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[linux-2.6-microblaze.git] / crypto / nhpoly1305.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * NHPoly1305 - ε-almost-∆-universal hash function for Adiantum
4  *
5  * Copyright 2018 Google LLC
6  */
7
8 /*
9  * "NHPoly1305" is the main component of Adiantum hashing.
10  * Specifically, it is the calculation
11  *
12  *      H_L ← Poly1305_{K_L}(NH_{K_N}(pad_{128}(L)))
13  *
14  * from the procedure in section 6.4 of the Adiantum paper [1].  It is an
15  * ε-almost-∆-universal (ε-∆U) hash function for equal-length inputs over
16  * Z/(2^{128}Z), where the "∆" operation is addition.  It hashes 1024-byte
17  * chunks of the input with the NH hash function [2], reducing the input length
18  * by 32x.  The resulting NH digests are evaluated as a polynomial in
19  * GF(2^{130}-5), like in the Poly1305 MAC [3].  Note that the polynomial
20  * evaluation by itself would suffice to achieve the ε-∆U property; NH is used
21  * for performance since it's over twice as fast as Poly1305.
22  *
23  * This is *not* a cryptographic hash function; do not use it as such!
24  *
25  * [1] Adiantum: length-preserving encryption for entry-level processors
26  *     (https://eprint.iacr.org/2018/720.pdf)
27  * [2] UMAC: Fast and Secure Message Authentication
28  *     (https://fastcrypto.org/umac/umac_proc.pdf)
29  * [3] The Poly1305-AES message-authentication code
30  *     (https://cr.yp.to/mac/poly1305-20050329.pdf)
31  */
32
33 #include <asm/unaligned.h>
34 #include <crypto/algapi.h>
35 #include <crypto/internal/hash.h>
36 #include <crypto/nhpoly1305.h>
37 #include <linux/crypto.h>
38 #include <linux/kernel.h>
39 #include <linux/module.h>
40
41 static void nh_generic(const u32 *key, const u8 *message, size_t message_len,
42                        __le64 hash[NH_NUM_PASSES])
43 {
44         u64 sums[4] = { 0, 0, 0, 0 };
45
46         BUILD_BUG_ON(NH_PAIR_STRIDE != 2);
47         BUILD_BUG_ON(NH_NUM_PASSES != 4);
48
49         while (message_len) {
50                 u32 m0 = get_unaligned_le32(message + 0);
51                 u32 m1 = get_unaligned_le32(message + 4);
52                 u32 m2 = get_unaligned_le32(message + 8);
53                 u32 m3 = get_unaligned_le32(message + 12);
54
55                 sums[0] += (u64)(u32)(m0 + key[ 0]) * (u32)(m2 + key[ 2]);
56                 sums[1] += (u64)(u32)(m0 + key[ 4]) * (u32)(m2 + key[ 6]);
57                 sums[2] += (u64)(u32)(m0 + key[ 8]) * (u32)(m2 + key[10]);
58                 sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]);
59                 sums[0] += (u64)(u32)(m1 + key[ 1]) * (u32)(m3 + key[ 3]);
60                 sums[1] += (u64)(u32)(m1 + key[ 5]) * (u32)(m3 + key[ 7]);
61                 sums[2] += (u64)(u32)(m1 + key[ 9]) * (u32)(m3 + key[11]);
62                 sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]);
63                 key += NH_MESSAGE_UNIT / sizeof(key[0]);
64                 message += NH_MESSAGE_UNIT;
65                 message_len -= NH_MESSAGE_UNIT;
66         }
67
68         hash[0] = cpu_to_le64(sums[0]);
69         hash[1] = cpu_to_le64(sums[1]);
70         hash[2] = cpu_to_le64(sums[2]);
71         hash[3] = cpu_to_le64(sums[3]);
72 }
73
74 /* Pass the next NH hash value through Poly1305 */
75 static void process_nh_hash_value(struct nhpoly1305_state *state,
76                                   const struct nhpoly1305_key *key)
77 {
78         BUILD_BUG_ON(NH_HASH_BYTES % POLY1305_BLOCK_SIZE != 0);
79
80         poly1305_core_blocks(&state->poly_state, &key->poly_key, state->nh_hash,
81                              NH_HASH_BYTES / POLY1305_BLOCK_SIZE);
82 }
83
84 /*
85  * Feed the next portion of the source data, as a whole number of 16-byte
86  * "NH message units", through NH and Poly1305.  Each NH hash is taken over
87  * 1024 bytes, except possibly the final one which is taken over a multiple of
88  * 16 bytes up to 1024.  Also, in the case where data is passed in misaligned
89  * chunks, we combine partial hashes; the end result is the same either way.
