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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
* Copyright (c) 2013-2015 Regents of the University of California.
*
* This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
*
* ndn-cxx library is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
*
* You should have received copies of the GNU General Public License and GNU Lesser
* General Public License along with ndn-cxx, e.g., in COPYING.md file. If not, see
* <http://www.gnu.org/licenses/>.
*
* See AUTHORS.md for complete list of ndn-cxx authors and contributors.
*/
#ifndef NDN_UTIL_DIGEST_HPP
#define NDN_UTIL_DIGEST_HPP
#include "../encoding/buffer.hpp"
#include "../encoding/block.hpp"
#include "../security/cryptopp.hpp"
#include "concepts.hpp"
namespace ndn {
namespace util {
/**
* @brief provides a digest calculation
*
* Take SHA256 as an example:
*
* Digest<CryptoPP::SHA256> digest;
* digest.update(buf1, size1);
* digest.update(buf2, size2);
* ...
* ConstBufferPtr result = digest.computeDigest();
*
* @sa http://redmine.named-data.net/issues/1934
*/
template<typename Hash>
class Digest
{
public:
BOOST_CONCEPT_ASSERT((Hashable<Hash>));
typedef Hash HashFunction;
class Error : public std::runtime_error
{
public:
explicit
Error(const std::string& what)
: std::runtime_error(what)
{
}
};
Digest();
/**
* @brief Create digest of the input stream @p
* @param is input stream
*/
explicit
Digest(std::istream& is);
/**
* @brief Discard the current state and start a new digest.
*/
void
reset();
/**
* @brief Check if digest is empty.
*
* An empty digest means nothing has been taken into calculation.
*/
bool
empty() const
{
return !m_isInProcess;
}
/**
* @brief Obtain the digest
*
* Note this digest is finalized once this method is invoked.
*/
ConstBufferPtr
computeDigest();
/**
* @brief Check if supplied digest equal to this digest
*
* Note that this method will invoke computeDigest().
* Once this method is invoked, both this digest and the supplied digest are finalized.
*
* @warning This method cannot be used in security related context
* because it is vulnerable to timing attack
*/
bool
operator==(Digest<Hash>& digest);
/**
* @brief Check if supplied digest is not equal to this digest
*
* Note that this method will invoke computeDigest().
* Once this method is invoked, both this digest and the supplied digest are finalized.
*
* @warning This method cannot be used in security related context
* because it is vulnerable to timing attack
*/
bool
operator!=(Digest<Hash>& digest)
{
return !(*this == digest);
}
/**
* @brief Add existing digest to digest calculation
* @param src digest to combine with
*
* The result of this combination is hash (hash (...))
* Note that this method will invoke computeDigest().
* Once this method is invoked, the supplied digest is fixed.
*/
Digest<Hash>&
operator<<(Digest<Hash>& src);
/**
* @brief Add string to digest calculation
* @param str string to put into digest
*/
Digest<Hash>&
operator<<(const std::string& str);
/**
* @brief Add block to digest calculation
* @param block to put into digest
*/
Digest<Hash>&
operator<<(const Block& block);
/**
* @brief Add uint64_t value to digest calculation
* @param value uint64_t value to put into digest
*/
Digest<Hash>&
operator<<(uint64_t value);
/**
* @brief Add a buffer to digest calculation
*
* Update the state of the digest if it is not finalized
* and mark the digest as InProcess.
*
* @param buffer the input buffer
* @param size the size of the input buffer.
* @throws Error if the digest has been finalized.
*/
void
update(const uint8_t* buffer, size_t size);
/**
* @brief Compute one-time digest
* @param buffer the input buffer
* @param size the size of the input buffer.
* @return digest computed according to the HashAlgorithm
*/
static ConstBufferPtr
computeDigest(const uint8_t* buffer, size_t size);
/**
* @brief Convert digest to std::string
*
* Note that this method will invoke computeDigest().
* Once this method is invoked, the digest is finalized.
*/
std::string
toString();
private:
/**
* @brief Finalize digest.
*
* All subsequent calls to "operator<<" will throw an exception
*/
void
finalize();
private:
Hash m_hash;
BufferPtr m_buffer;
bool m_isInProcess;
bool m_isFinalized;
};
template<typename Hash>
std::ostream&
operator<<(std::ostream& os, Digest<Hash>& digest);
/**
* @brief A digest using SHA256 as the hash function.
*/
typedef Digest<CryptoPP::SHA256> Sha256;
} // namespace util
} // namespace ndn
#endif // NDN_UTIL_DIGEST_HPP