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8bf36651 SL |
1 | /* |
2 | * Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved. | |
3 | * | |
0db63de9 | 4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
8bf36651 SL |
5 | * this file except in compliance with the License. You can obtain a copy |
6 | * in the file LICENSE in the source distribution or at | |
7 | * https://www.openssl.org/source/license.html | |
8 | */ | |
9 | ||
10 | #include <assert.h> | |
11 | #include <stdlib.h> | |
12 | #include <string.h> | |
13 | #include <openssl/crypto.h> | |
14 | #include <openssl/err.h> | |
15 | #include <openssl/rand.h> | |
16 | #include "internal/thread_once.h" | |
ddd21319 | 17 | #include "prov/providercommon.h" |
706457b7 | 18 | #include "rand_local.h" |
8bf36651 SL |
19 | |
20 | /* 440 bits from SP800-90Ar1 10.1 table 2 */ | |
21 | #define HASH_PRNG_SMALL_SEEDLEN (440/8) | |
22 | /* Determine what seedlen to use based on the block length */ | |
23 | #define MAX_BLOCKLEN_USING_SMALL_SEEDLEN (256/8) | |
24 | #define INBYTE_IGNORE ((unsigned char)0xFF) | |
25 | ||
26 | ||
27 | /* | |
28 | * SP800-90Ar1 10.3.1 Derivation function using a Hash Function (Hash_df). | |
29 | * The input string used is composed of: | |
30 | * inbyte - An optional leading byte (ignore if equal to INBYTE_IGNORE) | |
31 | * in - input string 1 (A Non NULL value). | |
32 | * in2 - optional input string (Can be NULL). | |
33 | * in3 - optional input string (Can be NULL). | |
34 | * These are concatenated as part of the DigestUpdate process. | |
35 | */ | |
36 | static int hash_df(RAND_DRBG *drbg, unsigned char *out, | |
37 | const unsigned char inbyte, | |
38 | const unsigned char *in, size_t inlen, | |
39 | const unsigned char *in2, size_t in2len, | |
40 | const unsigned char *in3, size_t in3len) | |
41 | { | |
42 | RAND_DRBG_HASH *hash = &drbg->data.hash; | |
43 | EVP_MD_CTX *ctx = hash->ctx; | |
44 | unsigned char *vtmp = hash->vtmp; | |
45 | /* tmp = counter || num_bits_returned || [inbyte] */ | |
46 | unsigned char tmp[1 + 4 + 1]; | |
47 | int tmp_sz = 0; | |
48 | size_t outlen = drbg->seedlen; | |
49 | size_t num_bits_returned = outlen * 8; | |
50 | /* | |
51 | * No need to check outlen size here, as the standard only ever needs | |
52 | * seedlen bytes which is always less than the maximum permitted. | |
53 | */ | |
54 | ||
55 | /* (Step 3) counter = 1 (tmp[0] is the 8 bit counter) */ | |
56 | tmp[tmp_sz++] = 1; | |
57 | /* tmp[1..4] is the fixed 32 bit no_of_bits_to_return */ | |
58 | tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 24) & 0xff); | |
59 | tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 16) & 0xff); | |
60 | tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 8) & 0xff); | |
61 | tmp[tmp_sz++] = (unsigned char)(num_bits_returned & 0xff); | |
62 | /* Tack the additional input byte onto the end of tmp if it exists */ | |
63 | if (inbyte != INBYTE_IGNORE) | |
64 | tmp[tmp_sz++] = inbyte; | |
65 | ||
