
15826609a21SEric Biggers {
15926609a21SEric Biggers struct nhpoly1305_state *state = shash_desc_ctx(desc);
16026609a21SEric Biggers const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);
16126609a21SEric Biggers unsigned int bytes;
16226609a21SEric Biggers
16326609a21SEric Biggers if (state->buflen) {
16426609a21SEric Biggers bytes = min(srclen, (int)NH_MESSAGE_UNIT - state->buflen);
16526609a21SEric Biggers memcpy(&state->buffer[state->buflen], src, bytes);
16626609a21SEric Biggers state->buflen += bytes;
16726609a21SEric Biggers if (state->buflen < NH_MESSAGE_UNIT)
16826609a21SEric Biggers return 0;
16926609a21SEric Biggers nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
17026609a21SEric Biggers nh_fn);
17126609a21SEric Biggers state->buflen = 0;
17226609a21SEric Biggers src += bytes;
17326609a21SEric Biggers srclen -= bytes;
17426609a21SEric Biggers }
17526609a21SEric Biggers
17626609a21SEric Biggers if (srclen >= NH_MESSAGE_UNIT) {
17726609a21SEric Biggers bytes = round_down(srclen, NH_MESSAGE_UNIT);
17826609a21SEric Biggers nhpoly1305_units(state, key, src, bytes, nh_fn);
17926609a21SEric Biggers src += bytes;
18026609a21SEric Biggers srclen -= bytes;
18126609a21SEric Biggers }
18226609a21SEric Biggers
18326609a21SEric Biggers if (srclen) {
18426609a21SEric Biggers memcpy(state->buffer, src, srclen);
18526609a21SEric Biggers state->buflen = srclen;
18626609a21SEric Biggers }
18726609a21SEric Biggers return 0;
18826609a21SEric Biggers }
18926609a21SEric Biggers EXPORT_SYMBOL(crypto_nhpoly1305_update_helper);
19026609a21SEric Biggers
crypto_nhpoly1305_update(struct shash_desc * desc,const u8 * src,unsigned int srclen)19126609a21SEric Biggers int crypto_nhpoly1305_update(struct shash_desc *desc,
19226609a21SEric Biggers const u8 *src, unsigned int srclen)
19326609a21SEric Biggers {
19426609a21SEric Biggers return crypto_nhpoly1305_update_helper(desc, src, srclen, nh_generic);
19526609a21SEric Biggers }
19626609a21SEric Biggers EXPORT_SYMBOL(crypto_nhpoly1305_update);
19726609a21SEric Biggers
crypto_nhpoly1305_final_helper(struct shash_desc * desc,u8 * dst,nh_t nh_fn)19826609a21SEric Biggers int crypto_nhpoly1305_final_helper(struct shash_desc *desc, u8 *dst, nh_t nh_fn)
19926609a21SEric Biggers {
20026609a21SEric Biggers struct nhpoly1305_state *state = shash_desc_ctx(desc);
20126609a21SEric Biggers const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);
20226609a21SEric Biggers
20326609a21SEric Biggers if (state->buflen) {
20426609a21SEric Biggers memset(&state->buffer[state->buflen], 0,
20526609a21SEric Biggers NH_MESSAGE_UNIT - state->buflen);
20626609a21SEric Biggers nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
20726609a21SEric Biggers nh_fn);
20826609a21SEric Biggers }
20926609a21SEric Biggers
21026609a21SEric Biggers if (state->nh_remaining)
21126609a21SEric Biggers process_nh_hash_value(state, key);
21226609a21SEric Biggers
213*1c08a104SJason A. Donenfeld poly1305_core_emit(&state->poly_state, NULL, dst);
21426609a21SEric Biggers return 0;
21526609a21SEric Biggers }
21626609a21SEric Biggers EXPORT_SYMBOL(crypto_nhpoly1305_final_helper);
21726609a21SEric Biggers
crypto_nhpoly1305_final(struct shash_desc * desc,u8 * dst)21826609a21SEric Biggers int crypto_nhpoly1305_final(struct shash_desc *desc, u8 *dst)
21926609a21SEric Biggers {
22026609a21SEric Biggers return crypto_nhpoly1305_final_helper(desc, dst, nh_generic);
22126609a21SEric Biggers }
22226609a21SEric Biggers EXPORT_SYMBOL(crypto_nhpoly1305_final);
22326609a21SEric Biggers
22426609a21SEric Biggers static struct shash_alg nhpoly1305_alg = {
22526609a21SEric Biggers .base.cra_name = "nhpoly1305",
22626609a21SEric Biggers .base.cra_driver_name = "nhpoly1305-generic",
22726609a21SEric Biggers .base.cra_priority = 100,
22826609a21SEric Biggers .base.cra_ctxsize = sizeof(struct nhpoly1305_key),
22926609a21SEric Biggers .base.cra_module = THIS_MODULE,
23026609a21SEric Biggers .digestsize = POLY1305_DIGEST_SIZE,
23126609a21SEric Biggers .init = crypto_nhpoly1305_init,
23226609a21SEric Biggers .update = crypto_nhpoly1305_update,
23326609a21SEric Biggers .final = crypto_nhpoly1305_final,
23426609a21SEric Biggers .setkey = crypto_nhpoly1305_setkey,
23526609a21SEric Biggers .descsize = sizeof(struct nhpoly1305_state),
23626609a21SEric Biggers };
23726609a21SEric Biggers
nhpoly1305_mod_init(void)23826609a21SEric Biggers static int __init nhpoly1305_mod_init(void)
23926609a21SEric Biggers {
24026609a21SEric Biggers return crypto_register_shash(&nhpoly1305_alg);
24126609a21SEric Biggers }
24226609a21SEric Biggers
nhpoly1305_mod_exit(void)24326609a21SEric Biggers static void __exit nhpoly1305_mod_exit(void)
24426609a21SEric Biggers {
24526609a21SEric Biggers crypto_unregister_shash(&nhpoly1305_alg);
24626609a21SEric Biggers }
24726609a21SEric Biggers
248c4741b23SEric Biggers subsys_initcall(nhpoly1305_mod_init);
24926609a21SEric Biggers module_exit(nhpoly1305_mod_exit);
25026609a21SEric Biggers
25126609a21SEric Biggers MODULE_DESCRIPTION("NHPoly1305 ε-almost-∆-universal hash function");
25226609a21SEric Biggers MODULE_LICENSE("GPL v2");
25326609a21SEric Biggers MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>");
25426609a21SEric Biggers MODULE_ALIAS_CRYPTO("nhpoly1305");
25526609a21SEric Biggers MODULE_ALIAS_CRYPTO("nhpoly1305-generic");
256