4746f25ac6
[skip ci] Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/7829)
233 lines
11 KiB
Text
233 lines
11 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
EC_POINT_set_Jprojective_coordinates_GFp,
|
|
EC_POINT_point2buf,
|
|
EC_POINT_new,
|
|
EC_POINT_free,
|
|
EC_POINT_clear_free,
|
|
EC_POINT_copy,
|
|
EC_POINT_dup,
|
|
EC_POINT_method_of,
|
|
EC_POINT_set_to_infinity,
|
|
EC_POINT_get_Jprojective_coordinates_GFp,
|
|
EC_POINT_set_affine_coordinates,
|
|
EC_POINT_get_affine_coordinates,
|
|
EC_POINT_set_compressed_coordinates,
|
|
EC_POINT_set_affine_coordinates_GFp,
|
|
EC_POINT_get_affine_coordinates_GFp,
|
|
EC_POINT_set_compressed_coordinates_GFp,
|
|
EC_POINT_set_affine_coordinates_GF2m,
|
|
EC_POINT_get_affine_coordinates_GF2m,
|
|
EC_POINT_set_compressed_coordinates_GF2m,
|
|
EC_POINT_point2oct,
|
|
EC_POINT_oct2point,
|
|
EC_POINT_point2bn,
|
|
EC_POINT_bn2point,
|
|
EC_POINT_point2hex,
|
|
EC_POINT_hex2point
|
|
- Functions for creating, destroying and manipulating EC_POINT objects
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/ec.h>
|
|
|
|
EC_POINT *EC_POINT_new(const EC_GROUP *group);
|
|
void EC_POINT_free(EC_POINT *point);
|
|
void EC_POINT_clear_free(EC_POINT *point);
|
|
int EC_POINT_copy(EC_POINT *dst, const EC_POINT *src);
|
|
EC_POINT *EC_POINT_dup(const EC_POINT *src, const EC_GROUP *group);
|
|
const EC_METHOD *EC_POINT_method_of(const EC_POINT *point);
|
|
int EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point);
|
|
int EC_POINT_set_Jprojective_coordinates_GFp(const EC_GROUP *group,
|
|
EC_POINT *p,
|
|
const BIGNUM *x, const BIGNUM *y,
|
|
const BIGNUM *z, BN_CTX *ctx);
|
|
int EC_POINT_get_Jprojective_coordinates_GFp(const EC_GROUP *group,
|
|
const EC_POINT *p,
|
|
BIGNUM *x, BIGNUM *y, BIGNUM *z,
|
|
BN_CTX *ctx);
|
|
int EC_POINT_set_affine_coordinates(const EC_GROUP *group, EC_POINT *p,
|
|
const BIGNUM *x, const BIGNUM *y,
|
|
BN_CTX *ctx);
|
|
int EC_POINT_get_affine_coordinates(const EC_GROUP *group, const EC_POINT *p,
|
|
BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
|
|
int EC_POINT_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *p,
|
|
const BIGNUM *x, int y_bit,
|
|
BN_CTX *ctx);
|
|
int EC_POINT_set_affine_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
|
|
const BIGNUM *x, const BIGNUM *y,
|
|
BN_CTX *ctx);
|
|
int EC_POINT_get_affine_coordinates_GFp(const EC_GROUP *group,
|
|
const EC_POINT *p,
|
|
BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
|
|
int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group,
|
|
EC_POINT *p,
|
|
const BIGNUM *x, int y_bit,
|
|
BN_CTX *ctx);
|
|
int EC_POINT_set_affine_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p,
|
|
const BIGNUM *x, const BIGNUM *y,
|
|
BN_CTX *ctx);
|
|
int EC_POINT_get_affine_coordinates_GF2m(const EC_GROUP *group,
|
|
const EC_POINT *p,
|
|
BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
|
|
int EC_POINT_set_compressed_coordinates_GF2m(const EC_GROUP *group,
|
|
EC_POINT *p,
|
|
const BIGNUM *x, int y_bit,
|
|
BN_CTX *ctx);
|
|
size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *p,
|
|
point_conversion_form_t form,
|
|
unsigned char *buf, size_t len, BN_CTX *ctx);
|
|
size_t EC_POINT_point2buf(const EC_GROUP *group, const EC_POINT *point,
|
|
point_conversion_form_t form,
|
|
unsigned char **pbuf, BN_CTX *ctx);
|
|
int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *p,
|
|
const unsigned char *buf, size_t len, BN_CTX *ctx);
|
|
BIGNUM *EC_POINT_point2bn(const EC_GROUP *group, const EC_POINT *p,
|
|
point_conversion_form_t form, BIGNUM *bn,
|
|
BN_CTX *ctx);
|
|
EC_POINT *EC_POINT_bn2point(const EC_GROUP *group, const BIGNUM *bn,
|
|
EC_POINT *p, BN_CTX *ctx);
|
|
char *EC_POINT_point2hex(const EC_GROUP *group, const EC_POINT *p,
|
|
point_conversion_form_t form, BN_CTX *ctx);
|
|
EC_POINT *EC_POINT_hex2point(const EC_GROUP *group, const char *hex,
|
|
EC_POINT *p, BN_CTX *ctx);
|
|
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
An B<EC_POINT> structure represents a point on a curve. A new point is
|
|
constructed by calling the function EC_POINT_new() and providing the
|
|
B<group> object that the point relates to.
