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      1 /*
      2  * Copyright 2014 The Android Open Source Project
      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 #include <openssl/bn.h>
     18 
     19 #include "dsa_operation.h"
     20 #include "openssl_utils.h"
     21 
     22 namespace keymaster {
     23 
     24 DsaOperation::~DsaOperation() {
     25     if (dsa_key_ != NULL)
     26         DSA_free(dsa_key_);
     27 }
     28 
     29 keymaster_error_t DsaOperation::Update(const Buffer& input, Buffer* /* output */) {
     30     switch (purpose()) {
     31     default:
     32         return KM_ERROR_UNIMPLEMENTED;
     33     case KM_PURPOSE_SIGN:
     34     case KM_PURPOSE_VERIFY:
     35         return StoreData(input);
     36     }
     37 }
     38 
     39 keymaster_error_t DsaOperation::StoreData(const Buffer& input) {
     40     if (!data_.reserve(data_.available_read() + input.available_read()) ||
     41         !data_.write(input.peek_read(), input.available_read()))
     42         return KM_ERROR_INVALID_INPUT_LENGTH;
     43     return KM_ERROR_OK;
     44 }
     45 
     46 keymaster_error_t DsaSignOperation::Finish(const Buffer& /* signature */, Buffer* output) {
     47     output->Reinitialize(DSA_size(dsa_key_));
     48     unsigned int siglen;
     49     if (!DSA_sign(0 /* type -- ignored */, data_.peek_read(), data_.available_read(),
     50                   output->peek_write(), &siglen, dsa_key_))
     51         return KM_ERROR_UNKNOWN_ERROR;
     52     output->advance_write(siglen);
     53     return KM_ERROR_OK;
     54 }
     55 
     56 keymaster_error_t DsaVerifyOperation::Finish(const Buffer& signature, Buffer* /* output */) {
     57     if ((int)data_.available_read() != DSA_size(dsa_key_))
     58         return KM_ERROR_INVALID_INPUT_LENGTH;
     59 
     60     int result = DSA_verify(0 /* type -- ignored */, data_.peek_read(), data_.available_read(),
     61                             signature.peek_read(), signature.available_read(), dsa_key_);
     62     if (result < 0)
     63         return KM_ERROR_UNKNOWN_ERROR;
     64     else if (result == 0)
     65         return KM_ERROR_VERIFICATION_FAILED;
     66     else
     67         return KM_ERROR_OK;
     68 }
     69 
     70 }  // namespace keymaster
     71