1 /*
2 * Copyright 2020-2022 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 /*
11 * RSA low level APIs are deprecated for public use, but still ok for
12 * internal use.
13 */
14 #include "internal/deprecated.h"
15 #include "internal/nelem.h"
16
17 #include <openssl/crypto.h>
18 #include <openssl/evp.h>
19 #include <openssl/core_dispatch.h>
20 #include <openssl/core_names.h>
21 #include <openssl/rsa.h>
22 #include <openssl/params.h>
23 #include <openssl/err.h>
24 #include "crypto/rsa.h"
25 #include <openssl/proverr.h>
26 #include "prov/provider_ctx.h"
27 #include "prov/implementations.h"
28 #include "prov/securitycheck.h"
29
30 static OSSL_FUNC_kem_newctx_fn rsakem_newctx;
31 static OSSL_FUNC_kem_encapsulate_init_fn rsakem_encapsulate_init;
32 static OSSL_FUNC_kem_encapsulate_fn rsakem_generate;
33 static OSSL_FUNC_kem_decapsulate_init_fn rsakem_decapsulate_init;
34 static OSSL_FUNC_kem_decapsulate_fn rsakem_recover;
35 static OSSL_FUNC_kem_freectx_fn rsakem_freectx;
36 static OSSL_FUNC_kem_dupctx_fn rsakem_dupctx;
37 static OSSL_FUNC_kem_get_ctx_params_fn rsakem_get_ctx_params;
38 static OSSL_FUNC_kem_gettable_ctx_params_fn rsakem_gettable_ctx_params;
39 static OSSL_FUNC_kem_set_ctx_params_fn rsakem_set_ctx_params;
40 static OSSL_FUNC_kem_settable_ctx_params_fn rsakem_settable_ctx_params;
41
42 /*
43 * Only the KEM for RSASVE as defined in SP800-56b r2 is implemented
44 * currently.
45 */
46 #define KEM_OP_UNDEFINED -1
47 #define KEM_OP_RSASVE 0
48
49 /*
50 * What's passed as an actual key is defined by the KEYMGMT interface.
51 * We happen to know that our KEYMGMT simply passes RSA structures, so
52 * we use that here too.
53 */
54 typedef struct {
55 OSSL_LIB_CTX *libctx;
56 RSA *rsa;
57 int op;
58 } PROV_RSA_CTX;
59
60 static const OSSL_ITEM rsakem_opname_id_map[] = {
61 { KEM_OP_RSASVE, OSSL_KEM_PARAM_OPERATION_RSASVE },
62 };
63
name2id(const char * name,const OSSL_ITEM * map,size_t sz)64 static int name2id(const char *name, const OSSL_ITEM *map, size_t sz)
65 {
66 size_t i;
67
68 if (name == NULL)
69 return -1;
70
71 for (i = 0; i < sz; ++i) {
72 if (OPENSSL_strcasecmp(map[i].ptr, name) == 0)
73 return map[i].id;
74 }
75 return -1;
76 }
77
rsakem_opname2id(const char * name)78 static int rsakem_opname2id(const char *name)
79 {
80 return name2id(name, rsakem_opname_id_map, OSSL_NELEM(rsakem_opname_id_map));
81 }
82
rsakem_newctx(void * provctx)83 static void *rsakem_newctx(void *provctx)
84 {
85 PROV_RSA_CTX *prsactx = OPENSSL_zalloc(sizeof(PROV_RSA_CTX));
86
87 if (prsactx == NULL)
88 return NULL;
89 prsactx->libctx = PROV_LIBCTX_OF(provctx);
90 prsactx->op = KEM_OP_UNDEFINED;
91
92 return prsactx;
93 }
94
rsakem_freectx(void * vprsactx)95 static void rsakem_freectx(void *vprsactx)
96 {
97 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
98
99 RSA_free(prsactx->rsa);
100 OPENSSL_free(prsactx);
101 }
102
rsakem_dupctx(void * vprsactx)103 static void *rsakem_dupctx(void *vprsactx)
104 {
105 PROV_RSA_CTX *srcctx = (PROV_RSA_CTX *)vprsactx;
106 PROV_RSA_CTX *dstctx;
107
108 dstctx = OPENSSL_zalloc(sizeof(*srcctx));
109 if (dstctx == NULL)
110 return NULL;
111
112 *dstctx = *srcctx;
113 if (dstctx->rsa != NULL && !RSA_up_ref(dstctx->rsa)) {
114 OPENSSL_free(dstctx);
115 return NULL;
116 }
117 return dstctx;
118 }
119
rsakem_init(void * vprsactx,void * vrsa,const OSSL_PARAM params[],int operation)120 static int rsakem_init(void *vprsactx, void *vrsa,
121 const OSSL_PARAM params[], int operation)
122 {
123 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
124
125 if (prsactx == NULL || vrsa == NULL)
126 return 0;
127
