263 lines
14 KiB
HTML
Executable File
263 lines
14 KiB
HTML
Executable File
<?xml version="1.0" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<title>EC_POINT_new</title>
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<meta http-equiv="content-type" content="text/html; charset=utf-8" />
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<link rev="made" href="mailto:root@localhost" />
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</head>
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<body style="background-color: white">
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<!-- INDEX BEGIN -->
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<div name="index">
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<p><a name="__index__"></a></p>
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<ul>
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<li><a href="#name">NAME</a></li>
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<li><a href="#synopsis">SYNOPSIS</a></li>
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<li><a href="#description">DESCRIPTION</a></li>
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<li><a href="#return_values">RETURN VALUES</a></li>
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<li><a href="#see_also">SEE ALSO</a></li>
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<li><a href="#copyright">COPYRIGHT</a></li>
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</ul>
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<hr name="index" />
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</div>
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<!-- INDEX END -->
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<p>
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</p>
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<hr />
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<h1><a name="name">NAME</a></h1>
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<p>EC_POINT_set_Jprojective_coordinates_GFp,
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EC_POINT_point2buf,
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EC_POINT_new,
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EC_POINT_free,
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EC_POINT_clear_free,
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EC_POINT_copy,
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EC_POINT_dup,
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EC_POINT_method_of,
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EC_POINT_set_to_infinity,
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EC_POINT_get_Jprojective_coordinates_GFp,
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EC_POINT_set_affine_coordinates,
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EC_POINT_get_affine_coordinates,
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EC_POINT_set_compressed_coordinates,
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EC_POINT_set_affine_coordinates_GFp,
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EC_POINT_get_affine_coordinates_GFp,
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EC_POINT_set_compressed_coordinates_GFp,
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EC_POINT_set_affine_coordinates_GF2m,
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EC_POINT_get_affine_coordinates_GF2m,
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EC_POINT_set_compressed_coordinates_GF2m,
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EC_POINT_point2oct,
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EC_POINT_oct2point,
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EC_POINT_point2bn,
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EC_POINT_bn2point,
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EC_POINT_point2hex,
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EC_POINT_hex2point
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- Functions for creating, destroying and manipulating EC_POINT objects</p>
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<p>
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</p>
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<hr />
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<h1><a name="synopsis">SYNOPSIS</a></h1>
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<pre>
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#include <openssl/ec.h></pre>
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<pre>
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EC_POINT *EC_POINT_new(const EC_GROUP *group);
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void EC_POINT_free(EC_POINT *point);
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void EC_POINT_clear_free(EC_POINT *point);
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int EC_POINT_copy(EC_POINT *dst, const EC_POINT *src);
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EC_POINT *EC_POINT_dup(const EC_POINT *src, const EC_GROUP *group);
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const EC_METHOD *EC_POINT_method_of(const EC_POINT *point);
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int EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point);
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int EC_POINT_set_Jprojective_coordinates_GFp(const EC_GROUP *group,
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EC_POINT *p,
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const BIGNUM *x, const BIGNUM *y,
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const BIGNUM *z, BN_CTX *ctx);
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int EC_POINT_get_Jprojective_coordinates_GFp(const EC_GROUP *group,
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const EC_POINT *p,
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BIGNUM *x, BIGNUM *y, BIGNUM *z,
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BN_CTX *ctx);
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int EC_POINT_set_affine_coordinates(const EC_GROUP *group, EC_POINT *p,
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const BIGNUM *x, const BIGNUM *y,
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BN_CTX *ctx);
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int EC_POINT_get_affine_coordinates(const EC_GROUP *group, const EC_POINT *p,
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BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
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int EC_POINT_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *p,
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const BIGNUM *x, int y_bit,
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BN_CTX *ctx);
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int EC_POINT_set_affine_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
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const BIGNUM *x, const BIGNUM *y,
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BN_CTX *ctx);
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int EC_POINT_get_affine_coordinates_GFp(const EC_GROUP *group,
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const EC_POINT *p,
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BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
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int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group,
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EC_POINT *p,
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const BIGNUM *x, int y_bit,
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BN_CTX *ctx);
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int EC_POINT_set_affine_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p,
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const BIGNUM *x, const BIGNUM *y,
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BN_CTX *ctx);
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int EC_POINT_get_affine_coordinates_GF2m(const EC_GROUP *group,
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const EC_POINT *p,
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BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
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int EC_POINT_set_compressed_coordinates_GF2m(const EC_GROUP *group,
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EC_POINT *p,
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const BIGNUM *x, int y_bit,
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BN_CTX *ctx);
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size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *p,
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point_conversion_form_t form,
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unsigned char *buf, size_t len, BN_CTX *ctx);
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size_t EC_POINT_point2buf(const EC_GROUP *group, const EC_POINT *point,
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point_conversion_form_t form,
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unsigned char **pbuf, BN_CTX *ctx);
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int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *p,
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const unsigned char *buf, size_t len, BN_CTX *ctx);
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BIGNUM *EC_POINT_point2bn(const EC_GROUP *group, const EC_POINT *p,
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point_conversion_form_t form, BIGNUM *bn,
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BN_CTX *ctx);
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EC_POINT *EC_POINT_bn2point(const EC_GROUP *group, const BIGNUM *bn,
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EC_POINT *p, BN_CTX *ctx);
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char *EC_POINT_point2hex(const EC_GROUP *group, const EC_POINT *p,
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point_conversion_form_t form, BN_CTX *ctx);
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EC_POINT *EC_POINT_hex2point(const EC_GROUP *group, const char *hex,
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EC_POINT *p, BN_CTX *ctx);</pre>
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<p>
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</p>
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<hr />
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<h1><a name="description">DESCRIPTION</a></h1>
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<p>An <strong>EC_POINT</strong> structure represents a point on a curve. A new point is
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constructed by calling the function <code>EC_POINT_new()</code> and providing the
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<strong>group</strong> object that the point relates to.</p>
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<p><code>EC_POINT_free()</code> frees the memory associated with the <strong>EC_POINT</strong>.
