3 * Galois counter mode, specified by NIST,
4 * http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf
6 * See also the gcm paper at
7 * http://www.cryptobarn.com/papers/gcm-spec.pdf.
10 /* nettle, low-level cryptographics library
12 * Copyright (C) 2011 Niels Möller
13 * Copyright (C) 2011 Katholieke Universiteit Leuven
15 * Contributed by Nikos Mavrogiannopoulos
17 * The nettle library is free software; you can redistribute it and/or modify
18 * it under the terms of the GNU Lesser General Public License as published by
19 * the Free Software Foundation; either version 2.1 of the License, or (at your
20 * option) any later version.
22 * The nettle library is distributed in the hope that it will be useful, but
23 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
24 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
25 * License for more details.
27 * You should have received a copy of the GNU Lesser General Public License
28 * along with the nettle library; see the file COPYING.LIB. If not, write to
29 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
44 #include "nettle-internal.h"
47 #define GHASH_POLYNOMIAL 0xE1UL
50 gcm_gf_add (union nettle_block16 *r,
51 const union nettle_block16 *x, const union nettle_block16 *y)
53 r->w[0] = x->w[0] ^ y->w[0];
54 r->w[1] = x->w[1] ^ y->w[1];
56 r->w[2] = x->w[2] ^ y->w[2];
57 r->w[3] = x->w[3] ^ y->w[3];
60 /* Multiplication by 010...0; a big-endian shift right. If the bit
61 shifted out is one, the defining polynomial is added to cancel it
62 out. r == x is allowed. */
64 gcm_gf_shift (union nettle_block16 *r, const union nettle_block16 *x)
68 /* Shift uses big-endian representation. */
71 mask = - (x->w[3] & 1);
72 r->w[3] = (x->w[3] >> 1) | ((x->w[2] & 1) << 31);
73 r->w[2] = (x->w[2] >> 1) | ((x->w[1] & 1) << 31);
74 r->w[1] = (x->w[1] >> 1) | ((x->w[0] & 1) << 31);
75 r->w[0] = (x->w[0] >> 1) ^ (mask & (GHASH_POLYNOMIAL << 24));
76 # elif SIZEOF_LONG == 8
77 mask = - (x->w[1] & 1);
78 r->w[1] = (x->w[1] >> 1) | ((x->w[0] & 1) << 63);
79 r->w[0] = (x->w[0] >> 1) ^ (mask & (GHASH_POLYNOMIAL << 56));
81 # error Unsupported word size. */
83 #else /* ! WORDS_BIGENDIAN */
85 #define RSHIFT_WORD(x) \
86 ((((x) & 0xfefefefeUL) >> 1) \
87 | (((x) & 0x00010101) << 15))
88 mask = - ((x->w[3] >> 24) & 1);
89 r->w[3] = RSHIFT_WORD(x->w[3]) | ((x->w[2] >> 17) & 0x80);
90 r->w[2] = RSHIFT_WORD(x->w[2]) | ((x->w[1] >> 17) & 0x80);
91 r->w[1] = RSHIFT_WORD(x->w[1]) | ((x->w[0] >> 17) & 0x80);
92 r->w[0] = RSHIFT_WORD(x->w[0]) ^ (mask & GHASH_POLYNOMIAL);
93 # elif SIZEOF_LONG == 8
94 #define RSHIFT_WORD(x) \
95 ((((x) & 0xfefefefefefefefeUL) >> 1) \
96 | (((x) & 0x0001010101010101UL) << 15))
97 mask = - ((x->w[1] >> 56) & 1);
98 r->w[1] = RSHIFT_WORD(x->w[1]) | ((x->w[0] >> 49) & 0x80);
