doc/man3/EVP_PKEY_CTX_new.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 EVP_PKEY_CTX_new, EVP_PKEY_CTX_new_id, EVP_PKEY_CTX_new_from_name,
 EVP_PKEY_CTX_new_from_pkey, EVP_PKEY_CTX_dup, EVP_PKEY_CTX_free,
 EVP_PKEY_CTX_is_a
 - 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_from_name(OSSL_LIB_CTX *libctx,
                                           const char *name,
                                           const char *propquery);
  EVP_PKEY_CTX *EVP_PKEY_CTX_new_from_pkey(OSSL_LIB_CTX *libctx,
                                           EVP_PKEY *pkey,
                                           const char *propquery);
  EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *ctx);
  void EVP_PKEY_CTX_free(EVP_PKEY_CTX *ctx);
  int EVP_PKEY_CTX_is_a(EVP_PKEY_CTX *ctx, const char *keytype);

 =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_from_name() function allocates a public key algorithm
 context using the library context I<libctx> (see L<OSSL_LIB_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.  Read
 further about the possible names in L</NOTES> below.

 The EVP_PKEY_CTX_new_from_pkey() function allocates a public key algorithm
 context using the library context I<libctx> (see L<OSSL_LIB_CTX(3)>) and the
 algorithm specified by I<pkey> 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 any of its duplicates.

 EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_new_from_name() 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>. It is not supported for a
 keygen operation.

 EVP_PKEY_CTX_free() frees up the context I<ctx>.
 If I<ctx> is NULL, nothing is done.

 EVP_PKEY_is_a() checks if the key type associated with I<ctx> is I<keytype>.

 =head1 NOTES

 =head2 On B<EVP_PKEY_CTX>

 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.

 =head2 On Key Types

 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.

 Key types are given in two different manners:

 =over 4

 =item Legacy NID or EVP_PKEY type

 This is the I<id> used with EVP_PKEY_CTX_new_id().

 These are B<EVP_PKEY_RSA>, B<EVP_PKEY_RSA_PSS>, B<EVP_PKEY_DSA>,
 B<EVP_PKEY_DH>, B<EVP_PKEY_EC>, B<EVP_PKEY_SM2>, B<EVP_PKEY_X25519>,
 B<EVP_PKEY_X448>, and are used by legacy methods.

 =item Name strings

 This is the I<name> used with EVP_PKEY_CTX_new_from_name().

 These are names like "RSA", "DSA", and what's available depends on what
 providers are currently accessible.

 The OpenSSL providers offer a set of key types available this way, please
 see L<OSSL_PROVIDER-FIPS(7)> and L<OSSL_PROVIDER-default(7)> and related
 documentation for more information.

 =back

 =head1 RETURN VALUES

 EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_dup() return either
 the newly allocated B<EVP_PKEY_CTX> structure or B<NULL> if an error occurred.

 EVP_PKEY_CTX_free() does not return a value.

 EVP_PKEY_CTX_is_a() returns 1 for true and 0 for false.

 =head1 SEE ALSO

 L<EVP_PKEY_new(3)>

 =head1 HISTORY

 The EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id(), EVP_PKEY_CTX_dup() and
 EVP_PKEY_CTX_free() functions were added in OpenSSL 1.0.0.

 The EVP_PKEY_CTX_new_from_name() and EVP_PKEY_CTX_new_from_pkey() functions were
 added in OpenSSL 3.0.

 =head1 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
 L<https://www.openssl.org/source/license.html>.

 =cut
	=pod

	=head1 NAME

	EVP_PKEY_CTX_new, EVP_PKEY_CTX_new_id, EVP_PKEY_CTX_new_from_name,
	EVP_PKEY_CTX_new_from_pkey, EVP_PKEY_CTX_dup, EVP_PKEY_CTX_free,
	EVP_PKEY_CTX_is_a
	- 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_from_name(OSSL_LIB_CTX libctx,
	const char *name,
	const char *propquery);
	EVP_PKEY_CTX EVP_PKEY_CTX_new_from_pkey(OSSL_LIB_CTX libctx,
	EVP_PKEY *pkey,
	const char *propquery);
	EVP_PKEY_CTX EVP_PKEY_CTX_dup(const EVP_PKEY_CTX ctx);
	void EVP_PKEY_CTX_free(EVP_PKEY_CTX *ctx);
	int EVP_PKEY_CTX_is_a(EVP_PKEY_CTX ctx, const char keytype);

	=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_from_name() function allocates a public key algorithm
	context using the library context I<libctx> (see L<OSSL_LIB_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. Read
	further about the possible names in L</NOTES> below.

	The EVP_PKEY_CTX_new_from_pkey() function allocates a public key algorithm
	context using the library context I<libctx> (see L<OSSL_LIB_CTX(3)>) and the
	algorithm specified by I<pkey> 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 any of its duplicates.

	EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_new_from_name() 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>. It is not supported for a
	keygen operation.

	EVP_PKEY_CTX_free() frees up the context I<ctx>.
	If I<ctx> is NULL, nothing is done.

	EVP_PKEY_is_a() checks if the key type associated with I<ctx> is I<keytype>.

	=head1 NOTES

	=head2 On B<EVP_PKEY_CTX>

	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.

	=head2 On Key Types

	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.

	Key types are given in two different manners:

	=over 4

	=item Legacy NID or EVP_PKEY type

	This is the I<id> used with EVP_PKEY_CTX_new_id().

	These are B<EVP_PKEY_RSA>, B<EVP_PKEY_RSA_PSS>, B<EVP_PKEY_DSA>,
	B<EVP_PKEY_DH>, B<EVP_PKEY_EC>, B<EVP_PKEY_SM2>, B<EVP_PKEY_X25519>,
	B<EVP_PKEY_X448>, and are used by legacy methods.

	=item Name strings

	This is the I<name> used with EVP_PKEY_CTX_new_from_name().

	These are names like "RSA", "DSA", and what's available depends on what
	providers are currently accessible.

	The OpenSSL providers offer a set of key types available this way, please
	see L<OSSL_PROVIDER-FIPS(7)> and L<OSSL_PROVIDER-default(7)> and related
	documentation for more information.

	=back

	=head1 RETURN VALUES

	EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_dup() return either
	the newly allocated B<EVP_PKEY_CTX> structure or B<NULL> if an error occurred.

	EVP_PKEY_CTX_free() does not return a value.

	EVP_PKEY_CTX_is_a() returns 1 for true and 0 for false.

	=head1 SEE ALSO

	L<EVP_PKEY_new(3)>

	=head1 HISTORY

	The EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id(), EVP_PKEY_CTX_dup() and
	EVP_PKEY_CTX_free() functions were added in OpenSSL 1.0.0.

	The EVP_PKEY_CTX_new_from_name() and EVP_PKEY_CTX_new_from_pkey() functions were
	added in OpenSSL 3.0.

	=head1 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
	L<https://www.openssl.org/source/license.html>.

	=cut