1 /* 2 * Copyright 2020-2025 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 #include <openssl/crypto.h> 17 #include <openssl/evp.h> 18 #include <openssl/core_dispatch.h> 19 #include <openssl/core_names.h> 20 #include <openssl/rsa.h> 21 #include <openssl/params.h> 22 #include <openssl/err.h> 23 #include <openssl/proverr.h> 24 #include "crypto/rsa.h" 25 #include "prov/provider_ctx.h" 26 #include "prov/providercommon.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 OSSL_FIPS_IND_DECLARE 59 } PROV_RSA_CTX; 60 61 static const OSSL_ITEM rsakem_opname_id_map[] = { 62 { KEM_OP_RSASVE, OSSL_KEM_PARAM_OPERATION_RSASVE }, 63 }; 64 65 static int name2id(const char *name, const OSSL_ITEM *map, size_t sz) 66 { 67 size_t i; 68 69 if (name == NULL) 70 return -1; 71 72 for (i = 0; i < sz; ++i) { 73 if (OPENSSL_strcasecmp(map[i].ptr, name) == 0) 74 return map[i].id; 75 } 76 return -1; 77 } 78 79 static int rsakem_opname2id(const char *name) 80 { 81 return name2id(name, rsakem_opname_id_map, OSSL_NELEM(rsakem_opname_id_map)); 82 } 83 84 static void *rsakem_newctx(void *provctx) 85 { 86 PROV_RSA_CTX *prsactx; 87 88 if (!ossl_prov_is_running()) 89 return NULL; 90 91 prsactx = OPENSSL_zalloc(sizeof(PROV_RSA_CTX)); 92 if (prsactx == NULL) 93 return NULL; 94 prsactx->libctx = PROV_LIBCTX_OF(provctx); 95 prsactx->op = KEM_OP_RSASVE; 96 OSSL_FIPS_IND_INIT(prsactx) 97 98 return prsactx; 99 } 100 101 static void rsakem_freectx(void *vprsactx) 102 { 103 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx; 104 105 RSA_free(prsactx->rsa); 106 OPENSSL_free(prsactx); 107 } 108 109 static void *rsakem_dupctx(void *vprsactx) 110 { 111 PROV_RSA_CTX *srcctx = (PROV_RSA_CTX *)vprsactx; 112 PROV_RSA_CTX *dstctx; 113 114 if (!ossl_prov_is_running()) 115 return NULL; 116 117 dstctx = OPENSSL_zalloc(sizeof(*srcctx)); 118 if (dstctx == NULL) 119 return NULL; 120 121 *dstctx = *srcctx; 122 if (dstctx->rsa != NULL && !RSA_up_ref(dstctx->rsa)) { 123 OPENSSL_free(dstctx); 124 return NULL; 125 } 126 return dstctx; 127 } 128 129 static int rsakem_init(void *vprsactx, void *vrsa, 130 const OSSL_PARAM params[], int operation, 131 const char *desc) 132 { 133 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx; 134 int protect = 0; 135 136 if (!ossl_prov_is_running()) 137 return 0; 138 139 if (prsactx == NULL || vrsa == NULL) 140 return 0; 141 142 if (!ossl_rsa_key_op_get_protect(vrsa, operation, &protect)) 143 return 0; 144 if (!RSA_up_ref(vrsa)) 145 return 0; 146 RSA_free(prsactx->rsa); 147 prsactx->rsa = vrsa; 148 149 OSSL_FIPS_IND_SET_APPROVED(prsactx) 150 if (!rsakem_set_ctx_params(prsactx, params)) 151 return 0; 152 #ifdef FIPS_MODULE 153 if (!ossl_fips_ind_rsa_key_check(OSSL_FIPS_IND_GET(prsactx), 154 OSSL_FIPS_IND_SETTABLE0, prsactx->libctx, 155 prsactx->rsa, desc, protect)) 156 return 0; 157 #endif 158 return 1; 159 } 160 161 static int rsakem_encapsulate_init(void *vprsactx, void *vrsa, 162 const OSSL_PARAM params[]) 163 { 164 return rsakem_init(vprsactx, vrsa, params, EVP_PKEY_OP_ENCAPSULATE, 165 "RSA Encapsulate Init"); 166 } 167 168 static int rsakem_decapsulate_init(void *vprsactx, void *vrsa, 169 const OSSL_PARAM params[]) 170 { 171 return rsakem_init(vprsactx, vrsa, params, EVP_PKEY_OP_DECAPSULATE, 172 "RSA Decapsulate Init"); 173 } 174 175 static int rsakem_get_ctx_params(void *vprsactx, OSSL_PARAM *params) 176 { 177 PROV_RSA_CTX *ctx = (PROV_RSA_CTX *)vprsactx; 178 179 if (ctx == NULL) 180 return 0; 181 182 if (!OSSL_FIPS_IND_GET_CTX_PARAM(ctx, params)) 183 return 0; 184 return 1; 185 } 186 187 static const OSSL_PARAM known_gettable_rsakem_ctx_params[] = { 188 OSSL_FIPS_IND_GETTABLE_CTX_PARAM() 189 OSSL_PARAM_END 190 }; 191 192 static const OSSL_PARAM *rsakem_gettable_ctx_params(ossl_unused void *vprsactx, 193 ossl_unused void *provctx) 194 { 195 return known_gettable_rsakem_ctx_params; 196 } 197 