1  // Copyright (c) 2018-present The Bitcoin Core developers
 2  // Distributed under the MIT software license, see the accompanying
 3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 4  
 5  #include <crypto/hkdf_sha256_32.h>
 6  
 7  #include <crypto/hmac_sha256.h>
 8  
 9  #include <cassert>
10  
11  CHKDF_HMAC_SHA256_L32::CHKDF_HMAC_SHA256_L32(const unsigned char* ikm, size_t ikmlen, const std::string& salt)
12  {
13      CHMAC_SHA256((const unsigned char*)salt.data(), salt.size()).Write(ikm, ikmlen).Finalize(m_prk);
14  }
15  
16  void CHKDF_HMAC_SHA256_L32::Expand32(const std::string& info, unsigned char hash[OUTPUT_SIZE])
17  {
18      // expand a 32byte key (single round)
19      assert(info.size() <= 128);
20      static const unsigned char one[1] = {1};
21      CHMAC_SHA256(m_prk, 32).Write((const unsigned char*)info.data(), info.size()).Write(one, 1).Finalize(hash);
22  }