99 r->w[0] = RSHIFT_WORD(x->w[0]) ^ (mask & GHASH_POLYNOMIAL);
101 # error Unsupported word size. */
104 #endif /* ! WORDS_BIGENDIAN */
107 #if GCM_TABLE_BITS == 0
108 /* Sets x <- x * y mod r, using the plain bitwise algorithm from the
109 specification. y may be shorter than a full block, missing bytes
112 gcm_gf_mul (union nettle_block16 *x, const union nettle_block16 *y)
114 union nettle_block16 V;
115 union nettle_block16 Z;
118 memcpy(V.b, x, sizeof(V));
119 memset(Z.b, 0, sizeof(Z));
121 for (i = 0; i < GCM_BLOCK_SIZE; i++)
125 for (j = 0; j < 8; j++, b <<= 1)
128 gcm_gf_add(&Z, &Z, &V);
130 gcm_gf_shift(&V, &V);
133 memcpy (x->b, Z.b, sizeof(Z));
135 #else /* GCM_TABLE_BITS != 0 */
138 # define W(left,right) (0x##left##right)
140 # define W(left,right) (0x##right##left)
143 # if GCM_TABLE_BITS == 4
144 static const uint16_t
145 shift_table[0x10] = {
146 W(00,00),W(1c,20),W(38,40),W(24,60),W(70,80),W(6c,a0),W(48,c0),W(54,e0),
147 W(e1,00),W(fd,20),W(d9,40),W(c5,60),W(91,80),W(8d,a0),W(a9,c0),W(b5,e0),
151 gcm_gf_shift_4(union nettle_block16 *x)
153 unsigned long *w = x->w;
154 unsigned long reduce;
156 /* Shift uses big-endian representation. */
158 # if SIZEOF_LONG == 4
159 reduce = shift_table[w[3] & 0xf];
160 w[3] = (w[3] >> 4) | ((w[2] & 0xf) << 28);
161 w[2] = (w[2] >> 4) | ((w[1] & 0xf) << 28);
162 w[1] = (w[1] >> 4) | ((w[0] & 0xf) << 28);
163 w[0] = (w[0] >> 4) ^ (reduce << 16);
164 # elif SIZEOF_LONG == 8
165 reduce = shift_table[w[1] & 0xf];
166 w[1] = (w[1] >> 4) | ((w[0] & 0xf) << 60);
167 w[0] = (w[0] >> 4) ^ (reduce << 48);
169 # error Unsupported word size. */
171 #else /* ! WORDS_BIGENDIAN */
172 # if SIZEOF_LONG == 4
173 #define RSHIFT_WORD(x) \
174 ((((x) & 0xf0f0f0f0UL) >> 4) \
175 | (((x) & 0x000f0f0f) << 12))
176 reduce = shift_table[(w[3] >> 24) & 0xf];
177 w[3] = RSHIFT_WORD(w[3]) | ((w[2] >> 20) & 0xf0);
178 w[2] = RSHIFT_WORD(w[2]) | ((w[1] >> 20) & 0xf0);
179 w[1] = RSHIFT_WORD(w[1]) | ((w[0] >> 20) & 0xf0);
180 w[0] = RSHIFT_WORD(w[0]) ^ reduce;
181 # elif SIZEOF_LONG == 8
182 #define RSHIFT_WORD(x) \
183 ((((x) & 0xf0f0f0f0f0f0f0f0UL) >> 4) \
184 | (((x) & 0x000f0f0f0f0f0f0fUL) << 12))
185 reduce = shift_table[(w[1] >> 56) & 0xf];
186 w[1] = RSHIFT_WORD(w[1]) | ((w[0] >> 52) & 0xf0);
187 w[0] = RSHIFT_WORD(w[0]) ^ reduce;
189 # error Unsupported word size. */
192 #endif /* ! WORDS_BIGENDIAN */
196 gcm_gf_mul (union nettle_block16 *x, const union nettle_block16 *table)
198 union nettle_block16 Z;
201 memset(Z.b, 0, sizeof(Z));
203 for (i = GCM_BLOCK_SIZE; i-- > 0;)
208 gcm_gf_add(&Z, &Z, &table[b & 0xf]);
210 gcm_gf_add(&Z, &Z, &table[b >> 4]);
212 memcpy (x->b, Z.b, sizeof(Z));
214 # elif GCM_TABLE_BITS == 8
215 # if HAVE_NATIVE_gcm_hash8
217 #define gcm_hash _nettle_gcm_hash8
219 _nettle_gcm_hash8 (const struct gcm_key *key, union nettle_block16 *x,
