1 /* Copyright (c) (2014-2019,2021,2022) Apple Inc. All rights reserved.
2 *
3 * corecrypto is licensed under Apple Inc.’s Internal Use License Agreement (which
4 * is contained in the License.txt file distributed with corecrypto) and only to
5 * people who accept that license. IMPORTANT: Any license rights granted to you by
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8 * security characteristics and correct functioning of the Apple Software. You may
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10 *
11 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
12 *
13 * This file contains Original Code and/or Modifications of Original Code
14 * as defined in and that are subject to the Apple Public Source License
15 * Version 2.0 (the 'License'). You may not use this file except in
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17 * may not be used to create, or enable the creation or redistribution of,
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21 *
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28 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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34 */
35
36 #include "cc_internal.h"
37
38 #include <corecrypto/cc_priv.h>
39 #include <corecrypto/ccdrbg.h>
40 #include <corecrypto/cchmac.h>
41 #include <corecrypto/ccsha2.h>
42 #include "cc_macros.h"
43
44 // This HMAC DRBG is described in:
45
46 // NIST SP 800-90A Rev. 1
47 // Recommendation for Random Number Generation Using Deterministic Random Bit Generators
48 // June 2015
49
50 // See in particular:
51 // - 9 DRBG Mechanism Functions
52 // - 10.1.2 HMAC_DRBG
53 // - B.2 HMAC_DRBGExample
54
55 #define DRBG_HMAC_MAX_OUTPUT_SIZE MAX_DIGEST_OUTPUT_SIZE
56
57 #define MIN_REQ_ENTROPY(di) ((di)->output_size / 2)
58
59 struct ccdrbg_nisthmac_state {
60 const struct ccdrbg_nisthmac_custom *custom;
61 uint8_t key[DRBG_HMAC_MAX_OUTPUT_SIZE];
62 uint8_t V[DRBG_HMAC_MAX_OUTPUT_SIZE];
63 uint64_t reseed_counter;
64 };
65
66 #define DRBG_NISTHMAC_DEBUG 0
67
68 #if DRBG_NISTHMAC_DEBUG
69 #include "cc_debug.h"
70
71 static void
dump_state(const char * label,struct ccdrbg_nisthmac_state * drbg_ctx)72 dump_state(const char *label, struct ccdrbg_nisthmac_state *drbg_ctx)
73 {
74 size_t outlen = drbg_ctx->custom->di->output_size;
75
76 cc_print(label, outlen, drbg_ctx->key);
77 cc_print(label, outlen, drbg_ctx->V);
78 }
79 #endif
80
81 // See NIST SP 800-90A, Rev. 1, 9.4
82 static void
done(struct ccdrbg_state * ctx)83 done(struct ccdrbg_state *ctx)
84 {
85 struct ccdrbg_nisthmac_state *drbg_ctx = (struct ccdrbg_nisthmac_state *)ctx;
86 cc_clear(sizeof(drbg_ctx->key), drbg_ctx->key);
87 cc_clear(sizeof(drbg_ctx->V), drbg_ctx->V);
88 drbg_ctx->reseed_counter = UINT64_MAX;
89 }
90
91 // See NIST SP 800-90A, Rev. 1, 10.1.2.2
92 static void
update(struct ccdrbg_state * ctx,unsigned ndata,...)93 update(struct ccdrbg_state *ctx, unsigned ndata, ...)
94 {
95 struct ccdrbg_nisthmac_state *drbg_ctx = (struct ccdrbg_nisthmac_state *)ctx;
96 const struct ccdigest_info *info = drbg_ctx->custom->di;
97 size_t outlen = info->output_size;
98 size_t data_nbytes = 0;
99 va_list args;
100
101 cchmac_di_decl(info, hmac_ctx);
102
103 for (uint8_t b = 0; b < 2; b += 1) {
104 cchmac_init(info, hmac_ctx, outlen, drbg_ctx->key);
105
106 cchmac_update(info, hmac_ctx, outlen, drbg_ctx->V);
107
108 cchmac_update(info, hmac_ctx, sizeof(b), &b);
109
110 va_start(args, ndata);
111
112 for (unsigned i = 0; i < ndata; i += 1) {
113 size_t nbytes = va_arg(args, size_t);
114 const void *buf = va_arg(args, const void *);
115
116 cchmac_update(info, hmac_ctx, nbytes, buf);
117
118 data_nbytes += nbytes;
119 }
120
121 va_end(args);
122
123 cchmac_final(info, hmac_ctx, drbg_ctx->key);
124
125 cchmac(info, outlen, drbg_ctx->key, outlen, drbg_ctx->V, drbg_ctx->V);
126
127 if (data_nbytes == 0) {
128 break;
129 }
130 }
131
132 cchmac_di_clear(info, hmac_ctx);
133 }
134
135 static bool
entropy_isvalid(size_t entropy_nbytes,const struct ccdigest_info * info)136 entropy_isvalid(size_t entropy_nbytes, const struct ccdigest_info *info)
137 {
138 return (entropy_nbytes <= CCDRBG_MAX_ENTROPY_SIZE) && (entropy_nbytes >= MIN_REQ_ENTROPY(info));
139 }
140
141 // See NIST SP 800-90A, Rev. 1, 9.1 and 10.1.2.3
142 static int
