1 /* 2 * Poly1305 authenticator algorithm, RFC7539 3 * 4 * Copyright (C) 2015 Martin Willi 5 * 6 * Based on public domain code by Andrew Moon and Daniel J. Bernstein. 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 */ 13 14 #include <crypto/algapi.h> 15 #include <crypto/internal/hash.h> 16 #include <crypto/poly1305.h> 17 #include <linux/crypto.h> 18 #include <linux/kernel.h> 19 #include <linux/module.h> 20 #include <asm/unaligned.h> 21 22 static inline u64 mlt(u64 a, u64 b) 23 { 24 return a * b; 25 } 26 27 static inline u32 sr(u64 v, u_char n) 28 { 29 return v >> n; 30 } 31 32 static inline u32 and(u32 v, u32 mask) 33 { 34 return v & mask; 35 } 36 37 int crypto_poly1305_init(struct shash_desc *desc) 38 { 39 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); 40 41 poly1305_core_init(&dctx->h); 42 dctx->buflen = 0; 43 dctx->rset = false; 44 dctx->sset = false; 45 46 return 0; 47 } 48 EXPORT_SYMBOL_GPL(crypto_poly1305_init); 49 50 void poly1305_core_setkey(struct poly1305_key *key, const u8 *raw_key) 51 { 52 /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */ 53 key->r[0] = (get_unaligned_le32(raw_key + 0) >> 0) & 0x3ffffff; 54 key->r[1] = (get_unaligned_le32(raw_key + 3) >> 2) & 0x3ffff03; 55 key->r[2] = (get_unaligned_le32(raw_key + 6) >> 4) & 0x3ffc0ff; 56 key->r[3] = (get_unaligned_le32(raw_key + 9) >> 6) & 0x3f03fff; 57 key->r[4] = (get_unaligned_le32(raw_key + 12) >> 8) & 0x00fffff; 58 } 59 EXPORT_SYMBOL_GPL(poly1305_core_setkey); 60 61 /* 62 * Poly1305 requires a unique key for each tag, which implies that we can't set 63 * it on the tfm that gets accessed by multiple users simultaneously. Instead we 64 * expect the key as the first 32 bytes in the update() call. 65 */ 66 unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx, 67 const u8 *src, unsigned int srclen) 68 { 69 if (!dctx->sset) { 70 if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) { 71 poly1305_core_setkey(&dctx->r, src); 72 src += POLY1305_BLOCK_SIZE; 73 srclen -= POLY1305_BLOCK_SIZE; 74 dctx->rset = true; 75 } 76 if (srclen >= POLY1305_BLOCK_SIZE) { 77 dctx->s[0] = get_unaligned_le32(src + 0); 78 dctx->s[1] = get_unaligned_le32(src + 4); 79 dctx->s[2] = get_unaligned_le32(src + 8); 80 dctx->s[3] = get_unaligned_le32(src + 12); 81 src += POLY1305_BLOCK_SIZE; 82 srclen -= POLY1305_BLOCK_SIZE; 83 dctx->sset = true; 84 } 85 } 86 return srclen; 87 } 88 EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey); 89 90 static void poly1305_blocks_internal(struct poly1305_state *state, 91 const struct poly1305_key *key, 92 const void *src, unsigned int nblocks, 93 u32 hibit) 94 { 95 u32 r0, r1, r2, r3, r4; 96 u32 s1, s2, s3, s4; 97 u32 h0, h1, h2, h3, h4; 98 u64 d0, d1, d2, d3, d4; 99 100 if (!nblocks) 101 return; 102 103 r0 = key->r[0]; 104 r1 = key->r[1]; 105 r2 = key->r[2]; 106 r3 = key->r[3]; 107 r4 = key->r[4]; 108 109 s1 = r1 * 5; 110 s2 = r2 * 5; 111 s3 = r3 * 5; 112 s4 = r4 * 5; 113 114 h0 = state->h[0]; 115 h1 = state->h[1]; 116 h2 = state->h[2]; 117 h3 = state->h[3]; 118 h4 = state->h[4]; 119 120 do { 121 /* h += m[i] */ 122 h0 += (get_unaligned_le32(src + 0) >> 0) & 0x3ffffff; 123 h1 += (get_unaligned_le32(src + 3) >> 2) & 0x3ffffff; 124 h2 += (get_unaligned_le32(src + 6) >> 4) & 0x3ffffff; 125 h3 += (get_unaligned_le32(src + 9) >> 6) & 0x3ffffff; 126 h4 += (get_unaligned_le32(src + 12) >> 8) | hibit; 127 128 /* h *= r */ 129 d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) + 130 mlt(h3, s2) + mlt(h4, s1); 131 d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) + 132 mlt(h3, s3) + mlt(h4, s2); 133 d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) + 134 mlt(h3, s4) + mlt(h4, s3); 135 d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) + 136 mlt(h3, r0) + mlt(h4, s4); 137 d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) + 138 mlt(h3, r1) + mlt(h4, r0); 139 140 /* (partial) h %= p */ 141 d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff); 142 d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff); 143 d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff); 144 d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff); 145 h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff); 146 h1 += h0 >> 26; h0 = h0 & 0x3ffffff; 147 148 src += POLY1305_BLOCK_SIZE; 149 } while (--nblocks); 150 151 state->h[0] = h0; 152 state->h[1] = h1; 153 state->h[2] = h2; 154 state->h[3] = h3; 155 state->h[4] = h4; 156 } 157 158 void poly1305_core_blocks(struct poly1305_state *state, 159 const struct poly1305_key *key, 160 const void *src, unsigned int nblocks) 161 { 162 poly1305_blocks_internal(state, key, src, nblocks, 1 << 24); 163 } 164 EXPORT_SYMBOL_GPL(poly1305_core_blocks); 165 166 static void poly1305_blocks(struct poly1305_desc_ctx *dctx, 167 const u8 *src, unsigned int srclen, u32 hibit) 168 { 169 unsigned int datalen; 170 171 if (unlikely(!dctx->sset)) { 172 datalen = crypto_poly1305_setdesckey(dctx, src, srclen); 173 src += srclen - datalen; 174 srclen = datalen; 175 } 176 177 poly1305_blocks_internal(&dctx->h, &dctx->r, 178 src, srclen / POLY1305_BLOCK_SIZE, hibit); 179 } 180 181 int crypto_poly1305_update(struct shash_desc *desc, 182 const u8 *src, unsigned int srclen) 183 { 184 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); 185 unsigned int bytes; 186 187 if (unlikely(dctx->buflen)) { 188 bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen); 189 memcpy(dctx->buf + dctx->buflen, src, bytes); 190 src += bytes; 191 srclen -= bytes; 192 dctx->buflen += bytes; 193 194 if (dctx->buflen == POLY1305_BLOCK_SIZE) { 195 poly1305_blocks(dctx, dctx->buf, 196 POLY1305_BLOCK_SIZE, 1 << 24); 197 dctx->buflen = 0; 198 } 199 } 200 201 if (likely(srclen >= POLY1305_BLOCK_SIZE)) { 202 poly1305_blocks(dctx, src, srclen, 1 << 24); 203 src += srclen - (srclen % POLY1305_BLOCK_SIZE); 204 srclen %= POLY1305_BLOCK_SIZE; 205 } 206 207 if (unlikely(srclen)) { 208 dctx->buflen = srclen; 209 memcpy(dctx->buf, src, srclen); 210 } 211 212 return 0; 213 } 214 EXPORT_SYMBOL_GPL(crypto_poly1305_update); 215 216 void poly1305_core_emit(const struct poly1305_state *state, void *dst) 217 { 218 u32 h0, h1, h2, h3, h4; 219 u32 g0, g1, g2, g3, g4; 220 u32 mask; 221 222 /* fully carry h */ 223 h0 = state->h[0]; 224 h1 = state->h[1]; 225 h2 = state->h[2]; 226 h3 = state->h[3]; 227 