90  */
91 static void nhpoly1305_units(struct nhpoly1305_state *state,
92                              const struct nhpoly1305_key *key,
93                              const u8 *src, unsigned int srclen, nh_t nh_fn)
94 {
95         do {
96                 unsigned int bytes;
97
98                 if (state->nh_remaining == 0) {
99                         /* Starting a new NH message */
100                         bytes = min_t(unsigned int, srclen, NH_MESSAGE_BYTES);
101                         nh_fn(key->nh_key, src, bytes, state->nh_hash);
102                         state->nh_remaining = NH_MESSAGE_BYTES - bytes;
103                 } else {
104                         /* Continuing a previous NH message */
105                         __le64 tmp_hash[NH_NUM_PASSES];
106                         unsigned int pos;
107                         int i;
108
109                         pos = NH_MESSAGE_BYTES - state->nh_remaining;
110                         bytes = min(srclen, state->nh_remaining);
111                         nh_fn(&key->nh_key[pos / 4], src, bytes, tmp_hash);
112                         for (i = 0; i < NH_NUM_PASSES; i++)
113                                 le64_add_cpu(&state->nh_hash[i],
114                                              le64_to_cpu(tmp_hash[i]));
115                         state->nh_remaining -= bytes;
116                 }
117                 if (state->nh_remaining == 0)
118                         process_nh_hash_value(state, key);
119                 src += bytes;
120                 srclen -= bytes;
121         } while (srclen);
122 }
123
124 int crypto_nhpoly1305_setkey(struct crypto_shash *tfm,
125                              const u8 *key, unsigned int keylen)
126 {
127         struct nhpoly1305_key *ctx = crypto_shash_ctx(tfm);
128         int i;
129
130         if (keylen != NHPOLY1305_KEY_SIZE)
131                 return -EINVAL;
132
133         poly1305_core_setkey(&ctx->poly_key, key);
134         key += POLY1305_BLOCK_SIZE;
135
136         for (i = 0; i < NH_KEY_WORDS; i++)
137                 ctx->nh_key[i] = get_unaligned_le32(key + i * sizeof(u32));
138
139         return 0;
140 }
141 EXPORT_SYMBOL(crypto_nhpoly1305_setkey);
142
143 int crypto_nhpoly1305_init(struct shash_desc *desc)
144 {
145         struct nhpoly1305_state *state = shash_desc_ctx(desc);
146
147         poly1305_core_init(&state->poly_state);
148         state->buflen = 0;
149         state->nh_remaining = 0;
150         return 0;
151 }
152 EXPORT_SYMBOL(crypto_nhpoly1305_init);
153
154 int crypto_nhpoly1305_update_helper(struct shash_desc *desc,
155                                     const u8 *src, unsigned int srclen,
156                                     nh_t nh_fn)
157 {
158         struct nhpoly1305_state *state = shash_desc_ctx(desc);
159         const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);
160         unsigned int bytes;
161
162         if (state->buflen) {
163                 bytes = min(srclen, (int)NH_MESSAGE_UNIT - state->buflen);
164                 memcpy(&state->buffer[state->buflen], src, bytes);
165                 state->buflen += bytes;
166                 if (state->buflen < NH_MESSAGE_UNIT)
167                         return 0;
168                 nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
169                                  nh_fn);
170                 state->buflen = 0;
171                 src += bytes;
172                 srclen -= bytes;
173         }
174
175         if (srclen >= NH_MESSAGE_UNIT) {
176                 bytes = round_down(srclen, NH_MESSAGE_UNIT);
177                 nhpoly1305_units(state, key, src, bytes, nh_fn);
178                 src += bytes;
179                 srclen -= bytes;
180         }
181
182         if (srclen) {
183                 memcpy(state->buffer, src, srclen);
184                 state->buflen = srclen;
185         }
186         return 0;
187 }
188 EXPORT_SYMBOL(crypto_nhpoly1305_update_helper);
189
190 int crypto_nhpoly1305_update(struct shash_desc *desc,
191                              const u8 *src, unsigned int srclen)
192 {
193         return crypto_nhpoly1305_update_helper(desc, src, srclen, nh_generic);
194 }
195 EXPORT_SYMBOL(crypto_nhpoly1305_update);
196
197 int crypto_nhpoly1305_final_helper(struct shash_desc *desc, u8 *dst, nh_t nh_fn)
198 {
199         struct nhpoly1305_state *state = shash_desc_ctx(desc);
200         const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);
201
202         if (state->buflen) {
203                 memset(&state->buffer[state->buflen], 0,
204                        NH_MESSAGE_UNIT - state->buflen);
205                 nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
206                                  nh_fn);
207         }
208
209         if (state->nh_remaining)
210                 process_nh_hash_value(state, key);
211
212         poly1305_core_emit(&state->poly_state, dst);
213         return 0;
214 }
215 EXPORT_SYMBOL(crypto_nhpoly1305_final_helper);
216
217 int crypto_nhpoly1305_final(struct shash_desc *desc, u8 *dst)
218 {
219         return crypto_nhpoly1305_final_helper(desc, dst, nh_generic);
220 }
221 EXPORT_SYMBOL(crypto_nhpoly1305_final);
222
223 static struct shash_alg nhpoly1305_alg = {
224         .base.cra_name          = "nhpoly1305",
225         .base.cra_driver_name   = "nhpoly1305-generic",
226         .base.cra_priority      = 100,
227         .base.cra_ctxsize       = sizeof(struct nhpoly1305_key),
228         .base.cra_module        = THIS_MODULE,
229         .digestsize             = POLY1305_DIGEST_SIZE,
230         .init                   = crypto_nhpoly1305_init,
231         .update                 = crypto_nhpoly1305_update,
232         .final                  = crypto_nhpoly1305_final,
233         .setkey                 = crypto_nhpoly1305_setkey,
234         .descsize               = sizeof(struct nhpoly1305_state),
235 };
236
237 static int __init nhpoly1305_mod_init(void)
238 {
239         return crypto_register_shash(&nhpoly1305_alg);
240 }
241
242 static void __exit nhpoly1305_mod_exit(void)
243 {
244         crypto_unregister_shash(&nhpoly1305_alg);
245 }
246
247 module_init(nhpoly1305_mod_init);
248 module_exit(nhpoly1305_mod_exit);
249
250 MODULE_DESCRIPTION("NHPoly1305 ε-almost-∆-universal hash function");
251 MODULE_LICENSE("GPL v2");
252 MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>");
253 MODULE_ALIAS_CRYPTO("nhpoly1305");
254 MODULE_ALIAS_CRYPTO("nhpoly1305-generic");