Botan::Classic_McEliece_Minimal_Polynomial Class Reference

Representation of a minimal polynomial in GF(q)[y]. More...

#include <cmce_poly.h>

Inheritance diagram for Botan::Classic_McEliece_Minimal_Polynomial:

Public Member Functions
void	_const_time_poison () const
void	_const_time_unpoison () const
	Classic_McEliece_Minimal_Polynomial (std::vector< Classic_McEliece_GF > coef)
const std::vector< Classic_McEliece_GF > &	coef () const
	Get the entire coefficients vector of the polynomial.
Classic_McEliece_GF &	coef_at (size_t i)
	Get the coefficient of the i-th monomial as a reference (from low to high degree).
const Classic_McEliece_GF &	coef_at (size_t i) const
	Get the coefficient of the i-th monomial (from low to high degree).
size_t	degree () const
	Get the degree of the polynomial.
Classic_McEliece_GF	operator() (Classic_McEliece_GF a) const
	Evaluate the polynomial P(x) at a given point a, i.e., compute P(a).
secure_vector< uint8_t >	serialize () const
	Serialize the polynomial to bytes according to ISO Section 9.2.9.

Static Public Member Functions
static Classic_McEliece_Minimal_Polynomial	from_bytes (std::span< const uint8_t > bytes, CmceGfMod poly_f)
	Create a polynomial from bytes according to ISO Section 9.2.9.

Detailed Description

Representation of a minimal polynomial in GF(q)[y].

It represents the monic irreducible degree-t polynomial of the goppa code.

Definition at line 81 of file cmce_poly.h.

Constructor & Destructor Documentation

Classic_McEliece_Minimal_Polynomial()

Botan::Classic_McEliece_Minimal_Polynomial::Classic_McEliece_Minimal_Polynomial ( std::vector< Classic_McEliece_GF > coef )

inline

Definition at line 83 of file cmce_poly.h.

                                                                               :
            Classic_McEliece_Polynomial(std::move(coef)) {}

Referenced by from_bytes().

Member Function Documentation

_const_time_poison()

void Botan::Classic_McEliece_Polynomial::_const_time_poison ( ) const

inlineinherited

Definition at line 68 of file cmce_poly.h.

{ CT::poison(m_coef); }

_const_time_unpoison()

void Botan::Classic_McEliece_Polynomial::_const_time_unpoison ( ) const

inlineinherited

Definition at line 70 of file cmce_poly.h.

{ CT::unpoison(m_coef); }

coef()

const std::vector< Classic_McEliece_GF > & Botan::Classic_McEliece_Polynomial::coef ( ) const

inlineinherited

Get the entire coefficients vector of the polynomial.

Definition at line 59 of file cmce_poly.h.

{ return m_coef; }

Referenced by serialize().

coef_at() [1/2]

Classic_McEliece_GF & Botan::Classic_McEliece_Polynomial::coef_at ( size_t i )

inlineinherited

Get the coefficient of the i-th monomial as a reference (from low to high degree).

Definition at line 49 of file cmce_poly.h.

{ return m_coef.at(i); }

Referenced by Botan::Classic_McEliece_PrivateKeyInternal::check_key(), Botan::Classic_McEliece_Polynomial_Ring::multiply(), and Botan::Classic_McEliece_Polynomial::operator()().

coef_at() [2/2]

const Classic_McEliece_GF & Botan::Classic_McEliece_Polynomial::coef_at ( size_t i ) const

inlineinherited

Get the coefficient of the i-th monomial (from low to high degree).

Definition at line 54 of file cmce_poly.h.

{ return m_coef.at(i); }

degree()

size_t Botan::Classic_McEliece_Polynomial::degree ( ) const

inlineinherited

Get the degree of the polynomial.

Note that the degree is given by the size of the coefficient vector, even if the leading coefficient is zero.

Definition at line 66 of file cmce_poly.h.

{ return m_coef.size() + 1; }

Referenced by Botan::Classic_McEliece_PrivateKeyInternal::check_key().

from_bytes()

Classic_McEliece_Minimal_Polynomial Botan::Classic_McEliece_Minimal_Polynomial::from_bytes ( std::span< const uint8_t > bytes, CmceGfMod poly_f )

static

Create a polynomial from bytes according to ISO Section 9.2.9.

Definition at line 141 of file cmce_poly.cpp.

                                                                                                      {
   BOTAN_ASSERT_NOMSG(bytes.size() % 2 == 0);
   const auto coef_vec = load_le<std::vector<CmceGfElem>>(bytes);
   std::vector<Classic_McEliece_GF> coeff_vec_gf;
   std::transform(coef_vec.begin(), coef_vec.end(), std::back_inserter(coeff_vec_gf), [poly_f](auto& coeff) {
      return Classic_McEliece_GF(coeff, poly_f);
   });
 
   coeff_vec_gf.emplace_back(CmceGfElem(1), poly_f);  // x^t as polynomial is monic
 
   return Classic_McEliece_Minimal_Polynomial(coeff_vec_gf);
}

References BOTAN_ASSERT_NOMSG, Classic_McEliece_Minimal_Polynomial(), and Botan::load_le().

Referenced by Botan::Classic_McEliece_PrivateKeyInternal::from_bytes().

operator()()

Classic_McEliece_GF Botan::Classic_McEliece_Polynomial::operator() ( Classic_McEliece_GF a ) const

inherited

Evaluate the polynomial P(x) at a given point a, i.e., compute P(a).

Definition at line 18 of file cmce_poly.cpp.

                                                                                       {
   BOTAN_DEBUG_ASSERT(a.modulus() == coef_at(0).modulus());
 
   Classic_McEliece_GF r(CmceGfElem(0), a.modulus());
   for(auto it = m_coef.rbegin(); it != m_coef.rend(); ++it) {
      r *= a;
      r += *it;
   }
 
   return r;
}

References BOTAN_DEBUG_ASSERT, Botan::Classic_McEliece_Polynomial::coef_at(), and Botan::Classic_McEliece_GF::modulus().

serialize()

secure_vector< uint8_t > Botan::Classic_McEliece_Minimal_Polynomial::serialize

(

)

const

Serialize the polynomial to bytes according to ISO Section 9.2.9.

Definition at line 127 of file cmce_poly.cpp.

                                                                            {
   BOTAN_ASSERT_NOMSG(!coef().empty());
   auto& all_coeffs = coef();
   // Store all except coef for monomial x^t since polynomial is monic (ISO Spec Section 9.2.9)
   auto coeffs_to_store = std::span(all_coeffs).first(all_coeffs.size() - 1);
   secure_vector<uint8_t> bytes(sizeof(uint16_t) * coeffs_to_store.size());
   BufferStuffer bytes_stuf(bytes);
   for(auto& coef : coeffs_to_store) {
      store_le(bytes_stuf.next<sizeof(CmceGfElem)>(), coef.elem().get());
   }
   BOTAN_ASSERT_NOMSG(bytes_stuf.full());
   return bytes;
}

References BOTAN_ASSERT_NOMSG, Botan::Classic_McEliece_Polynomial::coef(), Botan::BufferStuffer::full(), Botan::BufferStuffer::next(), and Botan::store_le().

Referenced by Botan::Classic_McEliece_PrivateKeyInternal::serialize().

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The documentation for this class was generated from the following files:

• src/lib/pubkey/classic_mceliece/cmce_poly.h
• src/lib/pubkey/classic_mceliece/cmce_poly.cpp