128 if (!ossl_rsa_check_key(prsactx->libctx, vrsa, operation))
129 return 0;
130
131 if (!RSA_up_ref(vrsa))
132 return 0;
133 RSA_free(prsactx->rsa);
134 prsactx->rsa = vrsa;
135
136 return rsakem_set_ctx_params(prsactx, params);
137 }
138
rsakem_encapsulate_init(void * vprsactx,void * vrsa,const OSSL_PARAM params[])139 static int rsakem_encapsulate_init(void *vprsactx, void *vrsa,
140 const OSSL_PARAM params[])
141 {
142 return rsakem_init(vprsactx, vrsa, params, EVP_PKEY_OP_ENCAPSULATE);
143 }
144
rsakem_decapsulate_init(void * vprsactx,void * vrsa,const OSSL_PARAM params[])145 static int rsakem_decapsulate_init(void *vprsactx, void *vrsa,
146 const OSSL_PARAM params[])
147 {
148 return rsakem_init(vprsactx, vrsa, params, EVP_PKEY_OP_DECAPSULATE);
149 }
150
rsakem_get_ctx_params(void * vprsactx,OSSL_PARAM * params)151 static int rsakem_get_ctx_params(void *vprsactx, OSSL_PARAM *params)
152 {
153 PROV_RSA_CTX *ctx = (PROV_RSA_CTX *)vprsactx;
154
155 return ctx != NULL;
156 }
157
158 static const OSSL_PARAM known_gettable_rsakem_ctx_params[] = {
159 OSSL_PARAM_END
160 };
161
rsakem_gettable_ctx_params(ossl_unused void * vprsactx,ossl_unused void * provctx)162 static const OSSL_PARAM *rsakem_gettable_ctx_params(ossl_unused void *vprsactx,
163 ossl_unused void *provctx)
164 {
165 return known_gettable_rsakem_ctx_params;
166 }
167
rsakem_set_ctx_params(void * vprsactx,const OSSL_PARAM params[])168 static int rsakem_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
169 {
170 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
171 const OSSL_PARAM *p;
172 int op;
173
174 if (prsactx == NULL)
175 return 0;
176 if (params == NULL)
177 return 1;
178
179
180 p = OSSL_PARAM_locate_const(params, OSSL_KEM_PARAM_OPERATION);
181 if (p != NULL) {
182 if (p->data_type != OSSL_PARAM_UTF8_STRING)
183 return 0;
184 op = rsakem_opname2id(p->data);
185 if (op < 0)
186 return 0;
187 prsactx->op = op;
188 }
189 return 1;
190 }
191
192 static const OSSL_PARAM known_settable_rsakem_ctx_params[] = {
193 OSSL_PARAM_utf8_string(OSSL_KEM_PARAM_OPERATION, NULL, 0),
194 OSSL_PARAM_END
195 };
196
rsakem_settable_ctx_params(ossl_unused void * vprsactx,ossl_unused void * provctx)197 static const OSSL_PARAM *rsakem_settable_ctx_params(ossl_unused void *vprsactx,
198 ossl_unused void *provctx)
199 {
200 return known_settable_rsakem_ctx_params;
201 }
202
203 /*
204 * NIST.SP.800-56Br2
205 * 7.2.1.2 RSASVE Generate Operation (RSASVE.GENERATE).
206 *
207 * Generate a random in the range 1 < z < (n – 1)
208 */
rsasve_gen_rand_bytes(RSA * rsa_pub,unsigned char * out,int outlen)209 static int rsasve_gen_rand_bytes(RSA *rsa_pub,
210 unsigned char *out, int outlen)
211 {
212 int ret = 0;
213 BN_CTX *bnctx;
214 BIGNUM *z, *nminus3;
215
216 bnctx = BN_CTX_secure_new_ex(ossl_rsa_get0_libctx(rsa_pub));
217 if (bnctx == NULL)
218 return 0;
219
220 /*
221 * Generate a random in the range 1 < z < (n – 1).
222 * Since BN_priv_rand_range_ex() returns a value in range 0 <= r < max
223 * We can achieve this by adding 2.. but then we need to subtract 3 from
224 * the upper bound i.e: 2 + (0 <= r < (n - 3))
225 */
226 BN_CTX_start(bnctx);
227 nminus3 = BN_CTX_get(bnctx);
228 z = BN_CTX_get(bnctx);
229 ret = (z != NULL
230 && (BN_copy(nminus3, RSA_get0_n(rsa_pub)) != NULL)
231 && BN_sub_word(nminus3, 3)
232 && BN_priv_rand_range_ex(z, nminus3, 0, bnctx)
233 && BN_add_word(z, 2)
234 && (BN_bn2binpad(z, out, outlen) == outlen));
235 BN_CTX_end(bnctx);
236 BN_CTX_free(bnctx);
237 return ret;
238 }
239
240 /*
241 * NIST.SP.800-56Br2
242 * 7.2.1.2 RSASVE Generate Operation (RSASVE.GENERATE).
