.\" $OpenBSD: EC_KEY_METHOD_new.3,v 1.3 2023/08/29 10:07:42 tb Exp $
.\" Copyright (c) 2019 Ingo Schwarze <schwarze@openbsd.org>
.\"
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.\" purpose with or without fee is hereby granted, provided that the above
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.Dd $Mdocdate: August 29 2023 $
.Dt EC_KEY_METHOD_NEW 3
.Os
.Sh NAME
.Nm EC_KEY_METHOD_new ,
.Nm EC_KEY_METHOD_free ,
.Nm EC_KEY_METHOD_set_init ,
.Nm EC_KEY_METHOD_get_init ,
.Nm EC_KEY_METHOD_set_sign ,
.Nm EC_KEY_METHOD_get_sign ,
.Nm EC_KEY_METHOD_set_verify ,
.Nm EC_KEY_METHOD_get_verify ,
.Nm EC_KEY_METHOD_set_keygen ,
.Nm EC_KEY_METHOD_get_keygen ,
.Nm EC_KEY_METHOD_set_compute_key ,
.Nm EC_KEY_METHOD_get_compute_key ,
.Nm EC_KEY_OpenSSL ,
.Nm EC_KEY_set_default_method ,
.Nm EC_KEY_get_default_method ,
.Nm EC_KEY_new_method ,
.Nm EC_KEY_set_method ,
.Nm EC_KEY_get_method
.Nd custom EC_KEY implementations
.Sh SYNOPSIS
.In openssl/ec.h
.Ft EC_KEY_METHOD *
.Fo EC_KEY_METHOD_new
.Fa "const EC_KEY_METHOD *meth"
.Fc
.Ft void
.Fo EC_KEY_METHOD_free
.Fa "EC_KEY_METHOD *meth"
.Fc
.Ft void
.Fo EC_KEY_METHOD_set_init
.Fa "EC_KEY_METHOD *meth"
.Fa "int (*init)(EC_KEY *key)"
.Fa "void (*finish)(EC_KEY *key)"
.Fa "int (*copy)(EC_KEY *dest, const EC_KEY *src)"
.Fa "int (*set_group)(EC_KEY *key, const EC_GROUP *grp)"
.Fa "int (*set_private)(EC_KEY *key, const BIGNUM *priv_key)"
.Fa "int (*set_public)(EC_KEY *key, const EC_POINT *pub_key)"
.Fc
.Ft void
.Fo EC_KEY_METHOD_get_init
.Fa "const EC_KEY_METHOD *meth"
.Fa "int (**pinit)(EC_KEY *key)"
.Fa "void (**pfinish)(EC_KEY *key)"
.Fa "int (**pcopy)(EC_KEY *dest, const EC_KEY *src)"
.Fa "int (**pset_group)(EC_KEY *key, const EC_GROUP *grp)"
.Fa "int (**pset_private)(EC_KEY *key, const BIGNUM *priv_key)"
.Fa "int (**pset_public)(EC_KEY *key, const EC_POINT *pub_key)"
.Fc
.Ft void
.Fo EC_KEY_METHOD_set_sign
.Fa "EC_KEY_METHOD *meth"
.Fa "int (*sign)(int type, const unsigned char *dgst, int dgstlen,\
 unsigned char *sig, unsigned int *siglen,\
 const BIGNUM *kinv, const BIGNUM *r, EC_KEY *eckey)"
.Fa "int (*sign_setup)(EC_KEY *eckey, BN_CTX *ctx,\
 BIGNUM **kinv, BIGNUM **rp)"
.Fa "ECDSA_SIG *(*sign_sig)(const unsigned char *dgst, int dgstlen,\
 const BIGNUM *kinv, const BIGNUM *rp, EC_KEY *eckey)"
.Fc
.Ft void
.Fo EC_KEY_METHOD_get_sign
.Fa "const EC_KEY_METHOD *meth"
.Fa "int (**psign)(int type, const unsigned char *dgst, int dgstlen,\
