.\" -*- mode: troff; coding: utf-8 -*- .\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. .ie n \{\ . ds C` "" . ds C' "" 'br\} .el\{\ . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" ======================================================================== .\" .IX Title "EC_POINT_NEW 3SSL" .TH EC_POINT_NEW 3SSL 2024-04-04 3.2.2-dev OpenSSL .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH 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 .SH SYNOPSIS .IX Header "SYNOPSIS" .Vb 1 \& #include \& \& 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); \& int EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point); \& 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); \& 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); \& 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); .Ve .PP The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining \fBOPENSSL_API_COMPAT\fR with a suitable version value, see \fBopenssl_user_macros\fR\|(7): .PP .Vb 10 \& const EC_METHOD *EC_POINT_method_of(const 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_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); \& 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); .Ve .SH DESCRIPTION .IX Header "DESCRIPTION" An \fBEC_POINT\fR structure represents a point on a curve. A new point is constructed by calling the function \fBEC_POINT_new()\fR and providing the \&\fBgroup\fR object that the point relates to. .PP \&\fBEC_POINT_free()\fR frees the memory associated with the \fBEC_POINT\fR. if \fBpoint\fR is NULL nothing is done. .PP \&\fBEC_POINT_clear_free()\fR destroys any sensitive data held within the EC_POINT and then frees its memory. If \fBpoint\fR is NULL nothing is done. .PP \&\fBEC_POINT_copy()\fR copies the point \fBsrc\fR into \fBdst\fR. Both \fBsrc\fR and \fBdst\fR must use the same \fBEC_METHOD\fR. .PP \&\fBEC_POINT_dup()\fR creates a new \fBEC_POINT\fR object and copies the content from \&\fBsrc\fR to the newly created \fBEC_POINT\fR object. .PP \&\fBEC_POINT_method_of()\fR obtains the \fBEC_METHOD\fR associated with \fBpoint\fR. This function was deprecated in OpenSSL 3.0, since EC_METHOD is no longer a public concept. .PP A valid point on a curve is the special point at infinity. A point is set to be at infinity by calling \fBEC_POINT_set_to_infinity()\fR. .PP The affine coordinates for a point describe a point in terms of its x and y position. The function \fBEC_POINT_set_affine_coordinates()\fR sets the \fBx\fR and \fBy\fR coordinates for the point \fBp\fR defined over the curve given in \fBgroup\fR. The function \fBEC_POINT_get_affine_coordinates()\fR sets \fBx\fR and \fBy\fR, either of which may be NULL, to the corresponding coordinates of \fBp\fR. .PP The functions \fBEC_POINT_set_affine_coordinates_GFp()\fR and \&\fBEC_POINT_set_affine_coordinates_GF2m()\fR are synonyms for \&\fBEC_POINT_set_affine_coordinates()\fR. They are defined for backwards compatibility only and should not be used. .PP The functions \fBEC_POINT_get_affine_coordinates_GFp()\fR and \&\fBEC_POINT_get_affine_coordinates_GF2m()\fR are synonyms for \&\fBEC_POINT_get_affine_coordinates()\fR. They are defined for backwards compatibility only and should not be used. .PP As well as the affine coordinates, a point can alternatively be described in terms of its Jacobian projective coordinates (for Fp curves only). Jacobian projective coordinates are expressed as three values x, y and z. Working in this coordinate system provides more efficient point multiplication operations. A mapping exists between Jacobian projective coordinates and affine coordinates. A Jacobian projective coordinate (x, y, z) can be written as an affine coordinate as (x/(z^2), y/(z^3)). Conversion to Jacobian projective from affine coordinates is simple. The coordinate (x, y) is mapped to (x, y, 1). Although deprecated in OpenSSL 3.0 and should no longer be used, to set or get the projective coordinates in older versions use \&\fBEC_POINT_set_Jprojective_coordinates_GFp()\fR and \&\fBEC_POINT_get_Jprojective_coordinates_GFp()\fR respectively. Modern versions should instead use \fBEC_POINT_set_affine_coordinates()\fR and \&\fBEC_POINT_get_affine_coordinates()\fR, performing the conversion manually using the above maps in such rare circumstances. .PP Points can also be described in terms of their compressed coordinates. 