243 */
rsasve_generate(PROV_RSA_CTX * prsactx,unsigned char * out,size_t * outlen,unsigned char * secret,size_t * secretlen)244 static int rsasve_generate(PROV_RSA_CTX *prsactx,
245 unsigned char *out, size_t *outlen,
246 unsigned char *secret, size_t *secretlen)
247 {
248 int ret;
249 size_t nlen;
250
251 /* Step (1): nlen = Ceil(len(n)/8) */
252 nlen = RSA_size(prsactx->rsa);
253
254 if (out == NULL) {
255 if (nlen == 0) {
256 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY);
257 return 0;
258 }
259 if (outlen == NULL && secretlen == NULL)
260 return 0;
261 if (outlen != NULL)
262 *outlen = nlen;
263 if (secretlen != NULL)
264 *secretlen = nlen;
265 return 1;
266 }
267 /*
268 * Step (2): Generate a random byte string z of nlen bytes where
269 * 1 < z < n - 1
270 */
271 if (!rsasve_gen_rand_bytes(prsactx->rsa, secret, nlen))
272 return 0;
273
274 /* Step(3): out = RSAEP((n,e), z) */
275 ret = RSA_public_encrypt(nlen, secret, out, prsactx->rsa, RSA_NO_PADDING);
276 if (ret) {
277 ret = 1;
278 if (outlen != NULL)
279 *outlen = nlen;
280 if (secretlen != NULL)
281 *secretlen = nlen;
282 } else {
283 OPENSSL_cleanse(secret, nlen);
284 }
285 return ret;
286 }
287
288 /*
289 * NIST.SP.800-56Br2
290 * 7.2.1.3 RSASVE Recovery Operation (RSASVE.RECOVER).
291 */
rsasve_recover(PROV_RSA_CTX * prsactx,unsigned char * out,size_t * outlen,const unsigned char * in,size_t inlen)292 static int rsasve_recover(PROV_RSA_CTX *prsactx,
293 unsigned char *out, size_t *outlen,
294 const unsigned char *in, size_t inlen)
295 {
296 size_t nlen;
297
298 /* Step (1): get the byte length of n */
299 nlen = RSA_size(prsactx->rsa);
300
301 if (out == NULL) {
302 if (nlen == 0) {
303 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY);
304 return 0;
305 }
306 *outlen = nlen;
307 return 1;
308 }
309
310 /* Step (2): check the input ciphertext 'inlen' matches the nlen */
311 if (inlen != nlen) {
312 ERR_raise(ERR_LIB_PROV, PROV_R_BAD_LENGTH);
313 return 0;
314 }
315 /* Step (3): out = RSADP((n,d), in) */
316 return (RSA_private_decrypt(inlen, in, out, prsactx->rsa, RSA_NO_PADDING) > 0);
317 }
318
rsakem_generate(void * vprsactx,unsigned char * out,size_t * outlen,unsigned char * secret,size_t * secretlen)319 static int rsakem_generate(void *vprsactx, unsigned char *out, size_t *outlen,
320 unsigned char *secret, size_t *secretlen)
321 {
322 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
323
324 switch (prsactx->op) {
325 case KEM_OP_RSASVE:
326 return rsasve_generate(prsactx, out, outlen, secret, secretlen);
327 default:
328 return -2;
329 }
330 }
331
rsakem_recover(void * vprsactx,unsigned char * out,size_t * outlen,const unsigned char * in,size_t inlen)332 static int rsakem_recover(void *vprsactx, unsigned char *out, size_t *outlen,
333 const unsigned char *in, size_t inlen)
334 {
335 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
336
337 switch (prsactx->op) {
338 case KEM_OP_RSASVE:
339 return rsasve_recover(prsactx, out, outlen, in, inlen);
340 default:
341 return -2;
342 }
343 }
344
345 const OSSL_DISPATCH ossl_rsa_asym_kem_functions[] = {
346 { OSSL_FUNC_KEM_NEWCTX, (void (*)(void))rsakem_newctx },
347 { OSSL_FUNC_KEM_ENCAPSULATE_INIT,
348 (void (*)(void))rsakem_encapsulate_init },
349 { OSSL_FUNC_KEM_ENCAPSULATE, (void (*)(void))rsakem_generate },
350 { OSSL_FUNC_KEM_DECAPSULATE_INIT,
351 (void (*)(void))rsakem_decapsulate_init },
352 { OSSL_FUNC_KEM_DECAPSULATE, (void (*)(void))rsakem_recover },
353 { OSSL_FUNC_KEM_FREECTX, (void (*)(void))rsakem_freectx },
354 { OSSL_FUNC_KEM_DUPCTX, (void (*)(void))rsakem_dupctx },
355 { OSSL_FUNC_KEM_GET_CTX_PARAMS,
356 (void (*)(void))rsakem_get_ctx_params },
357 { OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS,
358 (void (*)(void))rsakem_gettable_ctx_params },
359 { OSSL_FUNC_KEM_SET_CTX_PARAMS,
360 (void (*)(void))rsakem_set_ctx_params },
361 { OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS,
362 (void (*)(void))rsakem_settable_ctx_params },
363 { 0, NULL }
364 };
365