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✏️ Editing: EC_KEY_generate_key.3

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.\" ========================================================================
.\"
.IX Title "EC_KEY_NEW 3"
.TH EC_KEY_NEW 3 "2023-09-11" "1.1.1w" "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_KEY_get_method, EC_KEY_set_method, EC_KEY_new, EC_KEY_get_flags, EC_KEY_set_flags, EC_KEY_clear_flags, EC_KEY_new_by_curve_name, EC_KEY_free, EC_KEY_copy, EC_KEY_dup, EC_KEY_up_ref, EC_KEY_get0_engine, EC_KEY_get0_group, EC_KEY_set_group, EC_KEY_get0_private_key, EC_KEY_set_private_key, EC_KEY_get0_public_key, EC_KEY_set_public_key, EC_KEY_get_conv_form, EC_KEY_set_conv_form, EC_KEY_set_asn1_flag, EC_KEY_decoded_from_explicit_params, EC_KEY_precompute_mult, EC_KEY_generate_key, EC_KEY_check_key, EC_KEY_set_public_key_affine_coordinates, EC_KEY_oct2key, EC_KEY_key2buf, EC_KEY_oct2priv, EC_KEY_priv2oct, EC_KEY_priv2buf \- Functions for creating, destroying and manipulating EC_KEY objects
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ec.h>
\&
\& EC_KEY *EC_KEY_new(void);
\& int EC_KEY_get_flags(const EC_KEY *key);
\& void EC_KEY_set_flags(EC_KEY *key, int flags);
\& void EC_KEY_clear_flags(EC_KEY *key, int flags);
\& EC_KEY *EC_KEY_new_by_curve_name(int nid);
\& void EC_KEY_free(EC_KEY *key);
\& EC_KEY *EC_KEY_copy(EC_KEY *dst, const EC_KEY *src);
\& EC_KEY *EC_KEY_dup(const EC_KEY *src);
\& int EC_KEY_up_ref(EC_KEY *key);
\& ENGINE *EC_KEY_get0_engine(const EC_KEY *eckey);
\& const EC_GROUP *EC_KEY_get0_group(const EC_KEY *key);
\& int EC_KEY_set_group(EC_KEY *key, const EC_GROUP *group);
\& const BIGNUM *EC_KEY_get0_private_key(const EC_KEY *key);
\& int EC_KEY_set_private_key(EC_KEY *key, const BIGNUM *priv_key);
\& const EC_POINT *EC_KEY_get0_public_key(const EC_KEY *key);
\& int EC_KEY_set_public_key(EC_KEY *key, const EC_POINT *pub);
\& point_conversion_form_t EC_KEY_get_conv_form(const EC_KEY *key);
\& void EC_KEY_set_conv_form(EC_KEY *eckey, point_conversion_form_t cform);
\& void EC_KEY_set_asn1_flag(EC_KEY *eckey, int asn1_flag);
\& int EC_KEY_decoded_from_explicit_params(const EC_KEY *key);
\& int EC_KEY_precompute_mult(EC_KEY *key, BN_CTX *ctx);
\& int EC_KEY_generate_key(EC_KEY *key);
\& int EC_KEY_check_key(const EC_KEY *key);
\& int EC_KEY_set_public_key_affine_coordinates(EC_KEY *key, BIGNUM *x, BIGNUM *y);
\& const EC_KEY_METHOD *EC_KEY_get_method(const EC_KEY *key);
\& int EC_KEY_set_method(EC_KEY *key, const EC_KEY_METHOD *meth);
\&
\& int EC_KEY_oct2key(EC_KEY *eckey, const unsigned char *buf, size_t len, BN_CTX *ctx);
\& size_t EC_KEY_key2buf(const EC_KEY *eckey, point_conversion_form_t form,
\&                       unsigned char **pbuf, BN_CTX *ctx);
\&
\& int EC_KEY_oct2priv(EC_KEY *eckey, const unsigned char *buf, size_t len);
\& size_t EC_KEY_priv2oct(const EC_KEY *eckey, unsigned char *buf, size_t len);
\&
\& size_t EC_KEY_priv2buf(const EC_KEY *eckey, unsigned char **pbuf);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
An \s-1EC_KEY\s0 represents a public key and, optionally, the associated private
key. A new \s-1EC_KEY\s0 with no associated curve can be constructed by calling
\&\fBEC_KEY_new()\fR. The reference count for the newly created \s-1EC_KEY\s0 is initially
set to 1. A curve can be associated with the \s-1EC_KEY\s0 by calling
\&\fBEC_KEY_set_group()\fR.
