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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 <keymaster/android_keymaster_utils.h>
     18 
     19 #include <new>
     20 
     21 namespace keymaster {
     22 
     23 // Keymaster never manages enormous buffers, so anything particularly large is bad data or the
     24 // result of a bug.  We arbitrarily set a 16 MiB limit.
     25 const size_t kMaxDupBufferSize = 16 * 1024 * 1024;
     26 
     27 uint8_t* dup_buffer(const void* buf, size_t size) {
     28     if (size >= kMaxDupBufferSize)
     29         return nullptr;
     30     uint8_t* retval = new (std::nothrow) uint8_t[size];
     31     if (retval)
     32         memcpy(retval, buf, size);
     33     return retval;
     34 }
     35 
     36 int memcmp_s(const void* p1, const void* p2, size_t length) {
     37     const uint8_t* s1 = static_cast<const uint8_t*>(p1);
     38     const uint8_t* s2 = static_cast<const uint8_t*>(p2);
     39     uint8_t result = 0;
     40     while (length-- > 0)
     41         result |= *s1++ ^ *s2++;
     42     return result == 0 ? 0 : 1;
     43 }
     44 
     45 keymaster_error_t EcKeySizeToCurve(uint32_t key_size_bits, keymaster_ec_curve_t* curve) {
     46     switch (key_size_bits) {
     47     default:
     48         return KM_ERROR_UNSUPPORTED_KEY_SIZE;
     49 
     50     case 224:
     51         *curve = KM_EC_CURVE_P_224;
     52         break;
     53 
     54     case 256:
     55         *curve = KM_EC_CURVE_P_256;
     56         break;
     57 
     58     case 384:
     59         *curve = KM_EC_CURVE_P_384;
     60         break;
     61 
     62     case 521:
     63         *curve = KM_EC_CURVE_P_521;
     64         break;
     65     }
     66 
     67     return KM_ERROR_OK;
     68 }
     69 
     70 keymaster_error_t EcCurveToKeySize(keymaster_ec_curve_t curve, uint32_t* key_size_bits) {
     71     switch (curve) {
     72     default:
     73         return KM_ERROR_UNSUPPORTED_EC_CURVE;
     74 
     75     case KM_EC_CURVE_P_224:
     76         *key_size_bits = 224;
     77         break;
     78 
     79     case KM_EC_CURVE_P_256:
     80         *key_size_bits = 256;
     81         break;
     82 
     83     case KM_EC_CURVE_P_384:
     84         *key_size_bits = 384;
     85         break;
     86 
     87     case KM_EC_CURVE_P_521:
     88         *key_size_bits = 521;
     89         break;
     90     }
     91 
     92     return KM_ERROR_OK;
     93 }
     94 
     95 }  // namespace keymaster
     96