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- /*############################################################################
- # Copyright 2017 Intel Corporation
- #
- # Licensed under the Apache License, Version 2.0 (the "License");
- # you may not use this file except in compliance with the License.
- # You may obtain a copy of the License at
- #
- # http://www.apache.org/licenses/LICENSE-2.0
- #
- # Unless required by applicable law or agreed to in writing, software
- # distributed under the License is distributed on an "AS IS" BASIS,
- # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- # See the License for the specific language governing permissions and
- # limitations under the License.
- ############################################################################*/
- /// Member private exponentiation implementation
- /*! \file */
- #include "epid/member/src/privateexp.h"
- #include "epid/common/math/ecgroup.h"
- #include "epid/common/src/epid2params.h"
- #include "epid/common/src/hashsize.h"
- #include "epid/common/src/memory.h"
- #include "epid/common/types.h"
- #include "epid/member/src/context.h"
- #include "epid/member/tpm2/commit.h"
- #include "epid/member/tpm2/sign.h"
- /// Handle Intel(R) EPID Error with Break
- #define BREAK_ON_EPID_ERROR(ret) \
- if (kEpidNoErr != (ret)) { \
- break; \
- }
- EpidStatus EpidPrivateExp(MemberCtx* ctx, EcPoint const* a, EcPoint* r) {
- EpidStatus sts = kEpidErr;
- BigNumStr tmp_ff_str = {0};
- uint16_t counter = 0;
- EcPoint* k_pt = NULL;
- EcPoint* l_pt = NULL;
- EcPoint* e_pt = NULL;
- EcPoint* t1 = NULL;
- EcPoint* h = NULL;
- FfElement* k = NULL;
- FfElement* s = NULL;
- size_t digest_len = 0;
- uint8_t* digest = NULL;
- if (!ctx || !ctx->epid2_params || !a || !r) {
- return kEpidBadArgErr;
- }
- digest_len = EpidGetHashSize(ctx->hash_alg);
- digest = SAFE_ALLOC(digest_len);
- if (!digest) {
- return kEpidMemAllocErr;
- }
- memset(digest, 0, digest_len);
- digest[digest_len - 1] = 1;
- do {
- FiniteField* Fp = ctx->epid2_params->Fp;
- EcGroup* G1 = ctx->epid2_params->G1;
- if (!ctx->is_provisioned && !ctx->is_initially_provisioned) {
- sts = EpidMemberInitialProvision(ctx);
- BREAK_ON_EPID_ERROR(sts);
- }
- // (K_PT, L_PT, E_PT, counter) = TPM2_Commit(P1=B')
- sts = NewEcPoint(G1, &k_pt);
- BREAK_ON_EPID_ERROR(sts);
- sts = NewEcPoint(G1, &l_pt);
- BREAK_ON_EPID_ERROR(sts);
- sts = NewEcPoint(G1, &e_pt);
- BREAK_ON_EPID_ERROR(sts);
- sts = NewEcPoint(G1, &t1);
- BREAK_ON_EPID_ERROR(sts);
- sts = NewEcPoint(G1, &h);
- BREAK_ON_EPID_ERROR(sts);
- sts =
- Tpm2Commit(ctx->tpm2_ctx, a, NULL, 0, NULL, k_pt, l_pt, e_pt, &counter);
- BREAK_ON_EPID_ERROR(sts);
- // (k, s) = TPM2_Sign(c=1, counter)
- sts = NewFfElement(Fp, &k);
- BREAK_ON_EPID_ERROR(sts);
- sts = NewFfElement(Fp, &s);
- BREAK_ON_EPID_ERROR(sts);
- sts = Tpm2Sign(ctx->tpm2_ctx, digest, digest_len, counter, k, s);
- BREAK_ON_EPID_ERROR(sts);
- // k = Fq.inv(k)
- sts = FfInv(Fp, k, k);
- BREAK_ON_EPID_ERROR(sts);
- // t1 = G1.sscmExp(B', s)
- sts = WriteFfElement(Fp, s, &tmp_ff_str, sizeof(tmp_ff_str));
- BREAK_ON_EPID_ERROR(sts);
- sts = EcSscmExp(G1, a, &tmp_ff_str, t1);
- BREAK_ON_EPID_ERROR(sts);
- // E_PT = G1.inv(E_PT)
- sts = EcInverse(G1, e_pt, e_pt);
- BREAK_ON_EPID_ERROR(sts);
- // h = G1.mul(t1, E_PT)
- sts = EcMul(G1, t1, e_pt, h);
- BREAK_ON_EPID_ERROR(sts);
- // h = G1.sscmExp(h, k)
- sts = WriteFfElement(Fp, k, &tmp_ff_str, sizeof(tmp_ff_str));
- BREAK_ON_EPID_ERROR(sts);
- sts = EcSscmExp(G1, h, &tmp_ff_str, r);
- BREAK_ON_EPID_ERROR(sts);
- } while (0);
- if (sts != kEpidNoErr) {
- (void)Tpm2ReleaseCounter(ctx->tpm2_ctx, counter);
- }
- DeleteFfElement(&s);
- DeleteFfElement(&k);
- DeleteEcPoint(&e_pt);
- DeleteEcPoint(&l_pt);
- DeleteEcPoint(&k_pt);
- DeleteEcPoint(&t1);
- DeleteEcPoint(&h);
- EpidZeroMemory(&tmp_ff_str, sizeof(tmp_ff_str));
- SAFE_FREE(digest);
- return sts;
- }
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