Botan 3.8.1
Crypto and TLS for C&
polyn_gf2m.h
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1/*
2 * (C) Copyright Projet SECRET, INRIA, Rocquencourt
3 * (C) Bhaskar Biswas and Nicolas Sendrier
4 *
5 * (C) 2014 cryptosource GmbH
6 * (C) 2014 Falko Strenzke fstrenzke@cryptosource.de
7 *
8 * Botan is released under the Simplified BSD License (see license.txt)
9 *
10 */
11
12#ifndef BOTAN_POLYN_GF2M_H_
13#define BOTAN_POLYN_GF2M_H_
14
15#include <botan/secmem.h>
16#include <memory>
17#include <utility>
18
19namespace Botan {
20
21typedef uint16_t gf2m;
22
23class GF2m_Field;
24
26
28 public:
29 /**
30 * create a zero polynomial:
31 */
32 explicit polyn_gf2m(const std::shared_ptr<GF2m_Field>& sp_field);
33
34 polyn_gf2m() : m_deg(-1) {}
35
36 polyn_gf2m(const secure_vector<uint8_t>& encoded, const std::shared_ptr<GF2m_Field>& sp_field);
37
38 polyn_gf2m& operator=(const polyn_gf2m&) = default;
39
40 /**
41 * create zero polynomial with reservation of space for a degree d polynomial
42 */
43 polyn_gf2m(int d, const std::shared_ptr<GF2m_Field>& sp_field);
44
45 polyn_gf2m(const polyn_gf2m& other);
46
47 /**
48 * random irreducible polynomial of degree t
49 */
50 polyn_gf2m(size_t t, RandomNumberGenerator& rng, const std::shared_ptr<GF2m_Field>& sp_field);
51
52 /** decode a polynomial from memory: **/
53 polyn_gf2m(const uint8_t* mem, uint32_t mem_len, const std::shared_ptr<GF2m_Field>& sp_field);
54
55 /**
56 * create a polynomial from memory area (encoded)
57 */
58 polyn_gf2m(int degree, const uint8_t* mem, size_t mem_byte_len, const std::shared_ptr<GF2m_Field>& sp_field);
59
60 bool operator==(const polyn_gf2m& other) const;
61
62 bool operator!=(const polyn_gf2m& other) const { return !(*this == other); }
63
64 polyn_gf2m(polyn_gf2m&& other) noexcept { this->swap(other); }
65
66 polyn_gf2m& operator=(polyn_gf2m&& other) noexcept {
67 if(this != &other) {
68 this->swap(other);
69 }
70 return *this;
71 }
72
73 void swap(polyn_gf2m& other) noexcept;
74
76
77 std::shared_ptr<GF2m_Field> get_sp_field() const { return m_sp_field; }
78
79 gf2m& operator[](size_t i) { return m_coeff[i]; }
80
81 gf2m operator[](size_t i) const { return m_coeff[i]; }
82
83 gf2m get_lead_coef() const { return m_coeff[m_deg]; }
84
85 gf2m get_coef(size_t i) const { return m_coeff[i]; }
86
87 inline void set_coef(size_t i, gf2m v) { m_coeff[i] = v; }
88
89 inline void add_to_coef(size_t i, gf2m v) { m_coeff[i] ^= v; }
90
91 void encode(uint32_t min_numo_coeffs, uint8_t* mem, uint32_t mem_len) const;
92
93 int get_degree() const;
94
95 /**
96 * determine the degree in a timing secure manner. the timing of this function
97 * only depends on the number of allocated coefficients, not on the actual
98 * degree
99 */
100 int calc_degree_secure() const;
101
102 static size_t degppf(const polyn_gf2m& g);
103
104 static std::vector<polyn_gf2m> sqmod_init(const polyn_gf2m& g);
105
106 static std::vector<polyn_gf2m> sqrt_mod_init(const polyn_gf2m& g);
107
108 polyn_gf2m sqmod(const std::vector<polyn_gf2m>& sq, int d);
109 void set_to_zero();
110 gf2m eval(gf2m a);
111
