openssl/doc/man3/EVP_PKEY_CTX_new.pod
Richard Levitte f23bc0b770 EVP: Adapt KEYEXCH, SIGNATURE and ASYM_CIPHER to handle key types better
The adaptation is to handle the case when key types and operations
that use these keys have different names.  For example, EC keys can be
used for ECDSA and ECDH.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10647)
2020-01-09 15:01:28 +01:00

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=pod
=head1 NAME
EVP_PKEY_CTX_new, EVP_PKEY_CTX_new_id, EVP_PKEY_CTX_new_provided,
EVP_PKEY_CTX_dup, EVP_PKEY_CTX_free
- public key algorithm context functions
=head1 SYNOPSIS
#include <openssl/evp.h>
EVP_PKEY_CTX *EVP_PKEY_CTX_new(EVP_PKEY *pkey, ENGINE *e);
EVP_PKEY_CTX *EVP_PKEY_CTX_new_id(int id, ENGINE *e);
EVP_PKEY_CTX *EVP_PKEY_CTX_new_provided(OPENSSL_CTX *libctx,
const char *name,
const char *propquery);
EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *ctx);
void EVP_PKEY_CTX_free(EVP_PKEY_CTX *ctx);
=head1 DESCRIPTION
The EVP_PKEY_CTX_new() function allocates public key algorithm context using
the I<pkey> key type and ENGINE I<e>.
The EVP_PKEY_CTX_new_id() function allocates public key algorithm context
using the key type specified by I<id> and ENGINE I<e>.
The EVP_PKEY_CTX_new_provided() function allocates a public key algorithm
context using the library context I<libctx> (see L<OPENSSL_CTX(3)>), the
key type specified by I<name> and the property query I<propquery>. None
of the arguments are duplicated, so they must remain unchanged for the
lifetime of the returned B<EVP_PKEY_CTX> or of any of its duplicates.
EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_new_provided() are normally
used when no B<EVP_PKEY> structure is associated with the operations,
for example during parameter generation or key generation for some
algorithms.
EVP_PKEY_CTX_dup() duplicates the context I<ctx>.
EVP_PKEY_CTX_free() frees up the context I<ctx>.
If I<ctx> is NULL, nothing is done.
=head1 NOTES
=over 4
=item 1.
The B<EVP_PKEY_CTX> structure is an opaque public key algorithm context used
by the OpenSSL high level public key API. Contexts B<MUST NOT> be shared between
threads: that is it is not permissible to use the same context simultaneously
in two threads.
=item 2.
We mention "key type" in this manual, which is the same
as "algorithm" in most cases, allowing either term to be used
interchangeably. There are algorithms where the I<key type> and the
I<algorithm> of the operations that use the keys are not the same,
such as EC keys being used for ECDSA and ECDH operations.
=back
=head1 RETURN VALUES
EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id(), EVP_PKEY_CTX_dup() returns either
the newly allocated B<EVP_PKEY_CTX> structure of B<NULL> if an error occurred.
EVP_PKEY_CTX_free() does not return a value.
=head1 SEE ALSO
L<EVP_PKEY_new(3)>
=head1 HISTORY
These functions were added in OpenSSL 1.0.0.
=head1 COPYRIGHT
Copyright 2006-2016 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