=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(const EVP_PKEY *pkey);
 DSA *EVP_PKEY_get0_DSA(const EVP_PKEY *pkey);
 DH *EVP_PKEY_get0_DH(const EVP_PKEY *pkey);
 EC_KEY *EVP_PKEY_get0_EC_KEY(const 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 2002-2018 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (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
