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      1 /*############################################################################
      2   # Copyright 2016-2017 Intel Corporation
      3   #
      4   # Licensed under the Apache License, Version 2.0 (the "License");
      5   # you may not use this file except in compliance with the License.
      6   # You may obtain a copy of the License at
      7   #
      8   #     http://www.apache.org/licenses/LICENSE-2.0
      9   #
     10   # Unless required by applicable law or agreed to in writing, software
     11   # distributed under the License is distributed on an "AS IS" BASIS,
     12   # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13   # See the License for the specific language governing permissions and
     14   # limitations under the License.
     15   ############################################################################*/
     16 
     17 /*!
     18  * \file
     19  * \brief Pseudo random number generator implementation.
     20  */
     21 #include <ippcp.h>
     22 #include <stdlib.h>
     23 #include <time.h>
     24 
     25 #include "src/prng.h"
     26 
     27 EpidStatus PrngCreate(void** prng) {
     28   // Security note:
     29   // Random number generator used in the samples not claimed to be a
     30   // cryptographically secure pseudo-random number generator.
     31   EpidStatus sts = kEpidErr;
     32   int prng_ctx_size = 0;
     33   IppsPRNGState* prng_ctx = NULL;
     34   int seed_ctx_size = 0;
     35   IppsBigNumState* seed_ctx = NULL;
     36   time_t seed_value;
     37 
     38   if (!prng) return kEpidBadArgErr;
     39 
     40   if (ippStsNoErr != ippsPRNGGetSize(&prng_ctx_size)) return kEpidErr;
     41   if (ippStsNoErr !=
     42       ippsBigNumGetSize((sizeof(seed_value) + 3) / 4, &seed_ctx_size))
     43     return kEpidErr;
     44 
     45   do {
     46     prng_ctx = (IppsPRNGState*)calloc(1, prng_ctx_size);
     47 
     48     if (!prng_ctx) {
     49       sts = kEpidNoMemErr;
     50       break;
     51     }
     52     if (ippStsNoErr != ippsPRNGInit(sizeof(seed_value) * 8, prng_ctx)) {
     53       sts = kEpidErr;
     54       break;
     55     }
     56 
     57     // seed PRNG
     58     seed_ctx = (IppsBigNumState*)calloc(1, seed_ctx_size);
     59     if (!seed_ctx) {
     60       sts = kEpidNoMemErr;
     61       break;
     62     }
     63     if (ippStsNoErr != ippsBigNumInit((sizeof(seed_value) + 3) / 4, seed_ctx)) {
     64       sts = kEpidErr;
     65       break;
     66     }
     67     time(&seed_value);
     68     if (ippStsNoErr !=
     69         ippsSetOctString_BN((void*)&seed_value, sizeof(seed_value), seed_ctx)) {
     70       sts = kEpidErr;
     71       break;
     72     }
     73     if (ippStsNoErr != ippsPRNGSetSeed(seed_ctx, prng_ctx)) {
     74       sts = kEpidErr;
     75       break;
     76     }
     77 
     78     *prng = prng_ctx;
     79     prng_ctx = NULL;
     80     sts = kEpidNoErr;
     81   } while (0);
     82 
     83   if (seed_ctx) free(seed_ctx);
     84   if (prng_ctx) free(prng_ctx);
     85   return sts;
     86 }
     87 
     88 void PrngDelete(void** prng) {
     89   if (prng && *prng) {
     90     free(*prng);
     91     *prng = NULL;
     92   }
     93 }
     94 
     95 // simple wrapper to hide IPP implementation.
     96 int __STDCALL PrngGen(unsigned int* rand_data, int num_bits, void* user_data) {
     97   return ippsPRNGen(rand_data, num_bits, (IppsPRNGState*)user_data);
     98 }
     99