Coverage Report

Created: 2022-06-23 06:44

/src/botan/build/include/botan/internal/polyn_gf2m.h
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/*
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 * (C) Copyright Projet SECRET, INRIA, Rocquencourt
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 * (C) Bhaskar Biswas and  Nicolas Sendrier
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 *
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 * (C) 2014 cryptosource GmbH
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 * (C) 2014 Falko Strenzke fstrenzke@cryptosource.de
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 *
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 * Botan is released under the Simplified BSD License (see license.txt)
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 *
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 */
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#ifndef BOTAN_POLYN_GF2M_H_
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#define BOTAN_POLYN_GF2M_H_
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#include <botan/secmem.h>
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#include <utility>
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#include <string>
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namespace Botan {
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typedef uint16_t gf2m;
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class GF2m_Field;
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class RandomNumberGenerator;
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class polyn_gf2m
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   {
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   public:
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      /**
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      * create a zero polynomial:
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      */
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      explicit polyn_gf2m(const std::shared_ptr<GF2m_Field>& sp_field);
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      polyn_gf2m() : m_deg(-1) {}
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      polyn_gf2m(const secure_vector<uint8_t>& encoded,
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                 const std::shared_ptr<GF2m_Field>& sp_field);
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      polyn_gf2m& operator=(const polyn_gf2m&) = default;
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      /**
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      * create zero polynomial with reservation of space for a degree d polynomial
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      */
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      polyn_gf2m(int d, const std::shared_ptr<GF2m_Field>& sp_field);
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      polyn_gf2m(polyn_gf2m const& other);
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      /**
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      * random irreducible polynomial of degree t
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      */
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      polyn_gf2m(size_t t, RandomNumberGenerator& rng,
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                 const std::shared_ptr<GF2m_Field>& sp_field);
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      /** decode a polynomial from memory: **/
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      polyn_gf2m(const uint8_t* mem, uint32_t mem_len, const std::shared_ptr<GF2m_Field>& sp_field);
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      /**
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      *  create a polynomial from memory area (encoded)
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      */
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      polyn_gf2m(int degree, const uint8_t* mem, size_t mem_byte_len,
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                 const std::shared_ptr<GF2m_Field>& sp_field);
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      bool operator==(const polyn_gf2m & other) const ;
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      bool operator!=(const polyn_gf2m & other) const { return !(*this == other); }
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      polyn_gf2m(polyn_gf2m&& other)
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         {
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         this->swap(other);
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         }
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      polyn_gf2m & operator=(polyn_gf2m&& other)
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         {
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         if(this != &other)
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            {
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            this->swap(other);
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            }
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         return *this;
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         }
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      void swap(polyn_gf2m& other);
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      secure_vector<uint8_t> encode() const;
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      std::shared_ptr<GF2m_Field> get_sp_field() const
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         { return m_sp_field; }
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      gf2m& operator[](size_t i) { return coeff[i]; }
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      gf2m operator[](size_t i) const { return coeff[i]; }
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      gf2m get_lead_coef() const { return coeff[m_deg]; }
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      gf2m get_coef(size_t i) const { return coeff[i]; }
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      inline void set_coef(size_t i, gf2m v)
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         {
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         coeff[i] = v;
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         }
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      inline void add_to_coef(size_t i, gf2m v)
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         {
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         coeff[i] ^= v;
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         }
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      std::string to_string() const;
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      void encode(uint32_t min_numo_coeffs, uint8_t* mem, uint32_t mem_len) const;
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      int get_degree() const;
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      /**
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      * determine the degree in a timing secure manner. the timing of this function
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      * only depends on the number of allocated coefficients, not on the actual
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      * degree
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      */
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      int calc_degree_secure() const;
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      size_t degppf(const polyn_gf2m& g);
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      static std::vector<polyn_gf2m> sqmod_init(const polyn_gf2m & g);
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      static std::vector<polyn_gf2m> sqrt_mod_init(const polyn_gf2m & g);
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      polyn_gf2m sqmod(const std::vector<polyn_gf2m> & sq, int d);
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      void set_to_zero();
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      gf2m eval(gf2m a);
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      static std::pair<polyn_gf2m, polyn_gf2m> eea_with_coefficients(const polyn_gf2m & p,
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                                                                     const polyn_gf2m & g,
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                                                                     int break_deg);
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      void patchup_deg_secure( uint32_t trgt_deg, gf2m patch_elem);
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   private:
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      void set_degree(int d) { m_deg = d; }
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      void poly_shiftmod( const polyn_gf2m & g);
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      void realloc(uint32_t new_size);
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      static polyn_gf2m gcd(polyn_gf2m const& p1, polyn_gf2m const& p2);
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      /**
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      * destructive:
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      */
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      static void remainder(polyn_gf2m & p, const polyn_gf2m & g);
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      static polyn_gf2m gcd_aux(polyn_gf2m& p1, polyn_gf2m& p2);
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   public:
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      // public member variable:
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      int m_deg;
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      // public member variable:
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      secure_vector<gf2m> coeff;
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      // public member variable:
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      std::shared_ptr<GF2m_Field> m_sp_field;
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   };
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gf2m random_gf2m(RandomNumberGenerator& rng);
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gf2m random_code_element(uint16_t code_length, RandomNumberGenerator& rng);
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std::vector<polyn_gf2m> syndrome_init(polyn_gf2m const& generator, std::vector<gf2m> const& support, int n);
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/**
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* Find the roots of a polynomial over GF(2^m) using the method by Federenko et al.
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*/
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secure_vector<gf2m> find_roots_gf2m_decomp(const polyn_gf2m & polyn, size_t code_length);
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}
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#endif