220 size_t length, const uint8_t *data);
221 # else /* !HAVE_NATIVE_gcm_hash8 */
222 static const uint16_t
223 shift_table[0x100] = {
224 W(00,00),W(01,c2),W(03,84),W(02,46),W(07,08),W(06,ca),W(04,8c),W(05,4e),
225 W(0e,10),W(0f,d2),W(0d,94),W(0c,56),W(09,18),W(08,da),W(0a,9c),W(0b,5e),
226 W(1c,20),W(1d,e2),W(1f,a4),W(1e,66),W(1b,28),W(1a,ea),W(18,ac),W(19,6e),
227 W(12,30),W(13,f2),W(11,b4),W(10,76),W(15,38),W(14,fa),W(16,bc),W(17,7e),
228 W(38,40),W(39,82),W(3b,c4),W(3a,06),W(3f,48),W(3e,8a),W(3c,cc),W(3d,0e),
229 W(36,50),W(37,92),W(35,d4),W(34,16),W(31,58),W(30,9a),W(32,dc),W(33,1e),
230 W(24,60),W(25,a2),W(27,e4),W(26,26),W(23,68),W(22,aa),W(20,ec),W(21,2e),
231 W(2a,70),W(2b,b2),W(29,f4),W(28,36),W(2d,78),W(2c,ba),W(2e,fc),W(2f,3e),
232 W(70,80),W(71,42),W(73,04),W(72,c6),W(77,88),W(76,4a),W(74,0c),W(75,ce),
233 W(7e,90),W(7f,52),W(7d,14),W(7c,d6),W(79,98),W(78,5a),W(7a,1c),W(7b,de),
234 W(6c,a0),W(6d,62),W(6f,24),W(6e,e6),W(6b,a8),W(6a,6a),W(68,2c),W(69,ee),
235 W(62,b0),W(63,72),W(61,34),W(60,f6),W(65,b8),W(64,7a),W(66,3c),W(67,fe),
236 W(48,c0),W(49,02),W(4b,44),W(4a,86),W(4f,c8),W(4e,0a),W(4c,4c),W(4d,8e),
237 W(46,d0),W(47,12),W(45,54),W(44,96),W(41,d8),W(40,1a),W(42,5c),W(43,9e),
238 W(54,e0),W(55,22),W(57,64),W(56,a6),W(53,e8),W(52,2a),W(50,6c),W(51,ae),
239 W(5a,f0),W(5b,32),W(59,74),W(58,b6),W(5d,f8),W(5c,3a),W(5e,7c),W(5f,be),
240 W(e1,00),W(e0,c2),W(e2,84),W(e3,46),W(e6,08),W(e7,ca),W(e5,8c),W(e4,4e),
241 W(ef,10),W(ee,d2),W(ec,94),W(ed,56),W(e8,18),W(e9,da),W(eb,9c),W(ea,5e),
242 W(fd,20),W(fc,e2),W(fe,a4),W(ff,66),W(fa,28),W(fb,ea),W(f9,ac),W(f8,6e),
243 W(f3,30),W(f2,f2),W(f0,b4),W(f1,76),W(f4,38),W(f5,fa),W(f7,bc),W(f6,7e),
244 W(d9,40),W(d8,82),W(da,c4),W(db,06),W(de,48),W(df,8a),W(dd,cc),W(dc,0e),
245 W(d7,50),W(d6,92),W(d4,d4),W(d5,16),W(d0,58),W(d1,9a),W(d3,dc),W(d2,1e),
246 W(c5,60),W(c4,a2),W(c6,e4),W(c7,26),W(c2,68),W(c3,aa),W(c1,ec),W(c0,2e),
247 W(cb,70),W(ca,b2),W(c8,f4),W(c9,36),W(cc,78),W(cd,ba),W(cf,fc),W(ce,3e),
248 W(91,80),W(90,42),W(92,04),W(93,c6),W(96,88),W(97,4a),W(95,0c),W(94,ce),
249 W(9f,90),W(9e,52),W(9c,14),W(9d,d6),W(98,98),W(99,5a),W(9b,1c),W(9a,de),
250 W(8d,a0),W(8c,62),W(8e,24),W(8f,e6),W(8a,a8),W(8b,6a),W(89,2c),W(88,ee),
251 W(83,b0),W(82,72),W(80,34),W(81,f6),W(84,b8),W(85,7a),W(87,3c),W(86,fe),
252 W(a9,c0),W(a8,02),W(aa,44),W(ab,86),W(ae,c8),W(af,0a),W(ad,4c),W(ac,8e),
253 W(a7,d0),W(a6,12),W(a4,54),W(a5,96),W(a0,d8),W(a1,1a),W(a3,5c),W(a2,9e),
254 W(b5,e0),W(b4,22),W(b6,64),W(b7,a6),W(b2,e8),W(b3,2a),W(b1,6c),W(b0,ae),
255 W(bb,f0),W(ba,32),W(b8,74),W(b9,b6),W(bc,f8),W(bd,3a),W(bf,7c),W(be,be),
259 gcm_gf_shift_8(union nettle_block16 *x)
261 unsigned long *w = x->w;
262 unsigned long reduce;
264 /* Shift uses big-endian representation. */
266 # if SIZEOF_LONG == 4