init(const struct ccdrbg_info * info,struct ccdrbg_state * ctx,size_t entropy_nbytes,const void * entropy,size_t nonce_nbytes,const void * nonce,size_t ps_nbytes,const void * ps)143 init(const struct ccdrbg_info *info,
144 struct ccdrbg_state *ctx,
145 size_t entropy_nbytes,
146 const void *entropy,
147 size_t nonce_nbytes,
148 const void *nonce,
149 size_t ps_nbytes,
150 const void *ps)
151 {
152 struct ccdrbg_nisthmac_state *drbg_ctx = (struct ccdrbg_nisthmac_state *)ctx;
153 drbg_ctx->custom = info->custom;
154 const struct ccdigest_info *digest_info = drbg_ctx->custom->di;
155 size_t outlen = digest_info->output_size;
156
157 int status = CCDRBG_STATUS_PARAM_ERROR;
158 cc_require(outlen <= DRBG_HMAC_MAX_OUTPUT_SIZE, out);
159 cc_require(entropy_isvalid(entropy_nbytes, digest_info), out);
160 cc_require(ps_nbytes <= CCDRBG_MAX_PSINPUT_SIZE, out);
161
162 status = CCDRBG_STATUS_OK;
163
164 cc_memset(drbg_ctx->key, 0, outlen);
165 cc_memset(drbg_ctx->V, 1, outlen);
166
167 update(ctx, 3, entropy_nbytes, entropy, nonce_nbytes, nonce, ps_nbytes, ps);
168
169 drbg_ctx->reseed_counter = 1;
170
171 out:
172 return status;
173 }
174
175 static bool
add_isvalid(size_t add_nbytes)176 add_isvalid(size_t add_nbytes)
177 {
178 return add_nbytes <= CCDRBG_MAX_ADDITIONALINPUT_SIZE;
179 }
180
181 // See NIST SP 800-90A, Rev. 1, 9.2 and 10.1.2.4
182 static int
reseed(struct ccdrbg_state * ctx,size_t entropy_nbytes,const void * entropy,size_t add_nbytes,const void * add)183 reseed(struct ccdrbg_state *ctx, size_t entropy_nbytes, const void *entropy, size_t add_nbytes, const void *add)
184 {
185 struct ccdrbg_nisthmac_state *drbg_ctx = (struct ccdrbg_nisthmac_state *)ctx;
186 const struct ccdigest_info *digest_info = drbg_ctx->custom->di;
187
188 int status = CCDRBG_STATUS_PARAM_ERROR;
189 cc_require(entropy_isvalid(entropy_nbytes, digest_info), out);
190 cc_require(add_isvalid(add_nbytes), out);
191
192 status = CCDRBG_STATUS_OK;
193
194 update(ctx, 2, entropy_nbytes, entropy, add_nbytes, add);
195
196 drbg_ctx->reseed_counter = 1;
197
198 out:
199 return status;
200 }
201
202 static bool
must_reseed(const struct ccdrbg_state * ctx)203 must_reseed(const struct ccdrbg_state *ctx)
204 {
205 const struct ccdrbg_nisthmac_state *drbg_ctx = (const struct ccdrbg_nisthmac_state *)ctx;
206
207 return drbg_ctx->custom->strictFIPS &&
208 (drbg_ctx->reseed_counter > CCDRBG_RESEED_INTERVAL);
209 }
210
211 // See NIST SP 800-90A, Rev. 1, 9.3 and 10.1.2.5
212 static int
generate(struct ccdrbg_state * ctx,size_t out_nbytes,void * out,size_t add_nbytes,const void * add)213 generate(struct ccdrbg_state *ctx, size_t out_nbytes, void *out, size_t add_nbytes, const void *add)
214 {
215 struct ccdrbg_nisthmac_state *drbg_ctx = (struct ccdrbg_nisthmac_state *)ctx;
216 const struct ccdigest_info *info = drbg_ctx->custom->di;
217 size_t outlen = info->output_size;
218
219 int status = CCDRBG_STATUS_PARAM_ERROR;
220 cc_require(out_nbytes <= CCDRBG_MAX_REQUEST_SIZE, out);
221 cc_require(add_isvalid(add_nbytes), out);
222
223 status = CCDRBG_STATUS_NEED_RESEED;
224 cc_require(!must_reseed(ctx), out);
225
226 status = CCDRBG_STATUS_OK;
227
228 if (add_nbytes > 0) {
229 update(ctx, 1, add_nbytes, add);
230 }
231
232 uint8_t *out_bytes = out;
233 uint8_t Vprev[DRBG_HMAC_MAX_OUTPUT_SIZE];
234
235 while (out_nbytes > 0) {
236 cc_memcpy(Vprev, drbg_ctx->V, outlen);
237 cchmac(info, outlen, drbg_ctx->key, outlen, drbg_ctx->V, drbg_ctx->V);
238
239 // See FIPS 140-2, 4.9.2 Conditional Tests
240 if (cc_cmp_safe(outlen, Vprev, drbg_ctx->V) == 0) {
241 done(ctx);
242 status = CCDRBG_STATUS_ABORT;
243 cc_try_abort(NULL);
244 goto out;
245 }
246
247 size_t n = CC_MIN(out_nbytes, outlen);
248 cc_memcpy(out_bytes, drbg_ctx->V, n);
249
250 out_bytes += n;
251 out_nbytes -= n;
252 }
253
254 update(ctx, 1, add_nbytes, add);
255
256 drbg_ctx->reseed_counter += 1;
257
258 out:
259 cc_clear(outlen, Vprev);
260 return status;
261 }
262
263 void
ccdrbg_factory_nisthmac(struct ccdrbg_info * info,const struct ccdrbg_nisthmac_custom * custom)264 ccdrbg_factory_nisthmac(struct ccdrbg_info *info, const struct ccdrbg_nisthmac_custom *custom)
265 {
266 CC_ENSURE_DIT_ENABLED
267
268 info->size = sizeof(struct ccdrbg_nisthmac_state) + sizeof(struct ccdrbg_nisthmac_custom);
269 info->init = init;
270 info->generate = generate;
271 info->reseed = reseed;
272 info->done = done;
273 info->custom = custom;
274 info->must_reseed = must_reseed;
275 };
276