66 | /* (Step 4) */ | |
67 | for (;;) { | |
68 | /* | |
69 | * (Step 4.1) out = out || Hash(tmp || in || [in2] || [in3]) | |
70 | * (where tmp = counter || num_bits_returned || [inbyte]) | |
71 | */ | |
72 | if (!(EVP_DigestInit_ex(ctx, hash->md, NULL) | |
73 | && EVP_DigestUpdate(ctx, tmp, tmp_sz) | |
74 | && EVP_DigestUpdate(ctx, in, inlen) | |
75 | && (in2 == NULL || EVP_DigestUpdate(ctx, in2, in2len)) | |
76 | && (in3 == NULL || EVP_DigestUpdate(ctx, in3, in3len)))) | |
77 | return 0; | |
78 | ||
79 | if (outlen < hash->blocklen) { | |
80 | if (!EVP_DigestFinal(ctx, vtmp, NULL)) | |
81 | return 0; | |
82 | memcpy(out, vtmp, outlen); | |
83 | OPENSSL_cleanse(vtmp, hash->blocklen); | |
84 | break; | |
85 | } else if(!EVP_DigestFinal(ctx, out, NULL)) { | |
86 | return 0; | |
87 | } | |
88 | ||
89 | outlen -= hash->blocklen; | |
90 | if (outlen == 0) | |
91 | break; | |
92 | /* (Step 4.2) counter++ */ | |
93 | tmp[0]++; | |
94 | out += hash->blocklen; | |
95 | } | |
96 | return 1; | |
97 | } | |
98 | ||
99 | /* Helper function that just passes 2 input parameters to hash_df() */ | |
100 | static int hash_df1(RAND_DRBG *drbg, unsigned char *out, | |
101 | const unsigned char in_byte, | |
102 | const unsigned char *in1, size_t in1len) | |
103 | { | |
104 | return hash_df(drbg, out, in_byte, in1, in1len, NULL, 0, NULL, 0); | |
105 | } | |
106 | ||
107 | /* | |
108 | * Add 2 byte buffers together. The first elements in each buffer are the top | |
109 | * most bytes. The result is stored in the dst buffer. | |
110 | * The final carry is ignored i.e: dst = (dst + in) mod (2^seedlen_bits). | |
111 | * where dst size is drbg->seedlen, and inlen <= drbg->seedlen. | |
112 | */ | |
113 | static int add_bytes(RAND_DRBG *drbg, unsigned char *dst, | |
114 | unsigned char *in, size_t inlen) | |
115 | { | |
116 | size_t i; | |
117 | int result; | |
118 | const unsigned char *add; | |
119 | unsigned char carry = 0, *d; | |
120 | ||
121 | assert(drbg->seedlen >= 1 && inlen >= 1 && inlen <= drbg->seedlen); | |
122 | ||
123 | d = &dst[drbg->seedlen - 1]; | |
124 | add = &in[inlen - 1]; | |
125 | ||
126 | for (i = inlen; i > 0; i--, d--, add--) { | |
127 | result = *d + *add + carry; | |
128 | carry = (unsigned char)(result >> 8); | |
129 | *d = (unsigned char)(result & 0xff); | |
130 | } | |
131 | ||
132 | if (carry != 0) { | |
133 | /* Add the carry to the top of the dst if inlen is not the same size */ | |
134 | for (i = drbg->seedlen - inlen; i > 0; --i, d--) { | |
135 | *d += 1; /* Carry can only be 1 */ | |
136 | if (*d != 0) /* exit if carry doesnt propagate to the next byte */ | |
137 | break; | |
138 | } | |
139 | } | |
140 | return 1; | |
141 | } | |
142 | ||
143 | /* V = (V + Hash(inbyte || V || [additional_input]) mod (2^seedlen) */ | |
144 | static int add_hash_to_v(RAND_DRBG *drbg, unsigned char inbyte, | |
145 | const unsigned char *adin, size_t adinlen) | |
146 | { | |
147 | RAND_DRBG_HASH *hash = &drbg->data.hash; | |
