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      1 /*############################################################################
      2   # Copyright 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 /// Host signing helper implementation
     17 /*! \file */
     18 
     19 #include "epid/member/src/sign_commitment.h"
     20 
     21 #include "epid/common/math/ecgroup.h"
     22 #include "epid/common/src/commitment.h"
     23 
     24 /// Handle SDK Error with Break
     25 #define BREAK_ON_EPID_ERROR(ret) \
     26   if (kEpidNoErr != (ret)) {     \
     27     break;                       \
     28   }
     29 
     30 EpidStatus HashSignCommitment(FiniteField* Fp, HashAlg hash_alg,
     31                               GroupPubKey const* pub_key,
     32                               SignCommitOutput const* commit_out,
     33                               void const* msg, size_t msg_len,
     34                               FpElemStr* c_str) {
     35   EpidStatus sts = kEpidErr;
     36   FfElement* c = NULL;
     37 
     38   if (!Fp || !commit_out || (0 != msg_len && !msg) || !c_str) {
     39     return kEpidBadArgErr;
     40   }
     41 
     42   do {
     43     CommitValues values = {0};
     44     sts = SetKeySpecificCommitValues(pub_key, &values);
     45     BREAK_ON_EPID_ERROR(sts);
     46 
     47     values.B = commit_out->B;
     48     values.K = commit_out->K;
     49     values.T = commit_out->T;
     50     values.R1 = commit_out->R1;
     51     values.R2 = commit_out->R2;
     52 
     53     sts = NewFfElement(Fp, &c);
     54     BREAK_ON_EPID_ERROR(sts);
     55 
     56     // 5.  The member computes t3 = Fp.hash(p || g1 || g2 || h1 || h2
     57     //     || w || B || K || T || R1 || R2).
     58     // 6.  The member computes c = Fp.hash(t3 || m).
     59     sts = CalculateCommitmentHash(&values, Fp, hash_alg, msg, msg_len, c);
     60     BREAK_ON_EPID_ERROR(sts);
     61 
     62     sts = WriteFfElement(Fp, c, c_str, sizeof(*c_str));
     63     BREAK_ON_EPID_ERROR(sts);
     64 
     65     sts = kEpidNoErr;
     66   } while (0);
     67 
     68   DeleteFfElement(&c);
     69 
     70   return sts;
     71 }
     72