267 reduce = shift_table[w[3] & 0xff];
268 w[3] = (w[3] >> 8) | ((w[2] & 0xff) << 24);
269 w[2] = (w[2] >> 8) | ((w[1] & 0xff) << 24);
270 w[1] = (w[1] >> 8) | ((w[0] & 0xff) << 24);
271 w[0] = (w[0] >> 8) ^ (reduce << 16);
272 # elif SIZEOF_LONG == 8
273 reduce = shift_table[w[1] & 0xff];
274 w[1] = (w[1] >> 8) | ((w[0] & 0xff) << 56);
275 w[0] = (w[0] >> 8) ^ (reduce << 48);
277 # error Unsupported word size. */
279 #else /* ! WORDS_BIGENDIAN */
280 # if SIZEOF_LONG == 4
281 reduce = shift_table[(w[3] >> 24) & 0xff];
282 w[3] = (w[3] << 8) | (w[2] >> 24);
283 w[2] = (w[2] << 8) | (w[1] >> 24);
284 w[1] = (w[1] << 8) | (w[0] >> 24);
285 w[0] = (w[0] << 8) ^ reduce;
286 # elif SIZEOF_LONG == 8
287 reduce = shift_table[(w[1] >> 56) & 0xff];
288 w[1] = (w[1] << 8) | (w[0] >> 56);
289 w[0] = (w[0] << 8) ^ reduce;
291 # error Unsupported word size. */
293 #endif /* ! WORDS_BIGENDIAN */
297 gcm_gf_mul (union nettle_block16 *x, const union nettle_block16 *table)
299 union nettle_block16 Z;
302 memcpy(Z.b, table[x->b[GCM_BLOCK_SIZE-1]].b, GCM_BLOCK_SIZE);
304 for (i = GCM_BLOCK_SIZE-2; i > 0; i--)
307 gcm_gf_add(&Z, &Z, &table[x->b[i]]);
310 gcm_gf_add(x, &Z, &table[x->b[0]]);
312 # endif /* ! HAVE_NATIVE_gcm_hash8 */
313 # else /* GCM_TABLE_BITS != 8 */
314 # error Unsupported table size.
315 # endif /* GCM_TABLE_BITS != 8 */
319 #endif /* GCM_TABLE_BITS */
321 /* Increment the rightmost 32 bits. */
322 #define INC32(block) INCREMENT(4, (block.b) + GCM_BLOCK_SIZE - 4)
324 /* Initialization of GCM.
325 * @ctx: The context of GCM
326 * @cipher: The context of the underlying block cipher
327 * @f: The underlying cipher encryption function
330 gcm_set_key(struct gcm_key *key,
331 const void *cipher, nettle_cipher_func *f)
333 /* Middle element if GCM_TABLE_BITS > 0, otherwise the first
335 unsigned i = (1<<GCM_TABLE_BITS)/2;
338 memset(key->h[0].b, 0, GCM_BLOCK_SIZE);
339 f (cipher, GCM_BLOCK_SIZE, key->h[i].b, key->h[0].b);
342 /* Algorithm 3 from the gcm paper. First do powers of two, then do
343 the rest by adding. */
345 gcm_gf_shift(&key->h[i], &key->h[2*i]);
346 for (i = 2; i < 1<<GCM_TABLE_BITS; i *= 2)
349 for (j = 1; j < i; j++)
350 gcm_gf_add(&key->h[i+j], &key->h[i],&key->h[j]);
357 gcm_hash(const struct gcm_key *key, union nettle_block16 *x,
358 size_t length, const uint8_t *data)
360 for (; length >= GCM_BLOCK_SIZE;
361 length -= GCM_BLOCK_SIZE, data += GCM_BLOCK_SIZE)
363 memxor (x->b, data, GCM_BLOCK_SIZE);
364 gcm_gf_mul (x, key->h);
368 memxor (x->b, data, length);
369 gcm_gf_mul (x, key->h);
372 #endif /* !gcm_hash */
375 gcm_hash_sizes(const struct gcm_key *key, union nettle_block16 *x,
376 uint64_t auth_size, uint64_t data_size)
378 uint8_t buffer[GCM_BLOCK_SIZE];
383 WRITE_UINT64 (buffer, auth_size);
384 WRITE_UINT64 (buffer + 8, data_size);
