EVP_PKEY_COPY_PARAMETERS(3ssl) | OpenSSL | EVP_PKEY_COPY_PARAMETERS(3ssl) |

# NAME

EVP_PKEY_missing_parameters, EVP_PKEY_copy_parameters, EVP_PKEY_parameters_eq, EVP_PKEY_cmp_parameters, EVP_PKEY_eq, EVP_PKEY_cmp - public key parameter and comparison functions

# SYNOPSIS

#include <openssl/evp.h> int EVP_PKEY_missing_parameters(const EVP_PKEY *pkey); int EVP_PKEY_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from); int EVP_PKEY_parameters_eq(const EVP_PKEY *a, const EVP_PKEY *b); int EVP_PKEY_eq(const EVP_PKEY *a, const EVP_PKEY *b);

The following functions have been deprecated since OpenSSL 3.0,
and can be hidden entirely by defining **OPENSSL_API_COMPAT** with a
suitable version value, see openssl_user_macros(7):

int EVP_PKEY_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b); int EVP_PKEY_cmp(const EVP_PKEY *a, const EVP_PKEY *b);

# DESCRIPTION

The function **EVP_PKEY_missing_parameters()** returns 1 if the
public key parameters of **pkey** are missing and 0 if they are present
or the algorithm doesn't use parameters.

The function **EVP_PKEY_copy_parameters()** copies the
parameters from key **from** to key **to**. An error is returned if
the parameters are missing in **from** or present in both **from** and
**to** and mismatch. If the parameters in **from** and **to** are
both present and match this function has no effect.

The function **EVP_PKEY_parameters_eq()** checks the parameters
of keys **a** and **b** for equality.

The function **EVP_PKEY_eq()** checks the keys **a** and
**b** for equality, including their parameters if they are available.

# NOTES

The main purpose of the functions
**EVP_PKEY_missing_parameters()** and **EVP_PKEY_copy_parameters()**
is to handle public keys in certificates where the parameters are sometimes
omitted from a public key if they are inherited from the CA that signed
it.

The deprecated functions **EVP_PKEY_cmp()** and
**EVP_PKEY_cmp_parameters()** differ in their return values compared to
other **_cmp()** functions. They are aliases for **EVP_PKEY_eq()** and
**EVP_PKEY_parameters_eq()**.

The function **EVP_PKEY_cmp()** previously only checked the key
parameters (if there are any) and the public key, assuming that there always
was a public key and that private key equality could be derived from that.
Because it's no longer assumed that the private key in an EVP_PKEY(3)
is always accompanied by a public key, the comparison can not rely on public
key comparison alone.

Instead, **EVP_PKEY_eq()** (and therefore also
**EVP_PKEY_cmp()**) now compares:

- 1.
- the key parameters (if there are any)
- 2.
- the public keys or the private keys of the two
**EVP_PKEY**s, depending on what they both contain.

# RETURN VALUES

The function **EVP_PKEY_missing_parameters()** returns 1 if the
public key parameters of **pkey** are missing and 0 if they are present
or the algorithm doesn't use parameters.

These functions **EVP_PKEY_copy_parameters()** returns 1 for
success and 0 for failure.

The functions **EVP_PKEY_cmp_parameters()**,
**EVP_PKEY_parameters_eq()**, **EVP_PKEY_cmp()** and
**EVP_PKEY_eq()** return 1 if their inputs match, 0 if they don't match,
-1 if the key types are different and -2 if the operation is not
supported.

# SEE ALSO

# HISTORY

The **EVP_PKEY_cmp()** and **EVP_PKEY_cmp_parameters()**
functions were deprecated in OpenSSL 3.0.

The **EVP_PKEY_eq()** and **EVP_PKEY_parameters_eq()** were
added in OpenSSL 3.0 to replace **EVP_PKEY_cmp()** and
**EVP_PKEY_cmp_parameters()**.

# COPYRIGHT

Copyright 2006-2021 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 https://www.openssl.org/source/license.html.

2023-10-24 | 3.1.4 |