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 \fBEC_POINT_set_compressed_coordinates()\fR function where \fBx\fR is the x coordinate and \fBy_bit\fR is a value 0 or 1 to identify which of the two possible values for y should be used. .PP The functions \fBEC_POINT_set_compressed_coordinates_GFp()\fR and \&\fBEC_POINT_set_compressed_coordinates_GF2m()\fR are synonyms for \&\fBEC_POINT_set_compressed_coordinates()\fR. They are defined for backwards compatibility only and should not be used. .PP In addition \fBEC_POINT\fR can be converted to and from various external representations. The octet form is the binary encoding of the \fBECPoint\fR structure (as defined in RFC5480 and used in certificates and TLS records): only the content octets are present, the \fBOCTET STRING\fR tag and length are not included. \fBBIGNUM\fR form is the octet form interpreted as a big endian integer converted to a \fBBIGNUM\fR 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). .PP The functions \fBEC_POINT_point2oct()\fR, \fBEC_POINT_oct2point()\fR, \fBEC_POINT_point2bn()\fR, \&\fBEC_POINT_bn2point()\fR, \fBEC_POINT_point2hex()\fR and \fBEC_POINT_hex2point()\fR convert from and to EC_POINTs for the formats: octet, BIGNUM and hexadecimal respectively. .PP The function \fBEC_POINT_point2oct()\fR encodes the given curve point \fBp\fR as an octet string into the buffer \fBbuf\fR of size \fBlen\fR, using the specified conversion form \fBform\fR. The encoding conforms with Sec. 2.3.3 of the SECG SEC 1 ("Elliptic Curve Cryptography") standard. Similarly the function \fBEC_POINT_oct2point()\fR decodes a curve point into \fBp\fR from the octet string contained in the given buffer \fBbuf\fR of size \fBlen\fR, conforming to Sec. 2.3.4 of the SECG SEC 1 ("Elliptic Curve Cryptography") standard. .PP The functions \fBEC_POINT_point2hex()\fR and \fBEC_POINT_point2bn()\fR convert a point \fBp\fR, respectively, to the hexadecimal or BIGNUM representation of the same encoding of the function \fBEC_POINT_point2oct()\fR. Vice versa, similarly to the function \fBEC_POINT_oct2point()\fR, the functions \&\fBEC_POINT_hex2point()\fR and \fBEC_POINT_point2bn()\fR decode the hexadecimal or BIGNUM representation into the EC_POINT \fBp\fR. .PP Notice that, according to the standard, the octet string encoding of the point at infinity for a given curve is fixed to a single octet of value zero and that, vice versa, a single octet of size zero is decoded as the point at infinity. .PP The function \fBEC_POINT_point2oct()\fR 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. .PP The function \fBEC_POINT_point2buf()\fR allocates a buffer of suitable length and writes an EC_POINT to it in octet format. The allocated buffer is written to \&\fB*pbuf\fR and its length is returned. The caller must free up the allocated buffer with a call to \fBOPENSSL_free()\fR. Since the allocated buffer value is written to \fB*pbuf\fR the \fBpbuf\fR parameter \fBMUST NOT\fR be \fBNULL\fR. .PP The function \fBEC_POINT_point2hex()\fR will allocate sufficient memory to store the hexadecimal string. It is the caller's responsibility to free this memory with a subsequent call to \fBOPENSSL_free()\fR. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBEC_POINT_new()\fR and \fBEC_POINT_dup()\fR return the newly allocated EC_POINT or NULL on error. .PP The following functions return 1 on success or 0 on error: \fBEC_POINT_copy()\fR, \&\fBEC_POINT_set_to_infinity()\fR, \fBEC_POINT_set_Jprojective_coordinates_GFp()\fR, \&\fBEC_POINT_get_Jprojective_coordinates_GFp()\fR, \&\fBEC_POINT_set_affine_coordinates_GFp()\fR, \fBEC_POINT_get_affine_coordinates_GFp()\fR, \&\fBEC_POINT_set_compressed_coordinates_GFp()\fR, \&\fBEC_POINT_set_affine_coordinates_GF2m()\fR, \fBEC_POINT_get_affine_coordinates_GF2m()\fR, \&\fBEC_POINT_set_compressed_coordinates_GF2m()\fR and \fBEC_POINT_oct2point()\fR. .PP EC_POINT_method_of returns the EC_METHOD associated with the supplied EC_POINT. .PP \&\fBEC_POINT_point2oct()\fR and \fBEC_POINT_point2buf()\fR return the length of the required buffer or 0 on error. .PP \&\fBEC_POINT_point2bn()\fR returns the pointer to the BIGNUM supplied, or NULL on error. .PP \&\fBEC_POINT_bn2point()\fR returns the pointer to the EC_POINT supplied, or NULL on error. .PP \&\fBEC_POINT_point2hex()\fR returns a pointer to the hex string, or NULL on error. .PP \&\fBEC_POINT_hex2point()\fR returns the pointer to the EC_POINT supplied, or NULL on error. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBcrypto\fR\|(7), \fBEC_GROUP_new\fR\|(3), \fBEC_GROUP_copy\fR\|(3), \&\fBEC_POINT_add\fR\|(3), \fBEC_KEY_new\fR\|(3), \&\fBEC_GFp_simple_method\fR\|(3), \fBd2i_ECPKParameters\fR\|(3) .SH HISTORY .IX Header "HISTORY" \&\fBEC_POINT_method_of()\fR, \&\fBEC_POINT_set_Jprojective_coordinates_GFp()\fR, \&\fBEC_POINT_get_Jprojective_coordinates_GFp()\fR, \&\fBEC_POINT_set_affine_coordinates_GFp()\fR, \fBEC_POINT_get_affine_coordinates_GFp()\fR, \&\fBEC_POINT_set_compressed_coordinates_GFp()\fR, \&\fBEC_POINT_set_affine_coordinates_GF2m()\fR, \fBEC_POINT_get_affine_coordinates_GF2m()\fR, \&\fBEC_POINT_set_compressed_coordinates_GF2m()\fR, \&\fBEC_POINT_point2bn()\fR, and \fBEC_POINT_bn2point()\fR were deprecated in OpenSSL 3.0. .PP \&\fBEC_POINT_set_affine_coordinates\fR, \fBEC_POINT_get_affine_coordinates\fR, and \fBEC_POINT_set_compressed_coordinates\fR were added in OpenSSL 1.1.1. .SH COPYRIGHT .IX Header "COPYRIGHT" Copyright 2013\-2023 The OpenSSL Project Authors. All Rights Reserved. .PP 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 .