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131 .IX Title "EC_POINT_NEW 3"
132 .TH EC_POINT_NEW 3 "2018-11-20" "1.1.1a" "OpenSSL"
133 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
134 .\" way too many mistakes in technical documents.
138 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
140 .IX Header "SYNOPSIS"
142 \& #include <openssl/ec.h>
144 \& EC_POINT *EC_POINT_new(const EC_GROUP *group);
145 \& void EC_POINT_free(EC_POINT *point);
146 \& void EC_POINT_clear_free(EC_POINT *point);
147 \& int EC_POINT_copy(EC_POINT *dst, const EC_POINT *src);
148 \& EC_POINT *EC_POINT_dup(const EC_POINT *src, const EC_GROUP *group);
149 \& const EC_METHOD *EC_POINT_method_of(const EC_POINT *point);
150 \& int EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point);
151 \& int EC_POINT_set_Jprojective_coordinates_GFp(const EC_GROUP *group,
153 \& const BIGNUM *x, const BIGNUM *y,
154 \& const BIGNUM *z, BN_CTX *ctx);
155 \& int EC_POINT_get_Jprojective_coordinates_GFp(const EC_GROUP *group,
156 \& const EC_POINT *p,
157 \& BIGNUM *x, BIGNUM *y, BIGNUM *z,
159 \& int EC_POINT_set_affine_coordinates(const EC_GROUP *group, EC_POINT *p,
160 \& const BIGNUM *x, const BIGNUM *y,
162 \& int EC_POINT_get_affine_coordinates(const EC_GROUP *group, const EC_POINT *p,
163 \& BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
164 \& int EC_POINT_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *p,
165 \& const BIGNUM *x, int y_bit,
167 \& int EC_POINT_set_affine_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
168 \& const BIGNUM *x, const BIGNUM *y,
170 \& int EC_POINT_get_affine_coordinates_GFp(const EC_GROUP *group,
171 \& const EC_POINT *p,
172 \& BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
173 \& int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group,
175 \& const BIGNUM *x, int y_bit,
177 \& int EC_POINT_set_affine_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p,
178 \& const BIGNUM *x, const BIGNUM *y,
180 \& int EC_POINT_get_affine_coordinates_GF2m(const EC_GROUP *group,
181 \& const EC_POINT *p,
182 \& BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
183 \& int EC_POINT_set_compressed_coordinates_GF2m(const EC_GROUP *group,
185 \& const BIGNUM *x, int y_bit,
187 \& size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *p,
188 \& point_conversion_form_t form,
189 \& unsigned char *buf, size_t len, BN_CTX *ctx);
190 \& size_t EC_POINT_point2buf(const EC_GROUP *group, const EC_POINT *point,
191 \& point_conversion_form_t form,
192 \& unsigned char **pbuf, BN_CTX *ctx);
193 \& int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *p,
194 \& const unsigned char *buf, size_t len, BN_CTX *ctx);
195 \& BIGNUM *EC_POINT_point2bn(const EC_GROUP *group, const EC_POINT *p,
196 \& point_conversion_form_t form, BIGNUM *bn,
198 \& EC_POINT *EC_POINT_bn2point(const EC_GROUP *group, const BIGNUM *bn,
199 \& EC_POINT *p, BN_CTX *ctx);
200 \& char *EC_POINT_point2hex(const EC_GROUP *group, const EC_POINT *p,
201 \& point_conversion_form_t form, BN_CTX *ctx);
202 \& EC_POINT *EC_POINT_hex2point(const EC_GROUP *group, const char *hex,
203 \& EC_POINT *p, BN_CTX *ctx);
206 .IX Header "DESCRIPTION"
207 An \fB\s-1EC_POINT\s0\fR structure represents a point on a curve. A new point is
208 constructed by calling the function \fIEC_POINT_new()\fR and providing the
209 \&\fBgroup\fR object that the point relates to.
211 \&\fIEC_POINT_free()\fR frees the memory associated with the \fB\s-1EC_POINT\s0\fR.
212 if \fBpoint\fR is \s-1NULL\s0 nothing is done.
214 \&\fIEC_POINT_clear_free()\fR destroys any sensitive data held within the \s-1EC_POINT\s0 and
215 then frees its memory. If \fBpoint\fR is \s-1NULL\s0 nothing is done.
