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83 lines
2.9 KiB
83 lines
2.9 KiB
/* |
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* Copyright 2015 The Android Open Source Project |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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#include "iso18033kdf.h" |
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#include "openssl_utils.h" |
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#include <openssl/evp.h> |
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namespace keymaster { |
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inline size_t min(size_t a, size_t b) { |
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return (a < b) ? a : b; |
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} |
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bool Iso18033Kdf::GenerateKey(const uint8_t* info, size_t info_len, uint8_t* output, |
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size_t output_len) { |
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if (!is_initialized_ || output == nullptr) |
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return false; |
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/* Check whether output length is too long as specified in ISO/IEC 18033-2. */ |
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if ((0xFFFFFFFFULL + start_counter_) * digest_size_ < (uint64_t)output_len) |
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return false; |
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EVP_MD_CTX ctx; |
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EvpMdCtxCleaner ctxCleaner(&ctx); |
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EVP_MD_CTX_init(&ctx); |
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size_t num_blocks = (output_len + digest_size_ - 1) / digest_size_; |
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UniquePtr<uint8_t[]> counter(new uint8_t[4]); |
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UniquePtr<uint8_t[]> digest_result(new uint8_t[digest_size_]); |
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if (counter.get() == nullptr || digest_result.get() == nullptr) |
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return false; |
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for (size_t block = 0; block < num_blocks; block++) { |
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switch (digest_type_) { |
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case KM_DIGEST_SHA1: |
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if (!EVP_DigestInit_ex(&ctx, EVP_sha1(), nullptr /* default digest */)) |
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return false; |
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break; |
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case KM_DIGEST_SHA_2_256: |
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if (!EVP_DigestInit_ex(&ctx, EVP_sha256(), nullptr /* default digest */)) |
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return false; |
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break; |
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default: |
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return false; |
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} |
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if (!EVP_DigestUpdate(&ctx, secret_key_.get(), secret_key_len_) || |
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!Uint32ToBigEndianByteArray(block + start_counter_, counter.get()) || |
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!EVP_DigestUpdate(&ctx, counter.get(), 4)) |
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return false; |
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if (info != nullptr && info_len > 0) { |
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if (!EVP_DigestUpdate(&ctx, info, info_len)) |
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return false; |
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} |
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/* OpenSSL does not accept size_t parameter. */ |
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uint32_t uint32_digest_size_ = digest_size_; |
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if (!EVP_DigestFinal_ex(&ctx, digest_result.get(), &uint32_digest_size_) || |
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uint32_digest_size_ != digest_size_) |
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return false; |
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size_t block_start = digest_size_ * block; |
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size_t block_length = min(digest_size_, output_len - block_start); |
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memcpy(output + block_start, digest_result.get(), block_length); |
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} |
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return true; |
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} |
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} // namespace keymaster
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