.PP
Alternatively a new \s-1EC_KEY\s0 can be constructed by calling
\&\fBEC_KEY_new_by_curve_name()\fR and supplying the nid of the associated curve. See
\&\fBEC_GROUP_new\fR\|(3) for a description of curve names. This function simply
wraps calls to \fBEC_KEY_new()\fR and \fBEC_GROUP_new_by_curve_name()\fR.
.PP
Calling \fBEC_KEY_free()\fR decrements the reference count for the \s-1EC_KEY\s0 object,
and if it has dropped to zero then frees the memory associated with it.  If
\&\fBkey\fR is \s-1NULL\s0 nothing is done.
.PP
\&\fBEC_KEY_copy()\fR copies the contents of the \s-1EC_KEY\s0 in \fBsrc\fR into \fBdest\fR.
.PP
\&\fBEC_KEY_dup()\fR creates a new \s-1EC_KEY\s0 object and copies \fBec_key\fR into it.
.PP
\&\fBEC_KEY_up_ref()\fR increments the reference count associated with the \s-1EC_KEY\s0
object.
.PP
\&\fBEC_KEY_get0_engine()\fR returns a handle to the \s-1ENGINE\s0 that has been set for
this \s-1EC_KEY\s0 object.
.PP
\&\fBEC_KEY_generate_key()\fR generates a new public and private key for the supplied
\&\fBeckey\fR object. \fBeckey\fR must have an \s-1EC_GROUP\s0 object associated with it
before calling this function. The private key is a random integer (0 < priv_key
< order, where \fIorder\fR is the order of the \s-1EC_GROUP\s0 object). The public key is
an \s-1EC_POINT\s0 on the curve calculated by multiplying the generator for the
curve by the private key.
.PP
\&\fBEC_KEY_check_key()\fR performs various sanity checks on the \s-1EC_KEY\s0 object to
confirm that it is valid.
.PP
\&\fBEC_KEY_set_public_key_affine_coordinates()\fR sets the public key for \fBkey\fR based
on its affine co-ordinates; i.e., it constructs an \s-1EC_POINT\s0 object based on
the supplied \fBx\fR and \fBy\fR values and sets the public key to be this
\&\s-1EC_POINT.\s0 It also performs certain sanity checks on the key to confirm
that it is valid.
.PP
The functions \fBEC_KEY_get0_group()\fR, \fBEC_KEY_set_group()\fR,
\&\fBEC_KEY_get0_private_key()\fR, \fBEC_KEY_set_private_key()\fR, \fBEC_KEY_get0_public_key()\fR,
and \fBEC_KEY_set_public_key()\fR get and set the \s-1EC_GROUP\s0 object, the private key,
and the \s-1EC_POINT\s0 public key for the \fBkey\fR respectively. The function
\&\fBEC_KEY_set_private_key()\fR accepts \s-1NULL\s0 as the priv_key argument to securely clear
the private key component from the \s-1EC_KEY.\s0
.PP
The functions \fBEC_KEY_get_conv_form()\fR and \fBEC_KEY_set_conv_form()\fR get and set the
point_conversion_form for the \fBkey\fR. For a description of
point_conversion_forms please see \fBEC_POINT_new\fR\|(3).
.PP
\&\fBEC_KEY_set_flags()\fR sets the flags in the \fBflags\fR parameter on the \s-1EC_KEY\s0
object. Any flags that are already set are left set. The flags currently
defined are \s-1EC_FLAG_NON_FIPS_ALLOW\s0 and \s-1EC_FLAG_FIPS_CHECKED.\s0 In
addition there is the flag \s-1EC_FLAG_COFACTOR_ECDH\s0 which is specific to \s-1ECDH.\s0
\&\fBEC_KEY_get_flags()\fR returns the current flags that are set for this \s-1EC_KEY.\s0
\&\fBEC_KEY_clear_flags()\fR clears the flags indicated by the \fBflags\fR parameter; all
other flags are left in their existing state.