 unsigned char *sig, unsigned int *siglen,\
 const BIGNUM *kinv, const BIGNUM *r, EC_KEY *eckey)"
.Fa "int (**psign_setup)(EC_KEY *eckey, BN_CTX *ctx,\
 BIGNUM **kinv, BIGNUM **rp)"
.Fa "ECDSA_SIG *(**psign_sig)(const unsigned char *dgst, int dgstlen,\
 const BIGNUM *kinv, const BIGNUM *rp, EC_KEY *eckey)"
.Fc
.Ft void
.Fo EC_KEY_METHOD_set_verify
.Fa "EC_KEY_METHOD *meth"
.Fa "int (*verify)(int type, const unsigned char *dgst, int dgst_len,\
 const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)"
.Fa "int (*verify_sig)(const unsigned char *dgst, int dgst_len,\
 const ECDSA_SIG *sig, EC_KEY *eckey)"
.Fc
.Ft void
.Fo EC_KEY_METHOD_get_verify
.Fa "const EC_KEY_METHOD *meth"
.Fa "int (**pverify)(int type, const unsigned char *dgst, int dgst_len,\
 const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)"
.Fa "int (**pverify_sig)(const unsigned char *dgst, int dgst_len,\
 const ECDSA_SIG *sig, EC_KEY *eckey)"
.Fc
.Ft void
.Fo EC_KEY_METHOD_set_keygen
.Fa "EC_KEY_METHOD *meth"
.Fa "int (*keygen)(EC_KEY *key)"
.Fc
.Ft void
.Fo EC_KEY_METHOD_get_keygen
.Fa "const EC_KEY_METHOD *meth"
.Fa "int (**pkeygen)(EC_KEY *key)"
.Fc
.Ft void
.Fo EC_KEY_METHOD_set_compute_key
.Fa "EC_KEY_METHOD *meth"
.Fa "int (*ckey)(void *out, size_t outlen,\
 const EC_POINT *pub_key, EC_KEY *ecdh,\
 void *(*KDF) (const void *in, size_t inlen, void *out, size_t *outlen))"
.Fc
.Ft void
.Fo EC_KEY_METHOD_get_compute_key
.Fa "const EC_KEY_METHOD *meth"
.Fa "int (**pck)(void *out, size_t outlen,\
 const EC_POINT *pub_key, EC_KEY *ecdh,\
 void *(*KDF) (const void *in, size_t inlen, void *out, size_t *outlen))"
.Fc
.Ft const EC_KEY_METHOD *
.Fn EC_KEY_OpenSSL void
.Ft void
.Fo EC_KEY_set_default_method
.Fa "const EC_KEY_METHOD *meth"
.Fc
.Ft const EC_KEY_METHOD *
.Fn EC_KEY_get_default_method void
.Ft EC_KEY *
.Fo EC_KEY_new_method
.Fa "ENGINE *engine"
.Fc
.Ft int
.Fo EC_KEY_set_method
.Fa "EC_KEY *key"
.Fa "const EC_KEY_METHOD *meth"
.Fc
.Ft const EC_KEY_METHOD *
.Fo EC_KEY_get_method
.Fa "const EC_KEY *key"
.Fc
.Sh DESCRIPTION
An
.Vt EC_KEY_METHOD
object holds function pointers used for
.Vt EC_KEY
operations.
.Pp
.Fn EC_KEY_METHOD_new
creates a shallow copy of
.Fa meth ,
or an empty
.Vt EC_KEY_METHOD
object if
.Fa meth
is
.Dv NULL .
.Pp
.Fn EC_KEY_METHOD_free
frees
.Fa meth .
If
.Fa meth
is
.Dv NULL
or the return value of
.Fn EC_KEY_OpenSSL ,
no action occurs.
