providers/implementations/kem/rsa_kem.c

   1 /*
   2  * Copyright 2020-2021 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
  16 #include "e_os.h"  /* strcasecmp */
  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
  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 (strcasecmp(map[i].ptr, name) == 0)
  73             return map[i].id;
  74     }
  75     return -1;
  76 }
  77
  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
  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
  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
 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
 120 static int rsakem_init(void *vprsactx, void *vrsa, int operation)
 121 {
 122     PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
 123
 124     if (prsactx == NULL || vrsa == NULL || !RSA_up_ref(vrsa))
 125         return 0;
 126     RSA_free(prsactx->rsa);
 127     prsactx->rsa = vrsa;
 128
 129     if (!ossl_rsa_check_key(vrsa, operation == EVP_PKEY_OP_ENCAPSULATE)) {
 130         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
 131         return 0;
 132     }
 133     return 1;
 134 }
 135
 136 static int rsakem_encapsulate_init(void *vprsactx, void *vrsa)
 137 {
 138     return rsakem_init(vprsactx, vrsa, EVP_PKEY_OP_ENCAPSULATE);
 139 }
 140
 141 static int rsakem_decapsulate_init(void *vprsactx, void *vrsa)
 142 {
 143     return rsakem_init(vprsactx, vrsa, EVP_PKEY_OP_DECAPSULATE);
 144 }
 145
 146 static int rsakem_get_ctx_params(void *vprsactx, OSSL_PARAM *params)
 147 {
 148     PROV_RSA_CTX *ctx = (PROV_RSA_CTX *)vprsactx;
 149
 150     if (ctx == NULL || params == NULL)
 151         return 0;
 152     return 1;
 153 }
 154
 155 static const OSSL_PARAM known_gettable_rsakem_ctx_params[] = {
 156     OSSL_PARAM_END
 157 };
 158
 159 static const OSSL_PARAM *rsakem_gettable_ctx_params(ossl_unused void *vprsactx,
 160                                                     ossl_unused void *provctx)
 161 {
 162     return known_gettable_rsakem_ctx_params;
 163 }
 164
 165 static int rsakem_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
 166 {
 167     PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
 168     const OSSL_PARAM *p;
 169     int op;
 170
 171     if (prsactx == NULL || params == NULL)
 172         return 0;
 173
 174     p = OSSL_PARAM_locate_const(params, OSSL_KEM_PARAM_OPERATION);
 175     if (p != NULL) {
 176         if (p->data_type != OSSL_PARAM_UTF8_STRING)
 177             return 0;
 178         op = rsakem_opname2id(p->data);
 179         if (op < 0)
 180             return 0;
 181         prsactx->op = op;
 182     }
 183     return 1;
 184 }
 185
 186 static const OSSL_PARAM known_settable_rsakem_ctx_params[] = {
 187     OSSL_PARAM_utf8_string(OSSL_KEM_PARAM_OPERATION, NULL, 0),
 188     OSSL_PARAM_END
 189 };
 190
 191 static const OSSL_PARAM *rsakem_settable_ctx_params(ossl_unused void *vprsactx,
 192                                                     ossl_unused void *provctx)
 193 {
 194     return known_settable_rsakem_ctx_params;
 195 }
 196
 197 /*
 198  * NIST.SP.800-56Br2
 199  * 7.2.1.2 RSASVE Generate Operation (RSASVE.GENERATE).
 200  *
 201  * Generate a random in the range 1 < z < (n – 1)
 202  */
 203 static int rsasve_gen_rand_bytes(RSA *rsa_pub,
 204                                  unsigned char *out, int outlen)
 205 {
 206     int ret = 0;
 207     BN_CTX *bnctx;
 208     BIGNUM *z, *nminus3;
 209
 210     bnctx = BN_CTX_secure_new_ex(ossl_rsa_get0_libctx(rsa_pub));
 211     if (bnctx == NULL)
 212         return 0;
 213
 214     /*
 215      * Generate a random in the range 1 < z < (n – 1).
 216      * Since BN_priv_rand_range_ex() returns a value in range 0 <= r < max
 217      * We can achieve this by adding 2.. but then we need to subtract 3 from
 218      * the upper bound i.e: 2 + (0 <= r < (n - 3))
 219      */
 220     BN_CTX_start(bnctx);
 221     nminus3 = BN_CTX_get(bnctx);
 222     z = BN_CTX_get(bnctx);
 223     ret = (z != NULL
 224            && (BN_copy(nminus3, RSA_get0_n(rsa_pub)) != NULL)
 225            && BN_sub_word(nminus3, 3)
 226            && BN_priv_rand_range_ex(z, nminus3, bnctx)
 227            && BN_add_word(z, 2)
 228            && (BN_bn2binpad(z, out, outlen) == outlen));
 229     BN_CTX_end(bnctx);
 230     BN_CTX_free(bnctx);
 231     return ret;
 232 }
 233
 234 /*
 235  * NIST.SP.800-56Br2
 236  * 7.2.1.2 RSASVE Generate Operation (RSASVE.GENERATE).
