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 #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
  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
  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,
 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
 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
 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
 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
 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
 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
 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  */
 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  */
 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  */
 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
 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
 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 };