112 static std::pair<polyn_gf2m, polyn_gf2m> eea_with_coefficients(const polyn_gf2m& p,
113 const polyn_gf2m& g,
114 int break_deg);
115
116 void patchup_deg_secure(uint32_t trgt_deg, gf2m patch_elem);
117
118 private:
119 void set_degree(int d) { m_deg = d; }
120
121 void poly_shiftmod(const polyn_gf2m& g);
122 void realloc(uint32_t new_size);
123 static polyn_gf2m gcd(const polyn_gf2m& p1, const polyn_gf2m& p2);
124
125 /**
126 * destructive:
127 */
128 static void remainder(polyn_gf2m& p, const polyn_gf2m& g);
129
130 static polyn_gf2m gcd_aux(polyn_gf2m& p1, polyn_gf2m& p2);
131
132 private:
133 int m_deg;
134 secure_vector<gf2m> m_coeff;
135 std::shared_ptr<GF2m_Field> m_sp_field;
136};
137
138gf2m random_gf2m(RandomNumberGenerator& rng);
139gf2m random_code_element(uint16_t code_length, RandomNumberGenerator& rng);
140
141std::vector<polyn_gf2m> syndrome_init(const polyn_gf2m& generator, const std::vector<gf2m>& support, int n);
142
143/**
144* Find the roots of a polynomial over GF(2^m) using the method by Federenko et al.
145*/
146secure_vector<gf2m> find_roots_gf2m_decomp(const polyn_gf2m& polyn, size_t code_length);
147
148} // namespace Botan
149
150#endif
polyn_gf2m(const polyn_gf2m &other)
secure_vector< uint8_t > encode() const
int get_degree() const
std::shared_ptr< GF2m_Field > get_sp_field() const
Definition polyn_gf2m.h:77
bool operator!=(const polyn_gf2m &other) const
Definition polyn_gf2m.h:62
static std::pair< polyn_gf2m, polyn_gf2m > eea_with_coefficients(const polyn_gf2m &p, const polyn_gf2m &g, int break_deg)
void set_coef(size_t i, gf2m v)
Definition polyn_gf2m.h:87
polyn_gf2m(const std::shared_ptr< GF2m_Field > &sp_field)
gf2m get_coef(size_t i) const
Definition polyn_gf2m.h:85
void swap(polyn_gf2m &other) noexcept
gf2m get_lead_coef() const
Definition polyn_gf2m.h:83
void patchup_deg_secure(uint32_t trgt_deg, gf2m patch_elem)
polyn_gf2m & operator=(const polyn_gf2m &)=default
static std::vector< polyn_gf2m > sqmod_init(const polyn_gf2m &g)
static std::vector< polyn_gf2m > sqrt_mod_init(const polyn_gf2m &g)
void encode(uint32_t min_numo_coeffs, uint8_t *mem, uint32_t mem_len) const
polyn_gf2m & operator=(polyn_gf2m &&other) noexcept
Definition polyn_gf2m.h:66
gf2m operator[](size_t i) const
Definition polyn_gf2m.h:81
void add_to_coef(size_t i, gf2m v)
Definition polyn_gf2m.h:89
int calc_degree_secure() const
bool operator==(const polyn_gf2m &other) const
polyn_gf2m(polyn_gf2m &&other) noexcept
Definition polyn_gf2m.h:64
gf2m & operator[](size_t i)
Definition polyn_gf2m.h:79
polyn_gf2m sqmod(const std::vector< polyn_gf2m > &sq, int d)
gf2m eval(gf2m a)
static size_t degppf(const polyn_gf2m &g)
gf2m random_code_element(uint16_t code_length, RandomNumberGenerator &rng)
std::vector< polyn_gf2m > syndrome_init(const polyn_gf2m &generator, const std::vector< gf2m > &support, int n)
gf2m random_gf2m(RandomNumberGenerator &rng)
BigInt gcd(const BigInt &a, const BigInt &b)
Definition numthry.cpp:193
std::vector< T, secure_allocator< T > > secure_vector
Definition secmem.h:65
secure_vector< gf2m > find_roots_gf2m_decomp(const polyn_gf2m &polyn, size_t code_length)
uint16_t gf2m