198 static int rsakem_set_ctx_params(void *vprsactx, const OSSL_PARAM params[]) 199 { 200 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx; 201 const OSSL_PARAM *p; 202 int op; 203 204 if (prsactx == NULL) 205 return 0; 206 if (ossl_param_is_empty(params)) 207 return 1; 208 209 if (!OSSL_FIPS_IND_SET_CTX_PARAM(prsactx, OSSL_FIPS_IND_SETTABLE0, params, 210 OSSL_KEM_PARAM_FIPS_KEY_CHECK)) 211 return 0; 212 p = OSSL_PARAM_locate_const(params, OSSL_KEM_PARAM_OPERATION); 213 if (p != NULL) { 214 if (p->data_type != OSSL_PARAM_UTF8_STRING) 215 return 0; 216 op = rsakem_opname2id(p->data); 217 if (op < 0) 218 return 0; 219 prsactx->op = op; 220 } 221 return 1; 222 } 223 224 static const OSSL_PARAM known_settable_rsakem_ctx_params[] = { 225 OSSL_PARAM_utf8_string(OSSL_KEM_PARAM_OPERATION, NULL, 0), 226 OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_KEM_PARAM_FIPS_KEY_CHECK) 227 OSSL_PARAM_END 228 }; 229 230 static const OSSL_PARAM *rsakem_settable_ctx_params(ossl_unused void *vprsactx, 231 ossl_unused void *provctx) 232 { 233 return known_settable_rsakem_ctx_params; 234 } 235 236 /* 237 * NIST.SP.800-56Br2 238 * 7.2.1.2 RSASVE Generate Operation (RSASVE.GENERATE). 239 * 240 * Generate a random in the range 1 < z < (n – 1) 241 */ 242 static int rsasve_gen_rand_bytes(RSA *rsa_pub, 243 unsigned char *out, int outlen) 244 { 245 int ret = 0; 246 BN_CTX *bnctx; 247 BIGNUM *z, *nminus3; 248 249 bnctx = BN_CTX_secure_new_ex(ossl_rsa_get0_libctx(rsa_pub)); 250 if (bnctx == NULL) 251 return 0; 252 253 /* 254 * Generate a random in the range 1 < z < (n – 1). 255 * Since BN_priv_rand_range_ex() returns a value in range 0 <= r < max 256 * We can achieve this by adding 2.. but then we need to subtract 3 from 257 * the upper bound i.e: 2 + (0 <= r < (n - 3)) 258 */ 259 BN_CTX_start(bnctx); 260 nminus3 = BN_CTX_get(bnctx); 261 z = BN_CTX_get(bnctx); 262 ret = (z != NULL 263 && (BN_copy(nminus3, RSA_get0_n(rsa_pub)) != NULL) 264 && BN_sub_word(nminus3, 3) 265 && BN_priv_rand_range_ex(z, nminus3, 0, bnctx) 266 && BN_add_word(z, 2) 267 && (BN_bn2binpad(z, out, outlen) == outlen)); 268 BN_CTX_end(bnctx); 269 BN_CTX_free(bnctx); 270 return ret; 271 } 272 273 /* 274 * NIST.SP.800-56Br2 275 * 7.2.1.2 RSASVE Generate Operation (RSASVE.GENERATE). 276 */ 277 static int rsasve_generate(PROV_RSA_CTX *prsactx, 278 unsigned char *out, size_t *outlen, 279 unsigned char *secret, size_t *secretlen) 280 { 281 int ret; 282 size_t nlen; 283 284 /* Step (1): nlen = Ceil(len(n)/8) */ 285 nlen = RSA_size(prsactx->rsa); 286 287 if (out == NULL) { 288 if (nlen == 0) { 289 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY); 290 return 0; 291 } 292 if (outlen == NULL && secretlen == NULL) 293 return 0; 294 if (outlen != NULL) 295 *outlen = nlen; 296 if (secretlen != NULL) 297 *secretlen = nlen; 298 return 1; 299 } 300 301 /* 302 * If outlen is specified, then it must report the length 303 * of the out buffer on input so that we can confirm 304 * its size is sufficent for encapsulation 305 */ 306 if (outlen != NULL && *outlen < nlen) { 307 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_OUTPUT_LENGTH); 308 return 0; 309 } 310 311 /* 312 * Step (2): Generate a random byte string z of nlen bytes where 313 * 1 < z < n - 1 314 */ 315 if (!rsasve_gen_rand_bytes(prsactx->rsa, secret, nlen)) 316 return 0; 317 318 /* Step(3): out = RSAEP((n,e), z) */ 319 ret = RSA_public_encrypt(nlen, secret, out, prsactx->rsa, RSA_NO_PADDING); 320 if (ret) { 321 ret = 1; 322 if (outlen != NULL) 323 *outlen = nlen; 324 if (secretlen != NULL) 325 *secretlen = nlen; 326 } else { 327 OPENSSL_cleanse(secret, nlen); 328 } 329 return ret; 330 } 331 332 /** 333 * rsasve_recover - Recovers a secret value from ciphertext using an RSA 334 * private key. Once, recovered, the secret value is considered to be a 335 * shared secret. Algorithm is preformed as per 336 * NIST SP 800-56B Rev 2 337 * 7.2.1.3 RSASVE Recovery Operation (RSASVE.RECOVER). 