148 | EVP_MD_CTX *ctx = hash->ctx; | |
149 | ||
150 | return EVP_DigestInit_ex(ctx, hash->md, NULL) | |
151 | && EVP_DigestUpdate(ctx, &inbyte, 1) | |
152 | && EVP_DigestUpdate(ctx, hash->V, drbg->seedlen) | |
153 | && (adin == NULL || EVP_DigestUpdate(ctx, adin, adinlen)) | |
154 | && EVP_DigestFinal(ctx, hash->vtmp, NULL) | |
155 | && add_bytes(drbg, hash->V, hash->vtmp, hash->blocklen); | |
156 | } | |
157 | ||
158 | /* | |
159 | * The Hashgen() as listed in SP800-90Ar1 10.1.1.4 Hash_DRBG_Generate_Process. | |
160 | * | |
161 | * drbg contains the current value of V. | |
162 | * outlen is the requested number of bytes. | |
163 | * out is a buffer to return the generated bits. | |
164 | * | |
165 | * The algorithm to generate the bits is: | |
166 | * data = V | |
167 | * w = NULL | |
168 | * for (i = 1 to m) { | |
169 | * W = W || Hash(data) | |
170 | * data = (data + 1) mod (2^seedlen) | |
171 | * } | |
172 | * out = Leftmost(W, outlen) | |
173 | * | |
174 | * Returns zero if an error occurs otherwise it returns 1. | |
175 | */ | |
176 | static int hash_gen(RAND_DRBG *drbg, unsigned char *out, size_t outlen) | |
177 | { | |
178 | RAND_DRBG_HASH *hash = &drbg->data.hash; | |
179 | unsigned char one = 1; | |
180 | ||
181 | if (outlen == 0) | |
182 | return 1; | |
183 | memcpy(hash->vtmp, hash->V, drbg->seedlen); | |
184 | for(;;) { | |
185 | if (!EVP_DigestInit_ex(hash->ctx, hash->md, NULL) | |
186 | || !EVP_DigestUpdate(hash->ctx, hash->vtmp, drbg->seedlen)) | |
187 | return 0; | |
188 | ||
189 | if (outlen < hash->blocklen) { | |
190 | if (!EVP_DigestFinal(hash->ctx, hash->vtmp, NULL)) | |
191 | return 0; | |
192 | memcpy(out, hash->vtmp, outlen); | |
193 | return 1; | |
194 | } else { | |
195 | if (!EVP_DigestFinal(hash->ctx, out, NULL)) | |
196 | return 0; | |
197 | outlen -= hash->blocklen; | |
198 | if (outlen == 0) | |
199 | break; | |
200 | out += hash->blocklen; | |
201 | } | |
202 | add_bytes(drbg, hash->vtmp, &one, 1); | |
203 | } | |
204 | return 1; | |
205 | } | |
206 | ||
207 | /* | |
208 | * SP800-90Ar1 10.1.1.2 Hash_DRBG_Instantiate_Process: | |
209 | * | |
210 | * ent is entropy input obtained from a randomness source of length ent_len. | |
211 | * nonce is a string of bytes of length nonce_len. | |
212 | * pstr is a personalization string received from an application. May be NULL. | |
213 | * | |
214 | * Returns zero if an error occurs otherwise it returns 1. | |
215 | */ | |
216 | static int drbg_hash_instantiate(RAND_DRBG *drbg, | |
217 | const unsigned char *ent, size_t ent_len, | |
218 | const unsigned char *nonce, size_t nonce_len, | |
219 | const unsigned char *pstr, size_t pstr_len) | |
220 | { | |
221 | RAND_DRBG_HASH *hash = &drbg->data.hash; | |
222 | ||
223 | /* (Step 1-3) V = Hash_df(entropy||nonce||pers, seedlen) */ | |
224 | return hash_df(drbg, hash->V, INBYTE_IGNORE, | |
225 | ent, ent_len, nonce, nonce_len, pstr, pstr_len) | |
226 | /* (Step 4) C = Hash_df(0x00||V, seedlen) */ | |