217 \&\fIEC_POINT_copy()\fR copies the point \fBsrc\fR into \fBdst\fR. Both \fBsrc\fR and \fBdst\fR
218 must use the same \fB\s-1EC_METHOD\s0\fR.
220 \&\fIEC_POINT_dup()\fR creates a new \fB\s-1EC_POINT\s0\fR object and copies the content from
221 \&\fBsrc\fR to the newly created \fB\s-1EC_POINT\s0\fR object.
223 \&\fIEC_POINT_method_of()\fR obtains the \fB\s-1EC_METHOD\s0\fR associated with \fBpoint\fR.
225 A valid point on a curve is the special point at infinity. A point is set to
226 be at infinity by calling \fIEC_POINT_set_to_infinity()\fR.
228 The affine co-ordinates for a point describe a point in terms of its x and y
229 position. The function \fIEC_POINT_set_affine_coordinates()\fR sets the \fBx\fR and \fBy\fR
230 co-ordinates for the point \fBp\fR defined over the curve given in \fBgroup\fR. The
231 function \fIEC_POINT_get_affine_coordinates()\fR sets \fBx\fR and \fBy\fR, either of which
232 may be \s-1NULL,\s0 to the corresponding coordinates of \fBp\fR.
234 The functions \fIEC_POINT_set_affine_coordinates_GFp()\fR and
235 \&\fIEC_POINT_set_affine_coordinates_GF2m()\fR are synonyms for
236 \&\fIEC_POINT_set_affine_coordinates()\fR. They are defined for backwards compatibility
237 only and should not be used.
239 The functions \fIEC_POINT_get_affine_coordinates_GFp()\fR and
240 \&\fIEC_POINT_get_affine_coordinates_GF2m()\fR are synonyms for
241 \&\fIEC_POINT_get_affine_coordinates()\fR. They are defined for backwards compatibility
242 only and should not be used.
244 As well as the affine co-ordinates, a point can alternatively be described in
245 terms of its Jacobian projective co-ordinates (for Fp curves only). Jacobian
246 projective co-ordinates are expressed as three values x, y and z. Working in
247 this co-ordinate system provides more efficient point multiplication
248 operations. A mapping exists between Jacobian projective co-ordinates and
249 affine co-ordinates. A Jacobian projective co-ordinate (x, y, z) can be written
250 as an affine co-ordinate as (x/(z^2), y/(z^3)). Conversion to Jacobian
251 projective from affine co-ordinates is simple. The co-ordinate (x, y) is mapped
252 to (x, y, 1). To set or get the projective co-ordinates use
253 \&\fIEC_POINT_set_Jprojective_coordinates_GFp()\fR and
254 \&\fIEC_POINT_get_Jprojective_coordinates_GFp()\fR respectively.
256 Points can also be described in terms of their compressed co-ordinates. For a
257 point (x, y), for any given value for x such that the point is on the curve
258 there will only ever be two possible values for y. Therefore a point can be set
259 using the \fIEC_POINT_set_compressed_coordinates()\fR function where \fBx\fR is the x
260 co-ordinate and \fBy_bit\fR is a value 0 or 1 to identify which of the two
261 possible values for y should be used.
263 The functions \fIEC_POINT_set_compressed_coordinates_GFp()\fR and
264 \&\fIEC_POINT_set_compressed_coordinates_GF2m()\fR are synonyms for
265 \&\fIEC_POINT_set_compressed_coordinates()\fR. They are defined for backwards
266 compatibility only and should not be used.
268 In addition \fB\s-1EC_POINT\s0\fR can be converted to and from various external
269 representations. The octet form is the binary encoding of the \fBECPoint\fR
270 structure (as defined in \s-1RFC5480\s0 and used in certificates and \s-1TLS\s0 records):
271 only the content octets are present, the \fB\s-1OCTET STRING\s0\fR tag and length are
272 not included. \fB\s-1BIGNUM\s0\fR form is the octet form interpreted as a big endian
273 integer converted to a \fB\s-1BIGNUM\s0\fR structure. Hexadecimal form is the octet
274 form converted to a \s-1NULL\s0 terminated character string where each character
275 is one of the printable values 0\-9 or A\-F (or a\-f).