338 * 339 * This function performs RSA decryption using the private key from the 340 * provided RSA context (`prsactx`). It takes the input ciphertext, decrypts 341 * it, and writes the decrypted message to the output buffer. 342 * 343 * @prsactx: The RSA context containing the private key. 344 * @out: The output buffer to store the decrypted message. 345 * @outlen: On input, the size of the output buffer. On successful 346 * completion, the actual length of the decrypted message. 347 * @in: The input buffer containing the ciphertext to be decrypted. 348 * @inlen: The length of the input ciphertext in bytes. 349 * 350 * Returns 1 on success, or 0 on error. In case of error, appropriate 351 * error messages are raised using the ERR_raise function. 352 */ 353 static int rsasve_recover(PROV_RSA_CTX *prsactx, 354 unsigned char *out, size_t *outlen, 355 const unsigned char *in, size_t inlen) 356 { 357 size_t nlen; 358 int ret; 359 360 /* Step (1): get the byte length of n */ 361 nlen = RSA_size(prsactx->rsa); 362 363 if (out == NULL) { 364 if (nlen == 0) { 365 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY); 366 return 0; 367 } 368 *outlen = nlen; 369 return 1; 370 } 371 372 /* 373 * Step (2): check the input ciphertext 'inlen' matches the nlen 374 * and that outlen is at least nlen bytes 375 */ 376 if (inlen != nlen) { 377 ERR_raise(ERR_LIB_PROV, PROV_R_BAD_LENGTH); 378 return 0; 379 } 380 381 /* 382 * If outlen is specified, then it must report the length 383 * of the out buffer, so that we can confirm that it is of 384 * sufficient size to hold the output of decapsulation 385 */ 386 if (outlen != NULL && *outlen < nlen) { 387 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_OUTPUT_LENGTH); 388 return 0; 389 } 390 391 /* Step (3): out = RSADP((n,d), in) */ 392 ret = RSA_private_decrypt(inlen, in, out, prsactx->rsa, RSA_NO_PADDING); 393 if (ret > 0 && outlen != NULL) 394 *outlen = ret; 395 return ret > 0; 396 } 397 398 static int rsakem_generate(void *vprsactx, unsigned char *out, size_t *outlen, 399 unsigned char *secret, size_t *secretlen) 400 { 401 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx; 402 403 if (!ossl_prov_is_running()) 404 return 0; 405 406 switch (prsactx->op) { 407 case KEM_OP_RSASVE: 408 return rsasve_generate(prsactx, out, outlen, secret, secretlen); 409 default: 410 return -2; 411 } 412 } 413 414 static int rsakem_recover(void *vprsactx, unsigned char *out, size_t *outlen, 415 const unsigned char *in, size_t inlen) 416 { 417 PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx; 418 419 if (!ossl_prov_is_running()) 420 return 0; 421 422 switch (prsactx->op) { 423 case KEM_OP_RSASVE: 424 return rsasve_recover(prsactx, out, outlen, in, inlen); 425 default: 426 return -2; 427 } 428 } 429 430 const OSSL_DISPATCH ossl_rsa_asym_kem_functions[] = { 431 { OSSL_FUNC_KEM_NEWCTX, (void (*)(void))rsakem_newctx }, 432 { OSSL_FUNC_KEM_ENCAPSULATE_INIT, 433 (void (*)(void))rsakem_encapsulate_init }, 434 { OSSL_FUNC_KEM_ENCAPSULATE, (void (*)(void))rsakem_generate }, 435 { OSSL_FUNC_KEM_DECAPSULATE_INIT, 436 (void (*)(void))rsakem_decapsulate_init }, 437 { OSSL_FUNC_KEM_DECAPSULATE, (void (*)(void))rsakem_recover }, 438 { OSSL_FUNC_KEM_FREECTX, (void (*)(void))rsakem_freectx }, 439 { OSSL_FUNC_KEM_DUPCTX, (void (*)(void))rsakem_dupctx }, 440 { OSSL_FUNC_KEM_GET_CTX_PARAMS, 441 (void (*)(void))rsakem_get_ctx_params }, 442 { OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS, 443 (void (*)(void))rsakem_gettable_ctx_params }, 444 { OSSL_FUNC_KEM_SET_CTX_PARAMS, 445 (void (*)(void))rsakem_set_ctx_params }, 446 { OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS, 447 (void (*)(void))rsakem_settable_ctx_params }, 448 OSSL_DISPATCH_END 449 }; 450