.Pp
.Fn EC_KEY_METHOD_set_init
and
.Fn EC_KEY_METHOD_get_init
set and retrieve optional callback functions called at the following places:
.Pp
.Bl -tag -width set_private -compact
.It Fa init
at the end of
.Fn EC_KEY_new_method
and
.Fn EC_KEY_set_method
.It Fa finish
at the beginning of
.Xr EC_KEY_free 3 ,
.Xr EC_KEY_copy 3 ,
and
.Fn EC_KEY_set_method
.It Fa copy
at the end of
.Xr EC_KEY_copy 3
.It Fa set_group
at the end of
.Xr EC_KEY_set_group 3
and
.Xr EC_KEY_new_by_curve_name 3
.It Fa set_private
at the beginning of
.Xr EC_KEY_set_private_key 3
.It Fa set_public
at the beginning of
.Xr EC_KEY_set_public_key 3
.El
.Pp
If any of these callbacks returns 0, the calling function fails.
By default, all these callbacks are
.Dv NULL .
Arguments of
.Fn EC_KEY_METHOD_get_init
can be set to
.Dv NULL
to selectively retrieve callback function pointers.
.Pp
.Fn EC_KEY_METHOD_set_sign
and
.Fn EC_KEY_METHOD_get_sign
set and retrieve the functions implementing
.Xr ECDSA_sign 3
and
.Xr ECDSA_do_sign 3 .
.Pp
.Fn EC_KEY_METHOD_set_verify
and
.Fn EC_KEY_METHOD_get_verify
set and retrieve the functions implementing
.Xr ECDSA_verify 3
and
.Xr ECDSA_do_verify 3 .
.Pp
.Fn EC_KEY_METHOD_set_keygen
and
.Fn EC_KEY_METHOD_get_keygen
set and retrieve the function implementing
.Xr EC_KEY_generate_key 3 .
.Pp
.Fn EC_KEY_METHOD_set_compute_key
and
.Fn EC_KEY_METHOD_get_compute_key
set and retrieve the function implementing
.Xr ECDH_compute_key 3 .
.Pp
.Fn EC_KEY_set_default_method
chooses the
.Fa meth
to be used for the creation of new
.Vt EC_KEY
objects by future invocations of
.Fn EC_KEY_new_method ,
or reverts to the default implementation if
.Fa meth
is
.Dv NULL .
.Pp
.Fn EC_KEY_new_method
creates and initializes a new
.Vt EC_KEY
object using the given
.Fa engine ,
or the using the
.Vt EC_KEY_METHOD
set with
.Fn EC_KEY_set_default_method
if
.Fa engine
is
.Dv NULL ,
or using the default EC_KEY implementation by default.
.Pp
.Fn EC_KEY_set_method
dissociates the
.Fa key
from the
.Vt ENGINE
it is using, if any, and causes it to use
.Fa meth
in the future.
.Sh RETURN VALUES
.Fn EC_KEY_METHOD_new
returns the newly allocated
.Vt EC_KEY_METHOD
object or
.Dv NULL
if an error occurs.
.Pp
.Fn EC_KEY_OpenSSL
returns a static object representing the default EC_KEY implementation.
.Pp
.Fn EC_KEY_get_default_method
returns the
.Vt EC_KEY_METHOD
that
.Fn EC_KEY_new_method
will use for the creation of new
.Vt EC_KEY
objects in the future.
.Pp
.Fn EC_KEY_new_method
returns the newly allocated
.Vt EC_KEY
object or NULL if an error occurs.
.Pp
.Fn EC_KEY_set_method
returns 1 for success or 0 for failure.
.Pp
.Fn EC_KEY_get_method
returns the EC_KEY implementation used by the given
.Fa key .
.Sh SEE ALSO
.Xr EC_KEY_new 3 ,
.Xr ECDSA_sign 3
.Sh HISTORY
These functions first appeared in OpenSSL 1.1.0
and have been available since
.Ox 6.5 .