=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_get0, 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_id(const EVP_PKEY *pkey);
 int EVP_PKEY_base_id(const EVP_PKEY *pkey);
 int EVP_PKEY_type(int type);

Deprecated since OpenSSL 3.0, can be hidden entirely by defining
B<OPENSSL_API_COMPAT> with a suitable version value, see
L<openssl_user_macros(7)>:

 int EVP_PKEY_set_alias_type(EVP_PKEY *pkey, int type);

 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);
 const RSA *EVP_PKEY_get0_RSA(const EVP_PKEY *pkey);
 const DSA *EVP_PKEY_get0_DSA(const EVP_PKEY *pkey);
 const DH *EVP_PKEY_get0_DH(const EVP_PKEY *pkey);
 const EC_KEY *EVP_PKEY_get0_EC_KEY(const EVP_PKEY *pkey);
 void *EVP_PKEY_get0(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);

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

=head1 DESCRIPTION

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

EVP_PKEY_id() returns the actual OID associated with I<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 I<type>. For example
EVP_PKEY_type(EVP_PKEY_RSA2) will return B<EVP_PKEY_RSA>.

EVP_PKEY_set1_RSA(), EVP_PKEY_set1_DSA(), EVP_PKEY_set1_DH() and
EVP_PKEY_set1_EC_KEY() set the key referenced by I<pkey> to I<key>. These
functions are deprecated. Applications should instead use
L<EVP_PKEY_fromdata(3)>.

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() set the referenced key to I<key> however these use
the supplied I<key> internally and so I<key> will be freed when the parent
I<pkey> is freed. These macros are deprecated. Applications should instead read
an EVP_PKEY directly using the OSSL_DECODER APIs (see
L<OSSL_DECODER_CTX_new_for_pkey(3)>), or construct an EVP_PKEY from data using
L<EVP_PKEY_fromdata(3)>.

EVP_PKEY_get1_RSA(), EVP_PKEY_get1_DSA(), EVP_PKEY_get1_DH() and
EVP_PKEY_get1_EC_KEY() return the referenced key in I<pkey> or NULL if the
key is not of the correct type. The returned key must be freed after use.
These functions are deprecated. Applications should instead use the EVP_PKEY
directly where possible. If access to the low level key parameters is required
then applications should use L<EVP_PKEY_get_params(3)> and other similar
functions. To write an EVP_PKEY out use the OSSL_ENCODER APIs (see
L<OSSL_ENCODER_CTX_new_for_pkey(3)>).

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() return the referenced key in I<pkey> or NULL if the
key is not of the correct type. The reference count of the returned key is
B<not> incremented and so the key must not be freed after use. These functions
are deprecated. Applications should instead use the EVP_PKEY directly where
possible. If access to the low level key parameters is required then
applications should use L<EVP_PKEY_get_params(3)> and other similar functions.
To write an EVP_PKEY out use the OSSL_ENCODER APIs (see
L<OSSL_ENCODER_CTX_new_for_pkey(3)>). EVP_PKEY_get0() returns a pointer to the
legacy key or NULL if the key is not legacy.

Note that if an EVP_PKEY was not constructed using one of the deprecated
functions such as EVP_PKEY_set1_RSA(), EVP_PKEY_set1_DSA(), EVP_PKEY_set1_DH()
or EVP_PKEY_set1_EC_KEY(), or via the similarly named B<EVP_PKEY_assign> macros
described above then the internal key will be managed by a provider (see
L<provider(7)>). In that case the key returned by EVP_PKEY_get1_RSA(),
EVP_PKEY_get1_DSA(), EVP_PKEY_get1_DH(), EVP_PKEY_get1_EC_KEY(),
EVP_PKEY_get0_hmac(), EVP_PKEY_get0_poly1305(), EVP_PKEY_get0_siphash(),
EVP_PKEY_get0_RSA(), EVP_PKEY_get0_DSA(), EVP_PKEY_get0_DH() or
EVP_PKEY_get0_EC_KEY() will be a cached copy of the provider's key. Subsequent
updates to the provider's key will not be reflected back in the cached copy, and
updates made by an application to the returned key will not be reflected back in
the provider's key. Subsequent calls to EVP_PKEY_get1_RSA(),
EVP_PKEY_get1_DSA(), EVP_PKEY_get1_DH() and EVP_PKEY_get1_EC_KEY() will always
return the cached copy returned by the first call.

EVP_PKEY_get0_engine() returns a reference to the ENGINE handling I<pkey>. This
function is deprecated. Applications should use providers instead of engines
(see L<provider(7)> for details).

EVP_PKEY_set1_engine() sets the ENGINE handling I<pkey> to I<engine>. It
must be called after the key algorithm and components are set up.
If I<engine> does not include an B<EVP_PKEY_METHOD> for I<pkey> an
error occurs. This function is deprecated. Applications should use providers
instead of engines (see L<provider(7)> for details).

EVP_PKEY_set_alias_type() allows modifying an EVP_PKEY to use a
different set of algorithms than the default. This function is deprecated and
was previously needed as a workaround to recognise SM2 keys. From OpenSSL 3.0,
this key type is internally recognised so the workaround is no longer needed.
Functionality is still retained as it is, but will only work with EVP_PKEYs
with a legacy internal key.

=head1 WARNINGS

The following functions are only reliable with B<EVP_PKEY>s that have
been assigned an internal key with EVP_PKEY_assign_*():

EVP_PKEY_id(), EVP_PKEY_base_id(), EVP_PKEY_type(), EVP_PKEY_set_alias_type()

For EVP_PKEY key type checking purposes, L<EVP_PKEY_is_a(3)> is more generic.

The keys returned from the functions EVP_PKEY_get0_RSA(), EVP_PKEY_get0_DSA(),
EVP_PKEY_get0_DH() and EVP_PKEY_get0_EC_KEY() were changed to have a "const"
return type in OpenSSL 3.0. As described above the keys returned may be cached
copies of the key held in a provider. Due to this, and unlike in earlier
versions of OpenSSL, they should be considered read-only copies of the key.
Updates to these keys will not be reflected back in the provider side key. The
EVP_PKEY_get1_RSA(), EVP_PKEY_get1_DSA(), EVP_PKEY_get1_DH() and
EVP_PKEY_get1_EC_KEY() functions were not changed to have a "const" return type
in order that applications can "free" the return value. However applications
should still consider them as read-only copies.

=head1 NOTES

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

EVP_PKEY_assign_EC_KEY() looks at the curve name id to determine if
the passed B<EC_KEY> is an L<SM2(7)> key, and will set the B<EVP_PKEY>
type to B<EVP_PKEY_SM2> in that case, instead of B<EVP_PKEY_EC>.

It's possible to switch back and forth between the types B<EVP_PKEY_EC>
and B<EVP_PKEY_SM2> with a call to EVP_PKEY_set_alias_type() on keys
assigned with this macro if it's desirable to do a normal EC
computations with the SM2 curve instead of the special SM2
computations, and vice versa.

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 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)>, L<SM2(7)>

=head1 HISTORY

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_set_alias_type, EVP_PKEY_set1_engine and EVP_PKEY_get0_engine were
deprecated in OpenSSL 3.0.

The return value from EVP_PKEY_get0_RSA, EVP_PKEY_get0_DSA, EVP_PKEY_get0_DH,
EVP_PKEY_get0_EC_KEY were made const in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2002-2021 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