ReactOS  0.4.15-dev-509-g96a357b
mbedtls_ecp_group Struct Reference

ECP group structure. More...

`#include <ecp.h>`

Collaboration diagram for mbedtls_ecp_group: [legend]

## Public Attributes

mbedtls_ecp_group_id id

mbedtls_mpi P

mbedtls_mpi A

mbedtls_mpi B

mbedtls_ecp_point G

mbedtls_mpi N

size_t pbits

size_t nbits

unsigned int h

int(* modp )(mbedtls_mpi *)

int(* t_pre )(mbedtls_ecp_point *, void *)

int(* t_post )(mbedtls_ecp_point *, void *)

voidt_data

mbedtls_ecp_pointT

size_t T_size

## Detailed Description

ECP group structure.

We consider two types of curves equations:

1. Short Weierstrass y^2 = x^3 + A x + B mod P (SEC1 + RFC 4492)
2. Montgomery, y^2 = x^3 + A x^2 + x mod P (Curve25519 + draft) In both cases, a generator G for a prime-order subgroup is fixed. In the short weierstrass, this subgroup is actually the whole curve, and its cardinal is denoted by N.

In the case of Short Weierstrass curves, our code requires that N is an odd prime. (Use odd in mbedtls_ecp_mul() and prime in mbedtls_ecdsa_sign() for blinding.)

In the case of Montgomery curves, we don't store A but (A + 2) / 4 which is the quantity actually used in the formulas. Also, nbits is not the size of N but the required size for private keys.

If modp is NULL, reduction modulo P is done using a generic algorithm. Otherwise, it must point to a function that takes an mbedtls_mpi in the range 0..2^(2*pbits)-1 and transforms it in-place in an integer of little more than pbits, so that the integer may be efficiently brought in the 0..P-1 range by a few additions or substractions. It must return 0 on success and non-zero on failure.

Definition at line 173 of file ecp.h.

## ◆ A

 mbedtls_mpi mbedtls_ecp_group::A
1. A in the equation, or 2. (A + 2) / 4

Definition at line 177 of file ecp.h.

## ◆ B

 mbedtls_mpi mbedtls_ecp_group::B
1. B in the equation, or 2. unused

Definition at line 178 of file ecp.h.

## ◆ G

 mbedtls_ecp_point mbedtls_ecp_group::G

generator of the (sub)group used

Definition at line 179 of file ecp.h.

## ◆ h

 unsigned int mbedtls_ecp_group::h

internal: 1 if the constants are static

Definition at line 183 of file ecp.h.

## ◆ id

 mbedtls_ecp_group_id mbedtls_ecp_group::id

internal group identifier

Definition at line 175 of file ecp.h.

## ◆ modp

 int(* mbedtls_ecp_group::modp) (mbedtls_mpi *)

function for fast reduction mod P

Definition at line 184 of file ecp.h.

## ◆ N

 mbedtls_mpi mbedtls_ecp_group::N
1. the order of G, or 2. unused

Definition at line 180 of file ecp.h.

## ◆ nbits

 size_t mbedtls_ecp_group::nbits

number of bits in 1. P, or 2. private keys

Definition at line 182 of file ecp.h.

## ◆ P

 mbedtls_mpi mbedtls_ecp_group::P

prime modulus of the base field

Definition at line 176 of file ecp.h.

## ◆ pbits

 size_t mbedtls_ecp_group::pbits

number of bits in P

Definition at line 181 of file ecp.h.

## ◆ T

 mbedtls_ecp_point* mbedtls_ecp_group::T

pre-computed points for ecp_mul_comb()

Definition at line 188 of file ecp.h.

## ◆ t_data

 void* mbedtls_ecp_group::t_data

unused

Definition at line 187 of file ecp.h.

## ◆ t_post

 int(* mbedtls_ecp_group::t_post) (mbedtls_ecp_point *, void *)

unused

Definition at line 186 of file ecp.h.

## ◆ t_pre

 int(* mbedtls_ecp_group::t_pre) (mbedtls_ecp_point *, void *)

unused

Definition at line 185 of file ecp.h.

## ◆ T_size

 size_t mbedtls_ecp_group::T_size

number for pre-computed points

Definition at line 189 of file ecp.h.

The documentation for this struct was generated from the following file:
• sdk/include/reactos/libs/mbedtls/ecp.h