Botan
1.11.15
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00001 /** 00002 * (C) Copyright Projet SECRET, INRIA, Rocquencourt 00003 * (C) Bhaskar Biswas and Nicolas Sendrier 00004 * 00005 * (C) 2014 cryptosource GmbH 00006 * (C) 2014 Falko Strenzke fstrenzke@cryptosource.de 00007 * 00008 * Botan is released under the Simplified BSD License (see license.txt) 00009 * 00010 */ 00011 00012 #ifndef BOTAN_POLYN_GF2M_H__ 00013 #define BOTAN_POLYN_GF2M_H__ 00014 00015 #include <botan/gf2m_small_m.h> 00016 #include <botan/rng.h> 00017 #include <memory> 00018 #include <utility> 00019 00020 namespace Botan { 00021 00022 using namespace gf2m_small_m; 00023 00024 struct polyn_gf2m 00025 { 00026 public: 00027 /** 00028 * create a zero polynomial: 00029 */ 00030 polyn_gf2m( std::shared_ptr<gf2m_small_m::Gf2m_Field> sp_field ); 00031 00032 polyn_gf2m() 00033 :m_deg(-1) 00034 {}; 00035 00036 polyn_gf2m(const secure_vector<byte>& encoded, std::shared_ptr<gf2m_small_m::Gf2m_Field> sp_field ); 00037 00038 polyn_gf2m& operator=(const polyn_gf2m&) = default; 00039 00040 bool operator==(const polyn_gf2m & other) const ; 00041 00042 bool operator!=(const polyn_gf2m & other) const { return !(*this == other); }; 00043 00044 polyn_gf2m(polyn_gf2m&& other) 00045 { 00046 this->swap(other); 00047 }; 00048 00049 polyn_gf2m & operator=(polyn_gf2m&& other) 00050 { 00051 if(this != &other) 00052 { 00053 this->swap(other); 00054 } 00055 return *this; 00056 } 00057 00058 void swap(polyn_gf2m& other); 00059 00060 secure_vector<byte> encode() const; 00061 /** 00062 * create zero polynomial with reservation of space for a degree d polynomial 00063 */ 00064 polyn_gf2m(int d, std::shared_ptr<gf2m_small_m::Gf2m_Field> sp_field); 00065 00066 polyn_gf2m(polyn_gf2m const& other); 00067 /** 00068 * create zero polynomial with allocated size determined by specified degree d: 00069 */ 00070 00071 /** 00072 * random irreducible polynomial of degree t 00073 */ 00074 polyn_gf2m(int t, RandomNumberGenerator& rng, std::shared_ptr<gf2m_small_m::Gf2m_Field> sp_field); 00075 00076 std::shared_ptr<gf2m_small_m::Gf2m_Field> get_sp_field() const 00077 { return msp_field; }; 00078 00079 gf2m& operator[](size_t i) { return coeff[i]; }; 00080 00081 gf2m operator[](size_t i) const { return coeff[i]; } 00082 00083 gf2m get_lead_coef() const { return coeff[m_deg]; } 00084 00085 gf2m get_coef(u32bit i) const { return coeff[i]; } 00086 00087 inline void set_coef(u32bit i, gf2m v) 00088 { 00089 coeff[i] = v; 00090 }; 00091 00092 inline void add_to_coef(u32bit i, gf2m v) 00093 { 00094 coeff[i] = coeff[i] ^ v; 00095 } 00096 00097 std::string to_string() const; 00098 00099 /** decode a polynomial from memory: **/ 00100 polyn_gf2m(const byte* mem, u32bit mem_len, std::shared_ptr<gf2m_small_m::Gf2m_Field> sp_field); 00101 // remove one! ^v! 00102 /** 00103 * create a polynomial from memory area (encoded) 00104 */ 00105 polyn_gf2m(int degree, const unsigned char* mem, u32bit mem_byte_len, std::shared_ptr<gf2m_small_m::Gf2m_Field> sp_field); 00106 00107 void encode(u32bit min_numo_coeffs, byte* mem, u32bit mem_len) const; 00108 00109 int get_degree() const; 00110 00111 /** 00112 * determine the degree in a timing secure manner. the timing of this function 00113 * only depends on the number of allocated coefficients, not on the actual 00114 * degree 00115 */ 00116 int calc_degree_secure() const; 00117 00118 void degppf(const polyn_gf2m & g, int* p_result); 00119 00120 static std::vector<polyn_gf2m> sqmod_init(const polyn_gf2m & g); 00121 00122 static std::vector<polyn_gf2m> sqrt_mod_init(const polyn_gf2m & g); 00123 00124 00125 polyn_gf2m sqmod(const std::vector<polyn_gf2m> & sq, int d); 00126 void set_to_zero(); 00127 gf2m eval(gf2m a); 00128 00129 static std::pair<polyn_gf2m, polyn_gf2m> eea_with_coefficients(const polyn_gf2m & p, 00130 const polyn_gf2m & g, 00131 int break_deg); 00132 00133 void patchup_deg_secure( u32bit trgt_deg, volatile gf2m patch_elem); 00134 00135 private: 00136 00137 void set_degree(int d) { m_deg = d; } 00138 00139 void poly_shiftmod( const polyn_gf2m & g); 00140 void realloc(u32bit new_size); 00141 static polyn_gf2m gcd(polyn_gf2m const& p1, polyn_gf2m const& p2); 00142 00143 /** 00144 * destructive: 00145 */ 00146 static void remainder(polyn_gf2m & p, const polyn_gf2m & g); 00147 00148 static polyn_gf2m gcd_aux(polyn_gf2m& p1, polyn_gf2m& p2); 00149 public: 00150 int m_deg; 00151 secure_vector<gf2m> coeff; 00152 std::shared_ptr<gf2m_small_m::Gf2m_Field> msp_field; 00153 }; 00154 00155 gf2m random_code_element(unsigned code_length, RandomNumberGenerator& rng); 00156 00157 std::vector<polyn_gf2m> syndrome_init(polyn_gf2m const& generator, std::vector<gf2m> const& support, int n); 00158 00159 } 00160 00161 #endif