Coverage Report

Created: 2020-05-23 13:54

/src/botan/src/lib/kdf/prf_x942/prf_x942.cpp
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Source (jump to first uncovered line)
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/*
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* X9.42 PRF
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* (C) 1999-2007 Jack Lloyd
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*
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* Botan is released under the Simplified BSD License (see license.txt)
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*/
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#include <botan/prf_x942.h>
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#include <botan/der_enc.h>
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#include <botan/hash.h>
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#include <botan/loadstor.h>
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#include <algorithm>
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namespace Botan {
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namespace {
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/*
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* Encode an integer as an OCTET STRING
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*/
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std::vector<uint8_t> encode_x942_int(uint32_t n)
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   {
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   uint8_t n_buf[4] = { 0 };
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   store_be(n, n_buf);
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   std::vector<uint8_t> output;
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   DER_Encoder(output).encode(n_buf, 4, OCTET_STRING);
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   return output;
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   }
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}
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size_t X942_PRF::kdf(uint8_t key[], size_t key_len,
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                     const uint8_t secret[], size_t secret_len,
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                     const uint8_t salt[], size_t salt_len,
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                     const uint8_t label[], size_t label_len) const
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   {
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   std::unique_ptr<HashFunction> hash(HashFunction::create("SHA-160"));
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   secure_vector<uint8_t> h;
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   secure_vector<uint8_t> in;
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   size_t offset = 0;
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   uint32_t counter = 1;
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   in.reserve(salt_len + label_len);
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   in += std::make_pair(label,label_len);
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   in += std::make_pair(salt,salt_len);
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   while(offset != key_len && counter)
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      {
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      hash->update(secret, secret_len);
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      hash->update(
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         DER_Encoder().start_cons(SEQUENCE)
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            .start_cons(SEQUENCE)
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               .encode(m_key_wrap_oid)
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               .raw_bytes(encode_x942_int(counter))
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            .end_cons()
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            .encode_if(salt_len != 0,
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               DER_Encoder()
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                  .start_explicit(0)
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                     .encode(in, OCTET_STRING)
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                  .end_explicit()
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               )
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            .start_explicit(2)
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               .raw_bytes(encode_x942_int(static_cast<uint32_t>(8 * key_len)))
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            .end_explicit()
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         .end_cons().get_contents()
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         );
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      hash->final(h);
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      const size_t copied = std::min(h.size(), key_len - offset);
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      copy_mem(&key[offset], h.data(), copied);
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      offset += copied;
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      ++counter;
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      }
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   return offset;
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   }
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std::string X942_PRF::name() const
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   {
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   return "X9.42-PRF(" + m_key_wrap_oid.to_formatted_string() + ")";
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   }
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}