277 The functions \fIEC_POINT_point2oct()\fR, \fIEC_POINT_oct2point()\fR, \fIEC_POINT_point2bn()\fR,
278 \&\fIEC_POINT_bn2point()\fR, \fIEC_POINT_point2hex()\fR and \fIEC_POINT_hex2point()\fR convert from
279 and to EC_POINTs for the formats: octet, \s-1BIGNUM\s0 and hexadecimal respectively.
281 The function \fIEC_POINT_point2oct()\fR must be supplied with a buffer long enough to
282 store the octet form. The return value provides the number of octets stored.
283 Calling the function with a \s-1NULL\s0 buffer will not perform the conversion but
284 will still return the required buffer length.
286 The function \fIEC_POINT_point2buf()\fR allocates a buffer of suitable length and
287 writes an \s-1EC_POINT\s0 to it in octet format. The allocated buffer is written to
288 \&\fB*pbuf\fR and its length is returned. The caller must free up the allocated
289 buffer with a call to \fIOPENSSL_free()\fR. Since the allocated buffer value is
290 written to \fB*pbuf\fR the \fBpbuf\fR parameter \fB\s-1MUST NOT\s0\fR be \fB\s-1NULL\s0\fR.
292 The function \fIEC_POINT_point2hex()\fR will allocate sufficient memory to store the
293 hexadecimal string. It is the caller's responsibility to free this memory with
294 a subsequent call to \fIOPENSSL_free()\fR.
296 .IX Header "RETURN VALUES"
297 \&\fIEC_POINT_new()\fR and \fIEC_POINT_dup()\fR return the newly allocated \s-1EC_POINT\s0 or \s-1NULL\s0
300 The following functions return 1 on success or 0 on error: \fIEC_POINT_copy()\fR,
301 \&\fIEC_POINT_set_to_infinity()\fR, \fIEC_POINT_set_Jprojective_coordinates_GFp()\fR,
302 \&\fIEC_POINT_get_Jprojective_coordinates_GFp()\fR,
303 \&\fIEC_POINT_set_affine_coordinates_GFp()\fR, \fIEC_POINT_get_affine_coordinates_GFp()\fR,
304 \&\fIEC_POINT_set_compressed_coordinates_GFp()\fR,
305 \&\fIEC_POINT_set_affine_coordinates_GF2m()\fR, \fIEC_POINT_get_affine_coordinates_GF2m()\fR,
306 \&\fIEC_POINT_set_compressed_coordinates_GF2m()\fR and \fIEC_POINT_oct2point()\fR.
308 EC_POINT_method_of returns the \s-1EC_METHOD\s0 associated with the supplied \s-1EC_POINT.\s0
310 \&\fIEC_POINT_point2oct()\fR and \fIEC_POINT_point2buf()\fR return the length of the required
311 buffer or 0 on error.
313 \&\fIEC_POINT_point2bn()\fR returns the pointer to the \s-1BIGNUM\s0 supplied, or \s-1NULL\s0 on
316 \&\fIEC_POINT_bn2point()\fR returns the pointer to the \s-1EC_POINT\s0 supplied, or \s-1NULL\s0 on
319 \&\fIEC_POINT_point2hex()\fR returns a pointer to the hex string, or \s-1NULL\s0 on error.
321 \&\fIEC_POINT_hex2point()\fR returns the pointer to the \s-1EC_POINT\s0 supplied, or \s-1NULL\s0 on
324 .IX Header "SEE ALSO"
325 \&\fIcrypto\fR\|(7), \fIEC_GROUP_new\fR\|(3), \fIEC_GROUP_copy\fR\|(3),
326 \&\fIEC_POINT_add\fR\|(3), \fIEC_KEY_new\fR\|(3),
327 \&\fIEC_GFp_simple_method\fR\|(3), \fId2i_ECPKParameters\fR\|(3)
329 .IX Header "COPYRIGHT"
330 Copyright 2013\-2018 The OpenSSL Project Authors. All Rights Reserved.
332 Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use
333 this file except in compliance with the License. You can obtain a copy
334 in the file \s-1LICENSE\s0 in the source distribution or at
335 <https://www.openssl.org/source/license.html>.