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.\" $OpenBSD: EC_POINT_new.3,v 1.18 2025/04/25 19:57:12 tb Exp $
.\"
.\" Copyright (c) 2025 Theo Buehler <tb@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: April 25 2025 $
.Dt EC_POINT_NEW 3
.Os
.Sh NAME
.Nm EC_POINT_new ,
.Nm EC_POINT_free ,
.Nm EC_POINT_clear_free ,
.Nm EC_POINT_copy ,
.Nm EC_POINT_dup
.Nd allocate, free and copy elliptic curve points
.Sh SYNOPSIS
.In openssl/ec.h
.Pp
.Ft "EC_POINT *"
.Fo EC_POINT_new
.Fa "const EC_GROUP *group"
.Fc
.Ft "void"
.Fo EC_POINT_free
.Fa "EC_POINT *point"
.Fc
.Ft "void"
.Fo EC_POINT_clear_free
.Fa "EC_POINT *point"
.Fc
.Ft "int"
.Fo EC_POINT_copy
.Fa "EC_POINT *dst"
.Fa "const EC_POINT *src"
.Fc
.Ft "EC_POINT *"
.Fo EC_POINT_dup
.Fa "const EC_POINT *point"
.Fa "const EC_GROUP *group"
.Fc
.Sh DESCRIPTION
An
.Vt EC_POINT
object holds a point on the elliptic curve represented by an
.Vt EC_GROUP .
The details of the internal representation depend on the group
and should never be an application's concern since the EC library
has API to set a point's coordinates,
.Xr EC_POINT_set_affine_coordinates 3 .
.Pp
.Fn EC_POINT_new
allocates and initializes an
.Vt EC_POINT
object to be used with the
.Fa group .
Before explicitly setting its coordinates, the returned
.Vt EC_POINT
is invalid.
.Pp
.Fn EC_POINT_free
frees
.Fa point
and all memory associated with it.
If
.Fa point
is a
.Dv NULL
pointer, no action occurs.
.Pp
.Fn EC_POINT_clear_free
is intended to destroy sensitive data held in
.Fa point
in addition to freeing all memory associated with it.
Since elliptic curve points usually hold public data, this
is rarely needed.
In LibreSSL,
.Fn EC_POINT_free
and
.Fn EC_POINT_clear_free
behave identically.
.Pp
.Fn EC_POINT_copy
copies the internal representation of
.Fa src
into
.Fa dst .
If
.Fa src
and
.Fa dst
are identical, no action occurs.
Both
.Fa src
and
.Fa dst
should be the result of
.Fn EC_POINT_new
with the same
.Fa group
argument, although
.Fn EC_POINT_copy
cannot check that.
.Pp
.Fn EC_POINT_dup
creates a deep copy of
.Fa point
by combining
.Fn EC_POINT_new
with
.Fn EC_GROUP_copy .
.Sh RETURN VALUES
.Fn EC_POINT_new
returns a newly allocated
.Vt EC_POINT
or
.Dv NULL
on memory allocation failure.
.Pp
.Fn EC_POINT_copy
returns 1 on success or 0 on error.
Error conditions include memory allocation failure and that
.Fa dst
is incompatible with the group on which
.Fa src
is defined.
.Pp
.Fn EC_POINT_dup
returns a newly allocated
.Vt EC_POINT
or
.Dv NULL
on failure.
Error conditions include memory allocation failure or that
.Fa group
is incompatible with
.Fa src .
.Sh SEE ALSO
.Xr BN_CTX_new 3 ,
.Xr BN_is_zero 3 ,
.Xr crypto 3 ,
.Xr d2i_ECPKParameters 3 ,
.Xr EC_GROUP_check 3 ,
.Xr EC_GROUP_get_curve_name 3 ,
.Xr EC_GROUP_new_by_curve_name 3 ,
.Xr EC_GROUP_new_curve_GFp 3 ,
.Xr EC_KEY_METHOD_new 3 ,
.Xr EC_KEY_new 3 ,
.Xr EC_POINT_add 3 ,
.Xr EC_POINT_get_affine_coordinates 3 ,
.Xr EC_POINT_point2oct 3 ,
.Xr ECDH_compute_key 3 ,
.Xr ECDSA_SIG_new 3
.Sh HISTORY
.Fn EC_POINT_new ,
.Fn EC_POINT_free ,
.Fn EC_POINT_clear_free ,
and
.Fn EC_POINT_copy
first appeared in OpenSSL 0.9.7 and have been available since
.Ox 3.2 .
.Pp
.Fn EC_POINT_dup
first appeared in OpenSSL 0.9.8 and has been available since
.Ox 4.5 .
.Sh BUGS
A fundamental flaw in the OpenSSL API toolkit is that
.Fn *_new
functions usually create invalid objects that are tricky to
turn into valid objects.
A fundamental flaw in the EC library is that
.Vt EC_POINT
objects do not hold a reference to the group they live on
despite the fact that
.Fn EC_POINT_new
has a
.Fa group
argument.
This is difficult to fix because
.Vt EC_GROUP
objects are not reference counted and
because of const qualifiers in the API.
This is the root cause for various contortions in the EC library
and API.
This has security implications because not
only does the library not know whether an
.Fa EC_POINT
object represents a valid point,
even if it did know that it would not know on what curve.
.Pp
The signature of
.Fn EC_GROUP_dup
is bizarre and the order of
.Fa point
and
.Fa group
is inconsistent with the rest of the EC API.
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