386 gcm_hash(key, x, GCM_BLOCK_SIZE, buffer);
389 /* NOTE: The key is needed only if length != GCM_IV_SIZE */
391 gcm_set_iv(struct gcm_ctx *ctx, const struct gcm_key *key,
392 size_t length, const uint8_t *iv)
394 if (length == GCM_IV_SIZE)
396 memcpy (ctx->iv.b, iv, GCM_BLOCK_SIZE - 4);
397 ctx->iv.b[GCM_BLOCK_SIZE - 4] = 0;
398 ctx->iv.b[GCM_BLOCK_SIZE - 3] = 0;
399 ctx->iv.b[GCM_BLOCK_SIZE - 2] = 0;
400 ctx->iv.b[GCM_BLOCK_SIZE - 1] = 1;
404 memset(ctx->iv.b, 0, GCM_BLOCK_SIZE);
405 gcm_hash(key, &ctx->iv, length, iv);
406 gcm_hash_sizes(key, &ctx->iv, 0, length);
409 memcpy (ctx->ctr.b, ctx->iv.b, GCM_BLOCK_SIZE);
412 /* Reset the rest of the message-dependent state. */
413 memset(ctx->x.b, 0, sizeof(ctx->x));
414 ctx->auth_size = ctx->data_size = 0;
418 gcm_update(struct gcm_ctx *ctx, const struct gcm_key *key,
419 size_t length, const uint8_t *data)
421 assert(ctx->auth_size % GCM_BLOCK_SIZE == 0);
422 assert(ctx->data_size == 0);
424 gcm_hash(key, &ctx->x, length, data);
426 ctx->auth_size += length;
430 gcm_crypt(struct gcm_ctx *ctx, const void *cipher, nettle_cipher_func *f,
431 size_t length, uint8_t *dst, const uint8_t *src)
433 uint8_t buffer[GCM_BLOCK_SIZE];
437 for (; length >= GCM_BLOCK_SIZE;
438 (length -= GCM_BLOCK_SIZE,
439 src += GCM_BLOCK_SIZE, dst += GCM_BLOCK_SIZE))
441 f (cipher, GCM_BLOCK_SIZE, dst, ctx->ctr.b);
442 memxor (dst, src, GCM_BLOCK_SIZE);
448 for (; length >= GCM_BLOCK_SIZE;
449 (length -= GCM_BLOCK_SIZE,
450 src += GCM_BLOCK_SIZE, dst += GCM_BLOCK_SIZE))
452 f (cipher, GCM_BLOCK_SIZE, buffer, ctx->ctr.b);
453 memxor3 (dst, src, buffer, GCM_BLOCK_SIZE);
459 /* A final partial block */
460 f (cipher, GCM_BLOCK_SIZE, buffer, ctx->ctr.b);
461 memxor3 (dst, src, buffer, length);
467 gcm_encrypt (struct gcm_ctx *ctx, const struct gcm_key *key,
468 const void *cipher, nettle_cipher_func *f,
469 size_t length, uint8_t *dst, const uint8_t *src)
471 assert(ctx->data_size % GCM_BLOCK_SIZE == 0);
473 gcm_crypt(ctx, cipher, f, length, dst, src);
474 gcm_hash(key, &ctx->x, length, dst);
476 ctx->data_size += length;
480 gcm_decrypt(struct gcm_ctx *ctx, const struct gcm_key *key,
481 const void *cipher, nettle_cipher_func *f,
482 size_t length, uint8_t *dst, const uint8_t *src)
484 assert(ctx->data_size % GCM_BLOCK_SIZE == 0);
486 gcm_hash(key, &ctx->x, length, src);
487 gcm_crypt(ctx, cipher, f, length, dst, src);
489 ctx->data_size += length;
493 gcm_digest(struct gcm_ctx *ctx, const struct gcm_key *key,
494 const void *cipher, nettle_cipher_func *f,
495 size_t length, uint8_t *digest)
497 uint8_t buffer[GCM_BLOCK_SIZE];
499 assert (length <= GCM_BLOCK_SIZE);
501 gcm_hash_sizes(key, &ctx->x, ctx->auth_size, ctx->data_size);
503 f (cipher, GCM_BLOCK_SIZE, buffer, ctx->iv.b);
504 memxor3 (digest, ctx->x.b, buffer, length);