=pod

=head1 NAME

EVP_PKEY_set1_RSA, EVP_PKEY_set1_DSA, EVP_PKEY_set1_DH, EVP_PKEY_set1_EC_KEY,
EVP_PKEY_get1_RSA, EVP_PKEY_get1_DSA, EVP_PKEY_get1_DH, EVP_PKEY_get1_EC_KEY,
EVP_PKEY_get0_RSA, EVP_PKEY_get0_DSA, EVP_PKEY_get0_DH, EVP_PKEY_get0_EC_KEY,
EVP_PKEY_assign_RSA, EVP_PKEY_assign_DSA, EVP_PKEY_assign_DH,
EVP_PKEY_assign_EC_KEY, EVP_PKEY_assign_POLY1305, EVP_PKEY_assign_SIPHASH,
EVP_PKEY_get0_hmac, EVP_PKEY_get0_poly1305, EVP_PKEY_get0_siphash,
EVP_PKEY_type, EVP_PKEY_id, EVP_PKEY_base_id, EVP_PKEY_set_alias_type,
EVP_PKEY_set1_engine, EVP_PKEY_get0_engine - EVP_PKEY assignment functions

=head1 SYNOPSIS

 #include <openssl/evp.h>

 int EVP_PKEY_set1_RSA(EVP_PKEY *pkey, RSA *key);
 int EVP_PKEY_set1_DSA(EVP_PKEY *pkey, DSA *key);
 int EVP_PKEY_set1_DH(EVP_PKEY *pkey, DH *key);
 int EVP_PKEY_set1_EC_KEY(EVP_PKEY *pkey, EC_KEY *key);

 RSA *EVP_PKEY_get1_RSA(EVP_PKEY *pkey);
 DSA *EVP_PKEY_get1_DSA(EVP_PKEY *pkey);
 DH *EVP_PKEY_get1_DH(EVP_PKEY *pkey);
 EC_KEY *EVP_PKEY_get1_EC_KEY(EVP_PKEY *pkey);

 const unsigned char *EVP_PKEY_get0_hmac(const EVP_PKEY *pkey, size_t *len);
 const unsigned char *EVP_PKEY_get0_poly1305(const EVP_PKEY *pkey, size_t *len);
 const unsigned char *EVP_PKEY_get0_siphash(const EVP_PKEY *pkey, size_t *len);
 RSA *EVP_PKEY_get0_RSA(EVP_PKEY *pkey);
 DSA *EVP_PKEY_get0_DSA(EVP_PKEY *pkey);
 DH *EVP_PKEY_get0_DH(EVP_PKEY *pkey);
 EC_KEY *EVP_PKEY_get0_EC_KEY(EVP_PKEY *pkey);

 int EVP_PKEY_assign_RSA(EVP_PKEY *pkey, RSA *key);
 int EVP_PKEY_assign_DSA(EVP_PKEY *pkey, DSA *key);
 int EVP_PKEY_assign_DH(EVP_PKEY *pkey, DH *key);
 int EVP_PKEY_assign_EC_KEY(EVP_PKEY *pkey, EC_KEY *key);
 int EVP_PKEY_assign_POLY1305(EVP_PKEY *pkey, ASN1_OCTET_STRING *key);
 int EVP_PKEY_assign_SIPHASH(EVP_PKEY *pkey, ASN1_OCTET_STRING *key);

 int EVP_PKEY_id(const EVP_PKEY *pkey);
 int EVP_PKEY_base_id(const EVP_PKEY *pkey);
 int EVP_PKEY_type(int type);
 int EVP_PKEY_set_alias_type(EVP_PKEY *pkey, int type);

 ENGINE *EVP_PKEY_get0_engine(const EVP_PKEY *pkey);
 int EVP_PKEY_set1_engine(EVP_PKEY *pkey, ENGINE *engine);

=head1 DESCRIPTION

EVP_PKEY_set1_RSA(), EVP_PKEY_set1_DSA(), EVP_PKEY_set1_DH() and
EVP_PKEY_set1_EC_KEY() set the key referenced by B<pkey> to B<key>.

EVP_PKEY_get1_RSA(), EVP_PKEY_get1_DSA(), EVP_PKEY_get1_DH() and
EVP_PKEY_get1_EC_KEY() return the referenced key in B<pkey> or
B<NULL> if the key is not of the correct type.