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if <strong>point</strong> is NULL nothing is done.</p>
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<p><code>EC_POINT_clear_free()</code> destroys any sensitive data held within the EC_POINT and
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then frees its memory. If <strong>point</strong> is NULL nothing is done.</p>
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<p><code>EC_POINT_copy()</code> copies the point <strong>src</strong> into <strong>dst</strong>. Both <strong>src</strong> and <strong>dst</strong>
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must use the same <strong>EC_METHOD</strong>.</p>
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<p><code>EC_POINT_dup()</code> creates a new <strong>EC_POINT</strong> object and copies the content from
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<strong>src</strong> to the newly created <strong>EC_POINT</strong> object.</p>
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<p><code>EC_POINT_method_of()</code> obtains the <strong>EC_METHOD</strong> associated with <strong>point</strong>.</p>
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<p>A valid point on a curve is the special point at infinity. A point is set to
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be at infinity by calling <code>EC_POINT_set_to_infinity()</code>.</p>
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<p>The affine co-ordinates for a point describe a point in terms of its x and y
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position. The function <code>EC_POINT_set_affine_coordinates()</code> sets the <strong>x</strong> and <strong>y</strong>
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co-ordinates for the point <strong>p</strong> defined over the curve given in <strong>group</strong>. The
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function <code>EC_POINT_get_affine_coordinates()</code> sets <strong>x</strong> and <strong>y</strong>, either of which
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may be NULL, to the corresponding coordinates of <strong>p</strong>.</p>
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<p>The functions <code>EC_POINT_set_affine_coordinates_GFp()</code> and
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EC_POINT_set_affine_coordinates_GF2m() are synonyms for
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<code>EC_POINT_set_affine_coordinates()</code>. They are defined for backwards compatibility
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only and should not be used.</p>
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<p>The functions <code>EC_POINT_get_affine_coordinates_GFp()</code> and
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EC_POINT_get_affine_coordinates_GF2m() are synonyms for
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<code>EC_POINT_get_affine_coordinates()</code>. They are defined for backwards compatibility
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only and should not be used.</p>
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<p>As well as the affine co-ordinates, a point can alternatively be described in
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terms of its Jacobian projective co-ordinates (for Fp curves only). Jacobian
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projective co-ordinates are expressed as three values x, y and z. Working in
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this co-ordinate system provides more efficient point multiplication
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operations. A mapping exists between Jacobian projective co-ordinates and
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affine co-ordinates. A Jacobian projective co-ordinate (x, y, z) can be written
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as an affine co-ordinate as (x/(z^2), y/(z^3)). Conversion to Jacobian
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projective from affine co-ordinates is simple. The co-ordinate (x, y) is mapped
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to (x, y, 1). To set or get the projective co-ordinates use
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<code>EC_POINT_set_Jprojective_coordinates_GFp()</code> and
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<code>EC_POINT_get_Jprojective_coordinates_GFp()</code> respectively.</p>
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<p>Points can also be described in terms of their compressed co-ordinates. For a
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point (x, y), for any given value for x such that the point is on the curve
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there will only ever be two possible values for y. Therefore a point can be set
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using the <code>EC_POINT_set_compressed_coordinates()</code> function where <strong>x</strong> is the x
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co-ordinate and <strong>y_bit</strong> is a value 0 or 1 to identify which of the two
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possible values for y should be used.</p>
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<p>The functions <code>EC_POINT_set_compressed_coordinates_GFp()</code> and
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EC_POINT_set_compressed_coordinates_GF2m() are synonyms for
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<code>EC_POINT_set_compressed_coordinates()</code>. They are defined for backwards
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compatibility only and should not be used.</p>
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<p>In addition <strong>EC_POINT</strong> can be converted to and from various external
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representations. The octet form is the binary encoding of the <strong>ECPoint</strong>
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structure (as defined in <a href="http://www.ietf.org/rfc/rfc5480.txt" class="rfc">RFC5480</a> and used in certificates and TLS records):
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only the content octets are present, the <strong>OCTET STRING</strong> tag and length are
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not included. <strong>BIGNUM</strong> form is the octet form interpreted as a big endian
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integer converted to a <strong>BIGNUM</strong> structure. Hexadecimal form is the octet
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form converted to a NULL terminated character string where each character
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is one of the printable values 0-9 or A-F (or a-f).</p>
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<p>The functions EC_POINT_point2oct(), EC_POINT_oct2point(), EC_POINT_point2bn(),
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EC_POINT_bn2point(), EC_POINT_point2hex() and EC_POINT_hex2point() convert from
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and to EC_POINTs for the formats: octet, BIGNUM and hexadecimal respectively.</p>
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<p>The function EC_POINT_point2oct() encodes the given curve point <strong>p</strong> as an
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octet string into the buffer <strong>buf</strong> of size <strong>len</strong>, using the specified
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conversion form <strong>form</strong>.