|
|
|
|
EC_POINT_free() frees the memory associated with the B<EC_POINT>.
|
|
if B<point> is NULL nothing is done.
|
|
|
|
EC_POINT_clear_free() destroys any sensitive data held within the EC_POINT and
|
|
then frees its memory. If B<point> is NULL nothing is done.
|
|
|
|
EC_POINT_copy() copies the point B<src> into B<dst>. Both B<src> and B<dst>
|
|
must use the same B<EC_METHOD>.
|
|
|
|
EC_POINT_dup() creates a new B<EC_POINT> object and copies the content from
|
|
B<src> to the newly created B<EC_POINT> object.
|
|
|
|
EC_POINT_method_of() obtains the B<EC_METHOD> associated with B<point>.
|
|
|
|
A valid point on a curve is the special point at infinity. A point is set to
|
|
be at infinity by calling EC_POINT_set_to_infinity().
|
|
|
|
The affine co-ordinates for a point describe a point in terms of its x and y
|
|
position. The function EC_POINT_set_affine_coordinates() sets the B<x> and B<y>
|
|
co-ordinates for the point B<p> defined over the curve given in B<group>. The
|
|
function EC_POINT_get_affine_coordinates() sets B<x> and B<y>, either of which
|
|
may be NULL, to the corresponding coordinates of B<p>.
|
|
|
|
The functions EC_POINT_set_affine_coordinates_GFp() and
|
|
EC_POINT_set_affine_coordinates_GF2m() are synonyms for
|
|
EC_POINT_set_affine_coordinates(). They are defined for backwards compatibility
|
|
only and should not be used.
|
|
|
|
The functions EC_POINT_get_affine_coordinates_GFp() and
|
|
EC_POINT_get_affine_coordinates_GF2m() are synonyms for
|
|
EC_POINT_get_affine_coordinates(). They are defined for backwards compatibility
|
|
only and should not be used.
|
|
|
|
As well as the affine co-ordinates, a point can alternatively be described in
|
|
terms of its Jacobian projective co-ordinates (for Fp curves only). Jacobian
|
|
projective co-ordinates are expressed as three values x, y and z. Working in
|
|
this co-ordinate system provides more efficient point multiplication
|
|
operations. A mapping exists between Jacobian projective co-ordinates and
|
|
affine co-ordinates. A Jacobian projective co-ordinate (x, y, z) can be written
|
|
as an affine co-ordinate as (x/(z^2), y/(z^3)). Conversion to Jacobian
|
|
projective from affine co-ordinates is simple. The co-ordinate (x, y) is mapped
|
|
to (x, y, 1). To set or get the projective co-ordinates use
|
|
EC_POINT_set_Jprojective_coordinates_GFp() and
|
|
EC_POINT_get_Jprojective_coordinates_GFp() respectively.
|
|
|
|
Points can also be described in terms of their compressed co-ordinates. For a
|
|
point (x, y), for any given value for x such that the point is on the curve
|
|
there will only ever be two possible values for y. Therefore a point can be set
|
|
using the EC_POINT_set_compressed_coordinates() function where B<x> is the x
|
|
co-ordinate and B<y_bit> is a value 0 or 1 to identify which of the two
|
|
possible values for y should be used.
