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112 lines
2.6 KiB
C++
112 lines
2.6 KiB
C++
//
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// DigestEngine.h
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//
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// Library: Foundation
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// Package: Crypt
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// Module: DigestEngine
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//
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// Definition of class DigestEngine.
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//
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// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_DigestEngine_INCLUDED
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#define Foundation_DigestEngine_INCLUDED
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#include "Poco/Foundation.h"
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#include <vector>
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namespace Poco {
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class Foundation_API DigestEngine
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/// This class is an abstract base class
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/// for all classes implementing a message
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/// digest algorithm, like MD5Engine
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/// and SHA1Engine.
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/// Call update() repeatedly with data to
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/// compute the digest from. When done,
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/// call digest() to obtain the message
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/// digest.
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{
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public:
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using Digest = std::vector<unsigned char>;
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DigestEngine();
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virtual ~DigestEngine();
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void update(const void* data, std::size_t length);
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void update(char data);
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void update(const std::string& data);
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/// Updates the digest with the given data.
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virtual std::size_t digestLength() const = 0;
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/// Returns the length of the digest in bytes.
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virtual void reset() = 0;
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/// Resets the engine so that a new
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/// digest can be computed.
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virtual const Digest& digest() = 0;
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/// Finishes the computation of the digest and
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/// returns the message digest. Resets the engine
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/// and can thus only be called once for every digest.
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/// The returned reference is valid until the next
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/// time digest() is called, or the engine object is destroyed.
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static std::string digestToHex(const Digest& bytes);
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/// Converts a message digest into a string of hexadecimal numbers.
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static Digest digestFromHex(const std::string& digest);
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/// Converts a string created by digestToHex back to its Digest presentation
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static bool constantTimeEquals(const Digest& d1, const Digest& d2);
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/// Compares two Digest values using a constant-time comparison
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/// algorithm. This can be used to prevent timing attacks
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/// (as discussed in <https://codahale.com/a-lesson-in-timing-attacks/>).
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protected:
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virtual void updateImpl(const void* data, std::size_t length) = 0;
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/// Updates the digest with the given data. Must be implemented
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/// by subclasses.
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private:
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DigestEngine(const DigestEngine&);
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DigestEngine& operator = (const DigestEngine&);
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};
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//
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// inlines
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//
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inline void DigestEngine::update(const void* data, std::size_t length)
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{
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updateImpl(data, length);
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}
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inline void DigestEngine::update(char data)
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{
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updateImpl(&data, 1);
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}
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inline void DigestEngine::update(const std::string& data)
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{
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updateImpl(data.data(), data.size());
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}
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} // namespace Poco
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#endif // Foundation_DigestEngine_INCLUDED
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