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- /*############################################################################
- # Copyright 2016-2017 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.
- ############################################################################*/
- /*!
- * \file
- * \brief Verify implementation.
- */
- #include <string.h>
- #include "epid/common/src/endian_convert.h"
- #include "epid/verifier/api.h"
- #include "epid/verifier/src/context.h"
- /// Handle SDK Error with Break
- #define BREAK_ON_EPID_ERROR(ret) \
- if (kEpidNoErr != (ret)) { \
- break; \
- }
- static size_t EpidGetSignatureRlCount(EpidSignature const* sig) {
- if (!sig)
- return 0;
- else
- return ntohl(sig->n2);
- }
- static size_t EpidGetGroupRlCount(GroupRl const* rl) {
- if (!rl)
- return 0;
- else
- return ntohl(rl->n3);
- }
- static size_t EpidGetPrivRlCount(PrivRl const* rl) {
- if (!rl)
- return 0;
- else
- return ntohl(rl->n1);
- }
- static size_t EpidGetSigRlCount(SigRl const* rl) {
- if (!rl)
- return 0;
- else
- return ntohl(rl->n2);
- }
- static size_t EpidGetVerifierRlCount(VerifierRl const* rl) {
- if (!rl)
- return 0;
- else
- return ntohl(rl->n4);
- }
- // implements section 4.1.2 "Verify algorithm" from Intel(R) EPID 2.0 Spec
- EpidStatus EpidVerify(VerifierCtx const* ctx, EpidSignature const* sig,
- size_t sig_len, void const* msg, size_t msg_len) {
- // Step 1. Setup
- size_t const sig_header_len = (sizeof(EpidSignature) - sizeof(NrProof));
- EpidStatus sts = kEpidErr;
- size_t rl_count = 0;
- size_t i;
- if (!ctx || !sig) {
- return kEpidBadArgErr;
- }
- if (!msg && (0 != msg_len)) {
- // if message is non-empty it must have both length and content
- return kEpidBadArgErr;
- }
- if (!ctx->epid2_params || !ctx->pub_key) {
- return kEpidBadArgErr;
- }
- if (sig_len < sig_header_len) {
- return kEpidBadArgErr;
- }
- rl_count = EpidGetSignatureRlCount(sig);
- if (rl_count > (SIZE_MAX - sig_header_len) / sizeof(sig->sigma[0]) ||
- (rl_count * sizeof(sig->sigma[0])) + sig_header_len != sig_len) {
- return kEpidBadArgErr;
- }
- // Step 2. The verifier verifies the basic signature Sigma0 as follows:
- sts = EpidVerifyBasicSig(ctx, &sig->sigma0, msg, msg_len);
- if (sts != kEpidNoErr) {
- // p. If any of the above verifications fails, the verifier aborts and
- // outputs 1
- return kEpidSigInvalid;
- }
- // Step 3. If GroupRL is provided,
- if (ctx->group_rl) {
- // a. The verifier verifies that gid does not match any entry in GroupRL.
- size_t grouprl_count = EpidGetGroupRlCount(ctx->group_rl);
- for (i = 0; i < grouprl_count; ++i) {
- if (0 == memcmp(&ctx->pub_key->gid, &ctx->group_rl->gid[i],
- sizeof(ctx->pub_key->gid))) {
- // b. If gid matches an entry in GroupRL, aborts and returns 2.
- return kEpidSigRevokedInGroupRl;
- }
- }
- }
- // Step 4. If PrivRL is provided,
- if (ctx->priv_rl) {
- size_t privrl_count = EpidGetPrivRlCount(ctx->priv_rl);
- // a. The verifier verifies that gid in the public key and in PrivRL match.
- // If mismatch, abort and return "operation failed".
- if (0 != memcmp(&ctx->pub_key->gid, &ctx->priv_rl->gid,
- sizeof(ctx->pub_key->gid))) {
- return kEpidBadArgErr;
- }
- // b. For i = 0, ..., n1-1, the verifier computes t4 =G1.exp(B, f[i]) and
- // verifies that G1.isEqual(t4, K) = false. A faster private-key revocation
- // check algorithm is provided in Section 4.5.
- for (i = 0; i < privrl_count; ++i) {
- sts = EpidCheckPrivRlEntry(ctx, &sig->sigma0, &ctx->priv_rl->f[i]);
- if (sts != kEpidNoErr) {
- // c. If the above step fails, the verifier aborts and output 3.
- return kEpidSigRevokedInPrivRl;
- }
- }
- }
- // Step 5. If SigRL is provided,
- if (ctx->sig_rl) {
- size_t sigrl_count = EpidGetSigRlCount(ctx->sig_rl);
- // a. The verifier verifies that gid in the public key and in SigRL match.
- // If mismatch, abort and return "operation failed".
- if (0 != memcmp(&ctx->pub_key->gid, &ctx->sig_rl->gid,
- sizeof(ctx->pub_key->gid))) {
- return kEpidBadArgErr;
- }
- // b. The verifier verifies that RLver in Sigma and in SigRL match. If
- // mismatch, abort and output "operation failed".
- if (0 != memcmp(&ctx->sig_rl->version, &sig->rl_ver,
- sizeof(ctx->sig_rl->version))) {
- return kEpidErr;
- }
- // c. The verifier verifies that n2 in Sigma and in SigRL match. If
- // mismatch, abort and output "operation failed".
- if (sigrl_count != rl_count) {
- return kEpidBadArgErr;
- }
- // d. For i = 0, ..., n2-1, the verifier verifies nrVerify(B, K, B[i],
- // K[i], Sigma[i]) = true. The details of nrVerify() will be given in the
- // next subsection.
- for (i = 0; i < sigrl_count; ++i) {
- sts = EpidNrVerify(ctx, &sig->sigma0, msg, msg_len, &ctx->sig_rl->bk[i],
- &sig->sigma[i]);
- if (sts != kEpidNoErr) {
- // e. If the above step fails, the verifier aborts and output 4.
- return kEpidSigRevokedInSigRl;
- }
- }
- }
- // Step 6. If VerifierRL is provided,
- if (ctx->verifier_rl) {
- // a. The verifier verifies that gid in the public key and in VerifierRL
- // match. If mismatch, abort and return "operation failed".
- if (0 != memcmp(&ctx->pub_key->gid, &ctx->verifier_rl->gid,
- sizeof(ctx->pub_key->gid))) {
- return kEpidBadArgErr;
- }
- // b. The verifier verifies that B in the signature and in VerifierRL
- // match. If mismatch, go to step 7.
- if (0 ==
- memcmp(&ctx->verifier_rl->B, &sig->sigma0.B, sizeof(sig->sigma0.B))) {
- size_t verifierrl_count = EpidGetVerifierRlCount(ctx->verifier_rl);
- // c. For i = 0, ..., n4-1, the verifier verifies that K != K[i].
- for (i = 0; i < verifierrl_count; ++i) {
- if (0 == memcmp(&ctx->verifier_rl->K[i], &sig->sigma0.K,
- sizeof(sig->sigma0.K))) {
- // d. If the above step fails, the verifier aborts and output 5.
- return kEpidSigRevokedInVerifierRl;
- }
- }
- }
- }
- // Step 7. If all the above verifications succeed, the verifier outputs 0.
- return kEpidSigValid;
- }
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