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The encoding conforms with Sec. 2.3.3 of the SECG SEC 1 ("Elliptic Curve
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Cryptography") standard.
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Similarly the function EC_POINT_oct2point() decodes a curve point into <strong>p</strong> from
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the octet string contained in the given buffer <strong>buf</strong> of size <strong>len</strong>, conforming
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to Sec. 2.3.4 of the SECG SEC 1 ("Elliptic Curve Cryptography") standard.</p>
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<p>The functions EC_POINT_point2hex() and EC_POINT_point2bn() convert a point <strong>p</strong>,
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respectively, to the hexadecimal or BIGNUM representation of the same
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encoding of the function EC_POINT_point2oct().
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Vice versa, similarly to the function EC_POINT_oct2point(), the functions
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EC_POINT_hex2point() and EC_POINT_point2bn() decode the hexadecimal or
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BIGNUM representation into the EC_POINT <strong>p</strong>.</p>
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<p>Notice that, according to the standard, the octet string encoding of the point
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at infinity for a given curve is fixed to a single octet of value zero and that,
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vice versa, a single octet of size zero is decoded as the point at infinity.</p>
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<p>The function EC_POINT_point2oct() must be supplied with a buffer long enough to
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store the octet form. The return value provides the number of octets stored.
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Calling the function with a NULL buffer will not perform the conversion but
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will still return the required buffer length.</p>
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<p>The function EC_POINT_point2buf() allocates a buffer of suitable length and
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writes an EC_POINT to it in octet format. The allocated buffer is written to
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<strong>*pbuf</strong> and its length is returned. The caller must free up the allocated
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buffer with a call to <code>OPENSSL_free()</code>. Since the allocated buffer value is
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written to <strong>*pbuf</strong> the <strong>pbuf</strong> parameter <strong>MUST NOT</strong> be <strong>NULL</strong>.</p>
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<p>The function EC_POINT_point2hex() will allocate sufficient memory to store the
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hexadecimal string. It is the caller's responsibility to free this memory with
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a subsequent call to <code>OPENSSL_free()</code>.</p>
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<p>
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</p>
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<hr />
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<h1><a name="return_values">RETURN VALUES</a></h1>
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<p><code>EC_POINT_new()</code> and <code>EC_POINT_dup()</code> return the newly allocated EC_POINT or NULL
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on error.</p>
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<p>The following functions return 1 on success or 0 on error: <code>EC_POINT_copy()</code>,
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<code>EC_POINT_set_to_infinity()</code>, <code>EC_POINT_set_Jprojective_coordinates_GFp()</code>,
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<code>EC_POINT_get_Jprojective_coordinates_GFp()</code>,
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<code>EC_POINT_set_affine_coordinates_GFp()</code>, <code>EC_POINT_get_affine_coordinates_GFp()</code>,
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<code>EC_POINT_set_compressed_coordinates_GFp()</code>,
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EC_POINT_set_affine_coordinates_GF2m(), EC_POINT_get_affine_coordinates_GF2m(),
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EC_POINT_set_compressed_coordinates_GF2m() and EC_POINT_oct2point().</p>
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<p>EC_POINT_method_of returns the EC_METHOD associated with the supplied EC_POINT.</p>
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<p>EC_POINT_point2oct() and EC_POINT_point2buf() return the length of the required
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buffer or 0 on error.</p>
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<p>EC_POINT_point2bn() returns the pointer to the BIGNUM supplied, or NULL on
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error.</p>
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<p>EC_POINT_bn2point() returns the pointer to the EC_POINT supplied, or NULL on
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error.</p>
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<p>EC_POINT_point2hex() returns a pointer to the hex string, or NULL on error.</p>
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<p>EC_POINT_hex2point() returns the pointer to the EC_POINT supplied, or NULL on
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error.</p>
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<p>
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</p>
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<hr />
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<h1><a name="see_also">SEE ALSO</a></h1>
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<p><em>crypto(7)</em>, <em>EC_GROUP_new(3)</em>, <em>EC_GROUP_copy(3)</em>,
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<em>EC_POINT_add(3)</em>, <em>EC_KEY_new(3)</em>,
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<em>EC_GFp_simple_method(3)</em>, <em>d2i_ECPKParameters(3)</em></p>
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<p>
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</p>
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<hr />
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<h1><a name="copyright">COPYRIGHT</a></h1>
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<p>Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved.</p>
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<p>Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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<a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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</body>
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</html>
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