EVP_PKEY_get0_hmac(), EVP_PKEY_get0_poly1305(), EVP_PKEY_get0_siphash(),
EVP_PKEY_get0_RSA(), EVP_PKEY_get0_DSA(), EVP_PKEY_get0_DH()
and EVP_PKEY_get0_EC_KEY() also return the referenced key in B<pkey> or B<NULL>
if the key is not of the correct type but the reference count of the
returned key is B<not> incremented and so must not be freed up after use.

EVP_PKEY_assign_RSA(), EVP_PKEY_assign_DSA(), EVP_PKEY_assign_DH(),
EVP_PKEY_assign_EC_KEY(), EVP_PKEY_assign_POLY1305() and
EVP_PKEY_assign_SIPHASH() also set the referenced key to B<key>
however these use the supplied B<key> internally and so B<key>
will be freed when the parent B<pkey> is freed.

EVP_PKEY_base_id() returns the type of B<pkey>. For example
an RSA key will return B<EVP_PKEY_RSA>.

EVP_PKEY_id() returns the actual OID associated with B<pkey>. Historically keys
using the same algorithm could use different OIDs. For example an RSA key could
use the OIDs corresponding to the NIDs B<NID_rsaEncryption> (equivalent to
B<EVP_PKEY_RSA>) or B<NID_rsa> (equivalent to B<EVP_PKEY_RSA2>). The use of
alternative non-standard OIDs is now rare so B<EVP_PKEY_RSA2> et al are not
often seen in practice.

EVP_PKEY_type() returns the underlying type of the NID B<type>. For example
EVP_PKEY_type(EVP_PKEY_RSA2) will return B<EVP_PKEY_RSA>.

EVP_PKEY_get0_engine() returns a reference to the ENGINE handling B<pkey>.

EVP_PKEY_set1_engine() sets the ENGINE handling B<pkey> to B<engine>. It
must be called after the key algorithm and components are set up.
If B<engine> does not include an B<EVP_PKEY_METHOD> for B<pkey> an
error occurs.

EVP_PKEY_set_alias_type() allows modifying a EVP_PKEY to use a
different set of algorithms than the default. This is currently used
to support SM2 keys, which use an identical encoding to ECDSA.

=head1 NOTES

In accordance with the OpenSSL naming convention the key obtained
from or assigned to the B<pkey> using the B<1> functions must be
freed as well as B<pkey>.

EVP_PKEY_assign_RSA(), EVP_PKEY_assign_DSA(), EVP_PKEY_assign_DH(),
EVP_PKEY_assign_EC_KEY(), EVP_PKEY_assign_POLY1305()
and EVP_PKEY_assign_SIPHASH() are implemented as macros.

Most applications wishing to know a key type will simply call
EVP_PKEY_base_id() and will not care about the actual type:
which will be identical in almost all cases.

Previous versions of this document suggested using EVP_PKEY_type(pkey->type)
to determine the type of a key. Since B<EVP_PKEY> is now opaque this
is no longer possible: the equivalent is EVP_PKEY_base_id(pkey).

EVP_PKEY_set1_engine() is typically used by an ENGINE returning an HSM
key as part of its routine to load a private key.

=head1 RETURN VALUES

EVP_PKEY_set1_RSA(), EVP_PKEY_set1_DSA(), EVP_PKEY_set1_DH() and
EVP_PKEY_set1_EC_KEY() return 1 for success or 0 for failure.

EVP_PKEY_get1_RSA(), EVP_PKEY_get1_DSA(), EVP_PKEY_get1_DH() and
EVP_PKEY_get1_EC_KEY() return the referenced key or B<NULL> if
an error occurred.

EVP_PKEY_assign_RSA(), EVP_PKEY_assign_DSA(), EVP_PKEY_assign_DH(),
EVP_PKEY_assign_EC_KEY(), EVP_PKEY_assign_POLY1305()
and EVP_PKEY_assign_SIPHASH() return 1 for success and 0 for failure.

EVP_PKEY_base_id(), EVP_PKEY_id() and EVP_PKEY_type() return a key
type or B<NID_undef> (equivalently B<EVP_PKEY_NONE>) on error.

EVP_PKEY_set1_engine() returns 1 for success and 0 for failure.

EVP_PKEY_set_alias_type() returns 1 for success and 0 for error.

=head1 EXAMPLES

After loading an ECC key, it is possible to convert it to using SM2
algorithms with EVP_PKEY_set_alias_type:

 EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);

=head1 SEE ALSO

L<EVP_PKEY_new(3)>

=head1 COPYRIGHT

Copyright 2002-2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.

=cut