h4 = state->h[4]; 228 229 h2 += (h1 >> 26); h1 = h1 & 0x3ffffff; 230 h3 += (h2 >> 26); h2 = h2 & 0x3ffffff; 231 h4 += (h3 >> 26); h3 = h3 & 0x3ffffff; 232 h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff; 233 h1 += (h0 >> 26); h0 = h0 & 0x3ffffff; 234 235 /* compute h + -p */ 236 g0 = h0 + 5; 237 g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff; 238 g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff; 239 g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff; 240 g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff; 241 242 /* select h if h < p, or h + -p if h >= p */ 243 mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1; 244 g0 &= mask; 245 g1 &= mask; 246 g2 &= mask; 247 g3 &= mask; 248 g4 &= mask; 249 mask = ~mask; 250 h0 = (h0 & mask) | g0; 251 h1 = (h1 & mask) | g1; 252 h2 = (h2 & mask) | g2; 253 h3 = (h3 & mask) | g3; 254 h4 = (h4 & mask) | g4; 255 256 /* h = h % (2^128) */ 257 put_unaligned_le32((h0 >> 0) | (h1 << 26), dst + 0); 258 put_unaligned_le32((h1 >> 6) | (h2 << 20), dst + 4); 259 put_unaligned_le32((h2 >> 12) | (h3 << 14), dst + 8); 260 put_unaligned_le32((h3 >> 18) | (h4 << 8), dst + 12); 261 } 262 EXPORT_SYMBOL_GPL(poly1305_core_emit); 263 264 int crypto_poly1305_final(struct shash_desc *desc, u8 *dst) 265 { 266 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); 267 __le32 digest[4]; 268 u64 f = 0; 269 270 if (unlikely(!dctx->sset)) 271 return -ENOKEY; 272 273 if (unlikely(dctx->buflen)) { 274 dctx->buf[dctx->buflen++] = 1; 275 memset(dctx->buf + dctx->buflen, 0, 276 POLY1305_BLOCK_SIZE - dctx->buflen); 277 poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0); 278 } 279 280 poly1305_core_emit(&dctx->h, digest); 281 282 /* mac = (h + s) % (2^128) */ 283 f = (f >> 32) + le32_to_cpu(digest[0]) + dctx->s[0]; 284 put_unaligned_le32(f, dst + 0); 285 f = (f >> 32) + le32_to_cpu(digest[1]) + dctx->s[1]; 286 put_unaligned_le32(f, dst + 4); 287 f = (f >> 32) + le32_to_cpu(digest[2]) + dctx->s[2]; 288 put_unaligned_le32(f, dst + 8); 289 f = (f >> 32) + le32_to_cpu(digest[3]) + dctx->s[3]; 290 put_unaligned_le32(f, dst + 12); 291 292 return 0; 293 } 294 EXPORT_SYMBOL_GPL(crypto_poly1305_final); 295 296 static struct shash_alg poly1305_alg = { 297 .digestsize = POLY1305_DIGEST_SIZE, 298 .init = crypto_poly1305_init, 299 .update = crypto_poly1305_update, 300 .final = crypto_poly1305_final, 301 .descsize = sizeof(struct poly1305_desc_ctx), 302 .base = { 303 .cra_name = "poly1305", 304 .cra_driver_name = "poly1305-generic", 305 .cra_priority = 100, 306 .cra_blocksize = POLY1305_BLOCK_SIZE, 307 .cra_module = THIS_MODULE, 308 }, 309 }; 310 311 static int __init poly1305_mod_init(void) 312 { 313 return crypto_register_shash(&poly1305_alg); 314 } 315 316 static void __exit poly1305_mod_exit(void) 317 { 318 crypto_unregister_shash(&poly1305_alg); 319 } 320 321 module_init(poly1305_mod_init); 322 module_exit(poly1305_mod_exit); 323 324 MODULE_LICENSE("GPL"); 325 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); 326 MODULE_DESCRIPTION("Poly1305 authenticator"); 327 MODULE_ALIAS_CRYPTO("poly1305"); 328 MODULE_ALIAS_CRYPTO("poly1305-generic"); 329