.PP
\&\fBEC_KEY_set_asn1_flag()\fR sets the asn1_flag on the underlying \s-1EC_GROUP\s0 object
(if set). Refer to \fBEC_GROUP_copy\fR\|(3) for further information on the
asn1_flag.
.PP
\&\fBEC_KEY_decoded_from_explicit_params()\fR returns 1 if the group of the \fIkey\fR was
decoded from data with explicitly encoded group parameters, \-1 if the \fIkey\fR
is \s-1NULL\s0 or the group parameters are missing, and 0 otherwise.
.PP
\&\fBEC_KEY_precompute_mult()\fR stores multiples of the underlying \s-1EC_GROUP\s0 generator
for faster point multiplication. See also \fBEC_POINT_add\fR\|(3).
.PP
\&\fBEC_KEY_oct2key()\fR and \fBEC_KEY_key2buf()\fR are identical to the functions
\&\fBEC_POINT_oct2point()\fR and \fBEC_POINT_point2buf()\fR except they use the public key
\&\s-1EC_POINT\s0 in \fBeckey\fR.
.PP
\&\fBEC_KEY_oct2priv()\fR and \fBEC_KEY_priv2oct()\fR convert between the private key
component of \fBeckey\fR and octet form. The octet form consists of the content
octets of the \fBprivateKey\fR \s-1OCTET STRING\s0 in an \fBECPrivateKey\fR \s-1ASN.1\s0 structure.
.PP
The function \fBEC_KEY_priv2oct()\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 \s-1NULL\s0 buffer will not perform the conversion but
will just return the required buffer length.
.PP
The function \fBEC_KEY_priv2buf()\fR allocates a buffer of suitable length and writes
an \s-1EC_KEY\s0 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 \fB\s-1MUST NOT\s0\fR be \fB\s-1NULL\s0\fR.
.PP
\&\fBEC_KEY_priv2buf()\fR converts an \s-1EC_KEY\s0 private key into an allocated buffer.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBEC_KEY_new()\fR, \fBEC_KEY_new_by_curve_name()\fR and \fBEC_KEY_dup()\fR return a pointer to
the newly created \s-1EC_KEY\s0 object, or \s-1NULL\s0 on error.
.PP
\&\fBEC_KEY_get_flags()\fR returns the flags associated with the \s-1EC_KEY\s0 object as an
integer.
.PP
\&\fBEC_KEY_copy()\fR returns a pointer to the destination key, or \s-1NULL\s0 on error.
.PP
\&\fBEC_KEY_get0_engine()\fR returns a pointer to an \s-1ENGINE,\s0 or \s-1NULL\s0 if it wasn't set.
.PP
\&\fBEC_KEY_up_ref()\fR, \fBEC_KEY_set_group()\fR, \fBEC_KEY_set_public_key()\fR,
\&\fBEC_KEY_precompute_mult()\fR, \fBEC_KEY_generate_key()\fR, \fBEC_KEY_check_key()\fR,
\&\fBEC_KEY_set_public_key_affine_coordinates()\fR, \fBEC_KEY_oct2key()\fR and
\&\fBEC_KEY_oct2priv()\fR return 1 on success or 0 on error.
.PP
\&\fBEC_KEY_set_private_key()\fR returns 1 on success or 0 on error except when the
priv_key argument is \s-1NULL,\s0 in that case it returns 0, for legacy compatibility,
and should not be treated as an error.
.PP
\&\fBEC_KEY_get0_group()\fR returns the \s-1EC_GROUP\s0 associated with the \s-1EC_KEY.\s0
.PP
\&\fBEC_KEY_get0_private_key()\fR returns the private key associated with the \s-1EC_KEY.\s0
.PP
\&\fBEC_KEY_get_conv_form()\fR return the point_conversion_form for the \s-1EC_KEY.\s0
.PP
\&\fBEC_KEY_key2buf()\fR, \fBEC_KEY_priv2oct()\fR and \fBEC_KEY_priv2buf()\fR return the length
of the buffer or 0 on error.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBcrypto\fR\|(7), \fBEC_GROUP_new\fR\|(3),
\&\fBEC_GROUP_copy\fR\|(3), \fBEC_POINT_new\fR\|(3),
\&\fBEC_POINT_add\fR\|(3),
\&\fBEC_GFp_simple_method\fR\|(3),
\&\fBd2i_ECPKParameters\fR\|(3)
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2013\-2022 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.

MR SKB