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// scrypt.h - written and placed in public domain by Jeffrey Walton.
// Based on reference source code by Colin Percival.
/// \file scrypt.h
/// \brief Classes for Scrypt from RFC 7914
/// \sa <A HREF="https://www.tarsnap.com/scrypt/scrypt.pdf">Stronger Key Derivation via
/// Sequential Memory-Hard Functions</a>,
/// <A HREF="https://www.tarsnap.com/scrypt.html">The scrypt key derivation function</A>
/// and <A HREF="https://tools.ietf.org/html/rfc7914">RFC 7914, The scrypt Password-Based
/// Key Derivation Function</A>
/// \since Crypto++ 7.0
#ifndef CRYPTOPP_SCRYPT_H
#define CRYPTOPP_SCRYPT_H
#include "cryptlib.h"
#include "secblock.h"
NAMESPACE_BEGIN(CryptoPP)
/// \brief Scrypt key derivation function
/// \details The Crypto++ implementation uses OpenMP to accelerate the derivation when
/// available.
/// \details The Crypto++ implementation of Scrypt is limited by C++ datatypes. For
/// example, the library is limited to a derived key length of <tt>SIZE_MAX</tt>,
/// and not <tt>(2^32 - 1) * 32</tt>.
/// \sa <A HREF="https://www.tarsnap.com/scrypt/scrypt.pdf">Stronger Key Derivation via
/// Sequential Memory-Hard Functions</A>,
/// <A HREF="https://www.tarsnap.com/scrypt.html">The scrypt key derivation function</A>
/// and <A HREF="https://tools.ietf.org/html/rfc7914">RFC 7914, The scrypt Password-Based
/// Key Derivation Function</A>
/// \since Crypto++ 7.0
class Scrypt : public KeyDerivationFunction
{
public:
virtual ~Scrypt() {}
static std::string StaticAlgorithmName () {
return "scrypt";
}
// KeyDerivationFunction interface
std::string AlgorithmName() const {
return StaticAlgorithmName();
}
// KeyDerivationFunction interface
size_t MaxDerivedKeyLength() const {
return static_cast<size_t>(0)-1;
}
// KeyDerivationFunction interface
size_t GetValidDerivedLength(size_t keylength) const;
// KeyDerivationFunction interface
size_t DeriveKey(byte *derived, size_t derivedLen, const byte *secret, size_t secretLen,
const NameValuePairs& params) const;
/// \brief Derive a key from a seed
/// \param derived the derived output buffer
/// \param derivedLen the size of the derived buffer, in bytes
/// \param secret the seed input buffer
/// \param secretLen the size of the secret buffer, in bytes
/// \param salt the salt input buffer
/// \param saltLen the size of the salt buffer, in bytes
/// \param cost the CPU/memory cost factor
/// \param blockSize the block size
/// \param parallelization the parallelization factor
/// \return the number of iterations performed
/// \throw InvalidDerivedKeyLength if <tt>derivedLen</tt> is invalid for the scheme
/// \details DeriveKey() provides a standard interface to derive a key from
/// a seed and other parameters. Each class that derives from KeyDerivationFunction
/// provides an overload that accepts most parameters used by the derivation function.
/// \details The CPU/Memory <tt>cost</tt> parameter ("N" in the documents) must be
/// larger than 1, a power of 2, and less than <tt>2^(128 * r / 8)</tt>.
/// \details The parameter <tt>blockSize</tt> ("r" in the documents) specifies the block
/// size.
/// \details The <tt>parallelization</tt> parameter ("p" in the documents) is a positive
/// integer less than or equal to <tt>((2^32-1) * 32) / (128 * r)</tt>. Due to Microsoft
/// and its OpenMP 2.0 implementation <tt>parallelization</tt> is limited to
/// <tt>std::numeric_limits<int>::max()</tt>.
/// \details Scrypt always returns 1 because it only performs 1 iteration. Other
/// derivation functions, like PBKDF's, will return more interesting values.
/// \details The Crypto++ implementation of Scrypt is limited by C++ datatypes. For
/// example, the library is limited to a derived key length of <tt>SIZE_MAX</tt>,
/// and not <tt>(2^32 - 1) * 32</tt>.
size_t DeriveKey(byte *derived, size_t derivedLen, const byte *secret, size_t secretLen,
const byte *salt, size_t saltLen, word64 cost=2, word64 blockSize=8, word64 parallelization=1) const;
protected:
enum {defaultCost=2, defaultBlockSize=8, defaultParallelization=1};
// KeyDerivationFunction interface
const Algorithm & GetAlgorithm() const {
return *this;
}
inline void ValidateParameters(size_t derivedlen, word64 cost, word64 blockSize, word64 parallelization) const;
};
NAMESPACE_END
#endif // CRYPTOPP_SCRYPT_H
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