.\" $OpenBSD: RSA_get0_key.3,v 1.1 2018/02/17 16:59:48 schwarze Exp $
.\" selective merge up to: OpenSSL 665d899f Aug 2 02:19:43 2017 +0800
.\"
.\" This file was written by Richard Levitte <levitte@openssl.org>
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.Dd $Mdocdate: February 17 2018 $
.Dt RSA_GET0_KEY 3
.Os
.Sh NAME
.Nm RSA_get0_key ,
.Nm RSA_set0_key
.Nd get and set data in an RSA object
.Sh SYNOPSIS
.In openssl/rsa.h
.Ft void
.Fo RSA_get0_key
.Fa "const RSA *r"
.Fa "const BIGNUM **n"
.Fa "const BIGNUM **e"
.Fa "const BIGNUM **d"
.Fc
.Ft int
.Fo RSA_set0_key
.Fa "RSA *r"
.Fa "BIGNUM *n"
.Fa "BIGNUM *e"
.Fa "BIGNUM *d"
.Fc
.Sh DESCRIPTION
An
.Vt RSA
object contains the components for the public and private key.
.Fa n
is the modulus common to both public and private key,
.Fa e
is the public exponent and
.Fa d
is the private exponent.
These parameters can be obtained by calling
.Fn RSA_get0_key .
If they have not been set yet, then
.Pf * Fa n ,
.Pf * Fa e ,
and
.Pf * Fa d
will be set to
.Dv NULL .
Otherwise, they are set to pointers to the internal representations
of the values that should not be freed by the caller.
If any of the arguments is
.Dv NULL ,
the respective parameter is not retrieved.
.Pp
The
.Fa n ,
.Fa e ,
and
.Fa d
parameter values can be set by calling
.Fn RSA_set0_key .
The values
.Fa n
and
.Fa e
must be
.Pf non- Dv NULL
the first time this function is called on a given
.Vt RSA
object.
The value
.Fa d
may be
.Dv NULL .
On subsequent calls, any of these values may be
.Dv NULL ,
which means that the corresponding field is left untouched.
Calling this function transfers the memory management of the values to
the RSA object.
Therefore, the values that have been passed in
should not be freed by the caller.
.Pp
Values retrieved with
.Fn RSA_get0_key
are owned by the
.Vt RSA
object used in the call and may therefore
.Em not
be passed to
.Fn RSA_set0_key .
If needed, duplicate the received value using
.Xr BN_dup 3
and pass the duplicate.
.Sh RETURN VALUES
.Fn RSA_set0_key
returns 1 on success or 0 on failure.
.Sh SEE ALSO
.Xr RSA_check_key 3 ,
.Xr RSA_generate_key 3 ,
.Xr RSA_new 3 ,
.Xr RSA_print 3 ,
.Xr RSA_size 3
.Sh HISTORY
These functions first appeared in OpenSSL 1.1.0.