1 /* 2 * Copyright 2015 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 "hmac.h" 18 19 #include <assert.h> 20 21 #include <openssl/evp.h> 22 #include <openssl/hmac.h> 23 #include <openssl/mem.h> 24 #include <openssl/sha.h> 25 26 #include <keymaster/android_keymaster_utils.h> 27 28 namespace keymaster { 29 30 size_t HmacSha256::DigestLength() const { 31 return SHA256_DIGEST_LENGTH; 32 } 33 34 bool HmacSha256::Init(const Buffer& key) { 35 return Init(key.peek_read(), key.available_read()); 36 } 37 38 bool HmacSha256::Init(const uint8_t* key, size_t key_len) { 39 if (!key) 40 return false; 41 42 key_len_ = key_len; 43 key_.reset(dup_buffer(key, key_len)); 44 if (!key_.get()) { 45 return false; 46 } 47 return true; 48 } 49 50 bool HmacSha256::Sign(const Buffer& data, uint8_t* out_digest, size_t digest_len) const { 51 return Sign(data.peek_read(), data.available_read(), out_digest, digest_len); 52 } 53 54 bool HmacSha256::Sign(const uint8_t* data, size_t data_len, uint8_t* out_digest, 55 size_t digest_len) const { 56 assert(digest_len); 57 58 uint8_t tmp[SHA256_DIGEST_LENGTH]; 59 uint8_t* digest = tmp; 60 if (digest_len >= SHA256_DIGEST_LENGTH) 61 digest = out_digest; 62 63 if (nullptr == ::HMAC(EVP_sha256(), key_.get(), key_len_, data, data_len, digest, nullptr)) { 64 return false; 65 } 66 if (digest_len < SHA256_DIGEST_LENGTH) 67 memcpy(out_digest, tmp, digest_len); 68 69 return true; 70 } 71 72 bool HmacSha256::Verify(const Buffer& data, const Buffer& digest) const { 73 return Verify(data.peek_read(), data.available_read(), digest.peek_read(), 74 digest.available_read()); 75 } 76 77 bool HmacSha256::Verify(const uint8_t* data, size_t data_len, const uint8_t* digest, 78 size_t digest_len) const { 79 if (digest_len != SHA256_DIGEST_LENGTH) 80 return false; 81 82 uint8_t computed_digest[SHA256_DIGEST_LENGTH]; 83 if (!Sign(data, data_len, computed_digest, sizeof(computed_digest))) 84 return false; 85 86 return 0 == CRYPTO_memcmp(digest, computed_digest, SHA256_DIGEST_LENGTH); 87 } 88 89 } // namespace keymaster 90
