shake.h

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/*
* SHAKE hash functions
* (C) 2010,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#ifndef BOTAN_SHAKE_HASH_H_
#define BOTAN_SHAKE_HASH_H_
 
#include <botan/hash.h>
#include <botan/internal/keccak_perm.h>
 
#include <algorithm>
#include <string>
 
namespace Botan {
 
/**
* SHAKE-128
*/
class SHAKE_128 final : public HashFunction {
   public:
      /**
      * @param output_bits the desired output size in bits
      * must be a multiple of 8
      */
      explicit SHAKE_128(size_t output_bits);
 
      size_t hash_block_size() const override { return m_keccak.byte_rate(); }
 
      size_t output_length() const override { return m_output_bits / 8; }
 
      size_t security_level() const override { return std::min<size_t>(m_output_bits / 2, 128); }
 
      std::unique_ptr<HashFunction> new_object() const override;
      std::unique_ptr<HashFunction> copy_state() const override;
      std::string name() const override;
 
      void clear() override { m_keccak.clear(); }
 
      std::string provider() const override { return m_keccak.provider(); }
 
   private:
      void add_data(std::span<const uint8_t> input) override;
      void final_result(std::span<uint8_t> out) override;
 
      Keccak_Permutation m_keccak;
      size_t m_output_bits;
};
 
/**
* SHAKE-256
*/
class SHAKE_256 final : public HashFunction {
   public:
      /**
      * @param output_bits the desired output size in bits
      * must be a multiple of 8
      */
      explicit SHAKE_256(size_t output_bits);
 
      size_t hash_block_size() const override { return m_keccak.byte_rate(); }
 
      size_t output_length() const override { return m_output_bits / 8; }
 
      size_t security_level() const override { return std::min<size_t>(m_output_bits / 2, 256); }
 
      std::unique_ptr<HashFunction> new_object() const override;
      std::unique_ptr<HashFunction> copy_state() const override;
      std::string name() const override;
 
      void clear() override { m_keccak.clear(); }
 
      std::string provider() const override { return m_keccak.provider(); }
 
   private:
      void add_data(std::span<const uint8_t> input) override;
      void final_result(std::span<uint8_t> out) override;
 
      Keccak_Permutation m_keccak;
      size_t m_output_bits;
};
 
}  // namespace Botan
 
#endif