1 | /* |
2 | * Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved. |
3 | * |
4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
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" |
17 | #include "prov/providercommon.h" |
18 | #include "rand_local.h" |
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 | { |
293 | EVP_MD_free(drbg->data.hash.md); |
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 | { |
308 | EVP_MD *md; |
309 | RAND_DRBG_HASH *hash = &drbg->data.hash; |
310 | |
311 | /* |
312 | * Confirm digest is allowed. We allow all digests that are not XOF |
313 | * (such as SHAKE). In FIPS mode, the fetch will fail for non-approved |
314 | * digests. |
315 | */ |
316 | md = EVP_MD_fetch(drbg->libctx, ossl_prov_util_nid_to_name(drbg->type), "" ); |
317 | if (md == NULL) |
318 | return 0; |
319 | |
320 | if ((EVP_MD_flags(md) & EVP_MD_FLAG_XOF) != 0) |
321 | return 0; |
322 | |
323 | drbg->meth = &drbg_hash_meth; |
324 | |
325 | if (hash->ctx == NULL) { |
326 | hash->ctx = EVP_MD_CTX_new(); |
327 | if (hash->ctx == NULL) { |
328 | EVP_MD_free(md); |
329 | return 0; |
330 | } |
331 | } |
332 | |
333 | EVP_MD_free(hash->md); |
334 | hash->md = md; |
335 | |
336 | /* These are taken from SP 800-90 10.1 Table 2 */ |
337 | hash->blocklen = EVP_MD_size(md); |
338 | /* See SP800-57 Part1 Rev4 5.6.1 Table 3 */ |
339 | drbg->strength = 64 * (hash->blocklen >> 3); |
340 | if (drbg->strength > 256) |
341 | drbg->strength = 256; |
342 | if (hash->blocklen > MAX_BLOCKLEN_USING_SMALL_SEEDLEN) |
343 | drbg->seedlen = HASH_PRNG_MAX_SEEDLEN; |
344 | else |
345 | drbg->seedlen = HASH_PRNG_SMALL_SEEDLEN; |
346 | |
347 | drbg->min_entropylen = drbg->strength / 8; |
348 | drbg->max_entropylen = DRBG_MAX_LENGTH; |
349 | |
350 | drbg->min_noncelen = drbg->min_entropylen / 2; |
351 | drbg->max_noncelen = DRBG_MAX_LENGTH; |
352 | |
353 | drbg->max_perslen = DRBG_MAX_LENGTH; |
354 | drbg->max_adinlen = DRBG_MAX_LENGTH; |
355 | |
356 | /* Maximum number of bits per request = 2^19 = 2^16 bytes */ |
357 | drbg->max_request = 1 << 16; |
358 | |
359 | return 1; |
360 | } |
361 | |