|
|
|
|
The functions EC_POINT_set_compressed_coordinates_GFp() and
|
|
EC_POINT_set_compressed_coordinates_GF2m() are synonyms for
|
|
EC_POINT_set_compressed_coordinates(). They are defined for backwards
|
|
compatibility only and should not be used.
|
|
|
|
In addition B<EC_POINT> can be converted to and from various external
|
|
representations. The octet form is the binary encoding of the B<ECPoint>
|
|
structure (as defined in RFC5480 and used in certificates and TLS records):
|
|
only the content octets are present, the B<OCTET STRING> tag and length are
|
|
not included. B<BIGNUM> form is the octet form interpreted as a big endian
|
|
integer converted to a B<BIGNUM> structure. Hexadecimal form is the octet
|
|
form converted to a NULL terminated character string where each character
|
|
is one of the printable values 0-9 or A-F (or a-f).
|
|
|
|
The functions EC_POINT_point2oct(), EC_POINT_oct2point(), EC_POINT_point2bn(),
|
|
EC_POINT_bn2point(), EC_POINT_point2hex() and EC_POINT_hex2point() convert from
|
|
and to EC_POINTs for the formats: octet, BIGNUM and hexadecimal respectively.
|
|
|
|
The function EC_POINT_point2oct() must be supplied with a buffer long enough to
|
|
store the octet form. The return value provides the number of octets stored.
|
|
Calling the function with a NULL buffer will not perform the conversion but
|
|
will still return the required buffer length.
|
|
|
|
The function EC_POINT_point2buf() allocates a buffer of suitable length and
|
|
writes an EC_POINT to it in octet format. The allocated buffer is written to
|
|
B<*pbuf> and its length is returned. The caller must free up the allocated
|
|
buffer with a call to OPENSSL_free(). Since the allocated buffer value is
|
|
written to B<*pbuf> the B<pbuf> parameter B<MUST NOT> be B<NULL>.
|
|
|
|
The function EC_POINT_point2hex() will allocate sufficient memory to store the
|
|
hexadecimal string. It is the caller's responsibility to free this memory with
|
|
a subsequent call to OPENSSL_free().
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
EC_POINT_new() and EC_POINT_dup() return the newly allocated EC_POINT or NULL
|
|
on error.
|
|
|
|
The following functions return 1 on success or 0 on error: EC_POINT_copy(),
|
|
EC_POINT_set_to_infinity(), EC_POINT_set_Jprojective_coordinates_GFp(),
|
|
EC_POINT_get_Jprojective_coordinates_GFp(),
|
|
EC_POINT_set_affine_coordinates_GFp(), EC_POINT_get_affine_coordinates_GFp(),
|
|
EC_POINT_set_compressed_coordinates_GFp(),
|
|
EC_POINT_set_affine_coordinates_GF2m(), EC_POINT_get_affine_coordinates_GF2m(),
|
|
EC_POINT_set_compressed_coordinates_GF2m() and EC_POINT_oct2point().
|
|
|
|
EC_POINT_method_of returns the EC_METHOD associated with the supplied EC_POINT.
|
|
|
|
EC_POINT_point2oct() and EC_POINT_point2buf() return the length of the required
|
|
buffer or 0 on error.
|
|
|
|
EC_POINT_point2bn() returns the pointer to the BIGNUM supplied, or NULL on
|
|
error.
|
|
|
|
EC_POINT_bn2point() returns the pointer to the EC_POINT supplied, or NULL on
|
|
error.
|
|
|
|
EC_POINT_point2hex() returns a pointer to the hex string, or NULL on error.
|
|
|
|
EC_POINT_hex2point() returns the pointer to the EC_POINT supplied, or NULL on
|
|
error.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<crypto(7)>, L<EC_GROUP_new(3)>, L<EC_GROUP_copy(3)>,
|
|
L<EC_POINT_add(3)>, L<EC_KEY_new(3)>,
|
|
L<EC_GFp_simple_method(3)>, L<d2i_ECPKParameters(3)>
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
Licensed under the Apache License 2.0 (the "License"). You may not use
|
|
this file except in compliance with the License. You can obtain a copy
|
|
in the file LICENSE in the source distribution or at
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|