 237  */
 238 static int rsasve_generate(PROV_RSA_CTX *prsactx,
 239                            unsigned char *out, size_t *outlen,
 240                            unsigned char *secret, size_t *secretlen)
 241 {
 242     int ret;
 243     size_t nlen;
 244
 245     /* Step (1): nlen = Ceil(len(n)/8) */
 246     nlen = RSA_size(prsactx->rsa);
 247
 248     if (out == NULL) {
 249         if (nlen == 0) {
 250             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY);
 251             return 0;
 252         }
 253         if (outlen == NULL && secretlen == NULL)
 254             return 0;
 255         if (outlen != NULL)
 256             *outlen = nlen;
 257         if (secretlen != NULL)
 258             *secretlen = nlen;
 259         return 1;
 260     }
 261     /*
 262      * Step (2): Generate a random byte string z of nlen bytes where
 263      *            1 < z < n - 1
 264      */
 265     if (!rsasve_gen_rand_bytes(prsactx->rsa, secret, nlen))
 266         return 0;
 267
 268     /* Step(3): out = RSAEP((n,e), z) */
 269     ret = RSA_public_encrypt(nlen, secret, out, prsactx->rsa, RSA_NO_PADDING);
 270     if (ret) {
 271         ret = 1;
 272         if (outlen != NULL)
 273             *outlen = nlen;
 274         if (secretlen != NULL)
 275             *secretlen = nlen;
 276     } else {
 277         OPENSSL_cleanse(secret, nlen);
 278     }
 279     return ret;
 280 }
 281
 282 /*
 283  * NIST.SP.800-56Br2
 284  * 7.2.1.3 RSASVE Recovery Operation (RSASVE.RECOVER).
 285  */
 286 static int rsasve_recover(PROV_RSA_CTX *prsactx,
 287                           unsigned char *out, size_t *outlen,
 288                           const unsigned char *in, size_t inlen)
 289 {
 290     size_t nlen;
 291
 292     /* Step (1): get the byte length of n */
 293     nlen = RSA_size(prsactx->rsa);
 294
 295     if (out == NULL) {
 296         if (nlen == 0) {
 297             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY);
 298             return 0;
 299         }
 300         *outlen = nlen;
 301         return 1;
 302     }
 303
 304     /* Step (2): check the input ciphertext 'inlen' matches the nlen */
 305     if (inlen != nlen) {
 306         ERR_raise(ERR_LIB_PROV, PROV_R_BAD_LENGTH);
 307         return 0;
 308     }
 309     /* Step (3): out = RSADP((n,d), in) */
 310     return (RSA_private_decrypt(inlen, in, out, prsactx->rsa, RSA_NO_PADDING) > 0);
 311 }
 312
 313 static int rsakem_generate(void *vprsactx, unsigned char *out, size_t *outlen,
 314                            unsigned char *secret, size_t *secretlen)
 315 {
 316     PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
 317
 318     switch (prsactx->op) {
 319         case KEM_OP_RSASVE:
 320             return rsasve_generate(prsactx, out, outlen, secret, secretlen);
 321         default:
 322             return -2;
 323     }
 324 }
 325
 326 static int rsakem_recover(void *vprsactx, unsigned char *out, size_t *outlen,
 327                           const unsigned char *in, size_t inlen)
 328 {
 329     PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
 330
 331     switch (prsactx->op) {
 332         case KEM_OP_RSASVE:
 333             return rsasve_recover(prsactx, out, outlen, in, inlen);
 334         default:
 335             return -2;
 336     }
 337 }
 338
 339 const OSSL_DISPATCH ossl_rsa_asym_kem_functions[] = {
 340     { OSSL_FUNC_KEM_NEWCTX, (void (*)(void))rsakem_newctx },
 341     { OSSL_FUNC_KEM_ENCAPSULATE_INIT,
 342       (void (*)(void))rsakem_encapsulate_init },
 343     { OSSL_FUNC_KEM_ENCAPSULATE, (void (*)(void))rsakem_generate },
 344     { OSSL_FUNC_KEM_DECAPSULATE_INIT,
 345       (void (*)(void))rsakem_decapsulate_init },
 346     { OSSL_FUNC_KEM_DECAPSULATE, (void (*)(void))rsakem_recover },
 347     { OSSL_FUNC_KEM_FREECTX, (void (*)(void))rsakem_freectx },
 348     { OSSL_FUNC_KEM_DUPCTX, (void (*)(void))rsakem_dupctx },
 349     { OSSL_FUNC_KEM_GET_CTX_PARAMS,
 350       (void (*)(void))rsakem_get_ctx_params },
 351     { OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS,
 352       (void (*)(void))rsakem_gettable_ctx_params },
 353     { OSSL_FUNC_KEM_SET_CTX_PARAMS,
 354       (void (*)(void))rsakem_set_ctx_params },
 355     { OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS,
 356       (void (*)(void))rsakem_settable_ctx_params },
 357     { 0, NULL }
 358 };