227 | && hash_df1(drbg, hash->C, 0x00, hash->V, drbg->seedlen); | |
228 | } | |
229 | ||
230 | /* | |
231 | * SP800-90Ar1 10.1.1.3 Hash_DRBG_Reseed_Process: | |
232 | * | |
233 | * ent is entropy input bytes obtained from a randomness source. | |
234 | * addin is additional input received from an application. May be NULL. | |
235 | * | |
236 | * Returns zero if an error occurs otherwise it returns 1. | |
237 | */ | |
238 | static int drbg_hash_reseed(RAND_DRBG *drbg, | |
239 | const unsigned char *ent, size_t ent_len, | |
240 | const unsigned char *adin, size_t adin_len) | |
241 | { | |
242 | RAND_DRBG_HASH *hash = &drbg->data.hash; | |
243 | ||
244 | /* (Step 1-2) V = Hash_df(0x01 || V || entropy_input || additional_input)*/ | |
245 | /* V about to be updated so use C as output instead */ | |
246 | if (!hash_df(drbg, hash->C, 0x01, hash->V, drbg->seedlen, ent, ent_len, | |
247 | adin, adin_len)) | |
248 | return 0; | |
249 | memcpy(hash->V, hash->C, drbg->seedlen); | |
250 | /* (Step 4) C = Hash_df(0x00||V, seedlen) */ | |
251 | return hash_df1(drbg, hash->C, 0x00, hash->V, drbg->seedlen); | |
252 | } | |
253 | ||
254 | /* | |
255 | * SP800-90Ar1 10.1.1.4 Hash_DRBG_Generate_Process: | |
256 | * | |
257 | * Generates pseudo random bytes using the drbg. | |
258 | * out is a buffer to fill with outlen bytes of pseudo random data. | |
259 | * addin is additional input received from an application. May be NULL. | |
260 | * | |
261 | * Returns zero if an error occurs otherwise it returns 1. | |
262 | */ | |
263 | static int drbg_hash_generate(RAND_DRBG *drbg, | |
264 | unsigned char *out, size_t outlen, | |
265 | const unsigned char *adin, size_t adin_len) | |
266 | { | |
267 | RAND_DRBG_HASH *hash = &drbg->data.hash; | |
268 | unsigned char counter[4]; | |
269 | int reseed_counter = drbg->reseed_gen_counter; | |
270 | ||
271 | counter[0] = (unsigned char)((reseed_counter >> 24) & 0xff); | |
272 | counter[1] = (unsigned char)((reseed_counter >> 16) & 0xff); | |
273 | counter[2] = (unsigned char)((reseed_counter >> 8) & 0xff); | |
274 | counter[3] = (unsigned char)(reseed_counter & 0xff); | |
275 | ||
276 | return (adin == NULL | |
277 | /* (Step 2) if adin != NULL then V = V + Hash(0x02||V||adin) */ | |
278 | || adin_len == 0 | |
279 | || add_hash_to_v(drbg, 0x02, adin, adin_len)) | |
280 | /* (Step 3) Hashgen(outlen, V) */ | |
281 | && hash_gen(drbg, out, outlen) | |
282 | /* (Step 4/5) H = V = (V + Hash(0x03||V) mod (2^seedlen_bits) */ | |
283 | && add_hash_to_v(drbg, 0x03, NULL, 0) | |
284 | /* (Step 5) V = (V + H + C + reseed_counter) mod (2^seedlen_bits) */ | |
285 | /* V = (V + C) mod (2^seedlen_bits) */ | |
286 | && add_bytes(drbg, hash->V, hash->C, drbg->seedlen) | |
287 | /* V = (V + reseed_counter) mod (2^seedlen_bits) */ | |
288 | && add_bytes(drbg, hash->V, counter, 4); | |
289 | } | |
290 | ||
291 | static int drbg_hash_uninstantiate(RAND_DRBG *drbg) | |
292 | { | |
3fd70262 | 293 | EVP_MD_free(drbg->data.hash.md); |
8bf36651 SL |
294 | EVP_MD_CTX_free(drbg->data.hash.ctx); |
295 | OPENSSL_cleanse(&drbg->data.hash, sizeof(drbg->data.hash)); | |
296 | return 1; | |
297 | } | |
298 | ||
299 | static RAND_DRBG_METHOD drbg_hash_meth = { | |
300 | drbg_hash_instantiate, | |
301 | drbg_hash_reseed, | |
302 | drbg_hash_generate, | |
303 | drbg_hash_uninstantiate | |
304 | }; | |
305 | ||
306 | int drbg_hash_init(RAND_DRBG *drbg) | |
307 | { | |
57ca171a | 308 | EVP_MD *md; |
8bf36651 SL |
309 | RAND_DRBG_HASH *hash = &drbg->data.hash; |
310 | ||
671aaecd MC |
311 | /* |
312 | * Confirm digest is allowed. Outside FIPS_MODE we allow all non-legacy | |
313 | * digests. Inside FIPS_MODE we only allow approved digests. Also no XOF | |
314 | * digests (such as SHAKE). | |
315 | */ | |
57ca171a MC |
316 | switch (drbg->type) { |
317 | default: | |
318 | return 0; | |
671aaecd MC |
319 | |
320 | case NID_sha1: | |
321 | case NID_sha224: | |
57ca171a | 322 | case NID_sha256: |
671aaecd MC |
323 | case NID_sha384: |
324 | case NID_sha512: | |
325 | case NID_sha512_224: | |
326 | case NID_sha512_256: | |
327 | case NID_sha3_224: | |
328 | case NID_sha3_256: | |
329 | case NID_sha3_384: | |
330 | case NID_sha3_512: | |
331 | #ifndef FIPS_MODE | |
332 | case NID_blake2b512: | |
333 | case NID_blake2s256: | |
334 | case NID_sm3: | |
335 | #endif | |
57ca171a MC |
336 | break; |
337 | } | |
671aaecd MC |
338 | |
339 | md = EVP_MD_fetch(drbg->libctx, ossl_prov_util_nid_to_name(drbg->type), ""); | |
8bf36651 SL |
340 | if (md == NULL) |
341 | return 0; | |
342 | ||
57ca171a | 343 | |
8bf36651 | 344 | drbg->meth = &drbg_hash_meth; |
8bf36651 SL |
345 | |
346 | if (hash->ctx == NULL) { | |
347 | hash->ctx = EVP_MD_CTX_new(); | |
57ca171a | 348 | if (hash->ctx == NULL) { |
3fd70262 | 349 | EVP_MD_free(md); |
8bf36651 | 350 | return 0; |
57ca171a | 351 | } |
8bf36651 SL |
352 | } |
353 | ||
3fd70262 | 354 | EVP_MD_free(hash->md); |
57ca171a MC |
355 | hash->md = md; |
356 | ||
8bf36651 SL |
357 | /* These are taken from SP 800-90 10.1 Table 2 */ |
358 | hash->blocklen = EVP_MD_size(md); | |
359 | /* See SP800-57 Part1 Rev4 5.6.1 Table 3 */ | |
360 | drbg->strength = 64 * (hash->blocklen >> 3); | |
361 | if (drbg->strength > 256) | |
362 | drbg->strength = 256; | |
363 | if (hash->blocklen > MAX_BLOCKLEN_USING_SMALL_SEEDLEN) | |
364 | drbg->seedlen = HASH_PRNG_MAX_SEEDLEN; | |
365 | else | |
366 | drbg->seedlen = HASH_PRNG_SMALL_SEEDLEN; | |
367 | ||
368 | drbg->min_entropylen = drbg->strength / 8; | |
3064b551 | 369 | drbg->max_entropylen = DRBG_MAX_LENGTH; |
8bf36651 SL |
370 | |
371 | drbg->min_noncelen = drbg->min_entropylen / 2; | |
3064b551 | 372 | drbg->max_noncelen = DRBG_MAX_LENGTH; |
8bf36651 SL |
373 | |
374 | drbg->max_perslen = DRBG_MAX_LENGTH; | |
375 | drbg->max_adinlen = DRBG_MAX_LENGTH; | |
376 | ||
377 | /* Maximum number of bits per request = 2^19 = 2^16 bytes */ | |
378 | drbg->max_request = 1 << 16; | |
379 | ||
380 | return 1; | |
381 | } |