doc/man7/provider-asym_cipher.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 provider-asym_cipher - The asym_cipher library E<lt>-E<gt> provider functions

 =head1 SYNOPSIS

 =for openssl multiple includes

  #include <openssl/core_dispatch.h>
  #include <openssl/core_names.h>

  /*
   * None of these are actual functions, but are displayed like this for
   * the function signatures for functions that are offered as function
   * pointers in OSSL_DISPATCH arrays.
   */

  /* Context management */
  void *OSSL_FUNC_asym_cipher_newctx(void *provctx);
  void OSSL_FUNC_asym_cipher_freectx(void *ctx);
  void *OSSL_FUNC_asym_cipher_dupctx(void *ctx);

  /* Encryption */
  int OSSL_FUNC_asym_cipher_encrypt_init(void *ctx, void *provkey,
                                         const OSSL_PARAM params[]);
  int OSSL_FUNC_asym_cipher_encrypt(void *ctx, unsigned char *out, size_t *outlen,
                                    size_t outsize, const unsigned char *in,
                                    size_t inlen);

  /* Decryption */
  int OSSL_FUNC_asym_cipher_decrypt_init(void *ctx, void *provkey,
                                         const OSSL_PARAM params[]);
  int OSSL_FUNC_asym_cipher_decrypt(void *ctx, unsigned char *out, size_t *outlen,
                                    size_t outsize, const unsigned char *in,
                                    size_t inlen);

  /* Asymmetric Cipher parameters */
  int OSSL_FUNC_asym_cipher_get_ctx_params(void *ctx, OSSL_PARAM params[]);
  const OSSL_PARAM *OSSL_FUNC_asym_cipher_gettable_ctx_params(void *provctx);
  int OSSL_FUNC_asym_cipher_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
  const OSSL_PARAM *OSSL_FUNC_asym_cipher_settable_ctx_params(void *provctx);

 =head1 DESCRIPTION

 This documentation is primarily aimed at provider authors. See L<provider(7)>
 for further information.

 The asymmetric cipher (OSSL_OP_ASYM_CIPHER) operation enables providers to
 implement asymmetric cipher algorithms and make them available to applications
 via the API functions L<EVP_PKEY_encrypt(3)>,
 L<EVP_PKEY_decrypt(3)> and
 other related functions).

 All "functions" mentioned here are passed as function pointers between
 F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via
 B<OSSL_ALGORITHM> arrays that are returned by the provider's
 provider_query_operation() function
 (see L<provider-base(7)/Provider Functions>).

 All these "functions" have a corresponding function type definition
 named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
 function pointer from an B<OSSL_DISPATCH> element named
 B<OSSL_FUNC_{name}>.
 For example, the "function" OSSL_FUNC_asym_cipher_newctx() has these:

  typedef void *(OSSL_FUNC_asym_cipher_newctx_fn)(void *provctx);
  static ossl_inline OSSL_FUNC_asym_cipher_newctx_fn
      OSSL_FUNC_asym_cipher_newctx(const OSSL_DISPATCH *opf);

 B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as
 macros in L<openssl-core_dispatch.h(7)>, as follows:

  OSSL_FUNC_asym_cipher_newctx               OSSL_FUNC_ASYM_CIPHER_NEWCTX
  OSSL_FUNC_asym_cipher_freectx              OSSL_FUNC_ASYM_CIPHER_FREECTX
  OSSL_FUNC_asym_cipher_dupctx               OSSL_FUNC_ASYM_CIPHER_DUPCTX

  OSSL_FUNC_asym_cipher_encrypt_init         OSSL_FUNC_ASYM_CIPHER_ENCRYPT_INIT
  OSSL_FUNC_asym_cipher_encrypt              OSSL_FUNC_ASYM_CIPHER_ENCRYPT

  OSSL_FUNC_asym_cipher_decrypt_init         OSSL_FUNC_ASYM_CIPHER_DECRYPT_INIT
  OSSL_FUNC_asym_cipher_decrypt              OSSL_FUNC_ASYM_CIPHER_DECRYPT

  OSSL_FUNC_asym_cipher_get_ctx_params       OSSL_FUNC_ASYM_CIPHER_GET_CTX_PARAMS
  OSSL_FUNC_asym_cipher_gettable_ctx_params  OSSL_FUNC_ASYM_CIPHER_GETTABLE_CTX_PARAMS
  OSSL_FUNC_asym_cipher_set_ctx_params       OSSL_FUNC_ASYM_CIPHER_SET_CTX_PARAMS
  OSSL_FUNC_asym_cipher_settable_ctx_params  OSSL_FUNC_ASYM_CIPHER_SETTABLE_CTX_PARAMS

 An asymmetric cipher algorithm implementation may not implement all of these
 functions.
 In order to be a consistent set of functions a provider must implement
 OSSL_FUNC_asym_cipher_newctx and OSSL_FUNC_asym_cipher_freectx.
 It must also implement both of OSSL_FUNC_asym_cipher_encrypt_init and
 OSSL_FUNC_asym_cipher_encrypt, or both of OSSL_FUNC_asym_cipher_decrypt_init and
 OSSL_FUNC_asym_cipher_decrypt.
 OSSL_FUNC_asym_cipher_get_ctx_params is optional but if it is present then so must
 OSSL_FUNC_asym_cipher_gettable_ctx_params.
 Similarly, OSSL_FUNC_asym_cipher_set_ctx_params is optional but if it is present then
 so must OSSL_FUNC_asym_cipher_settable_ctx_params.

 An asymmetric cipher algorithm must also implement some mechanism for generating,
 loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation.
 See L<provider-keymgmt(7)> for further details.

 =head2 Context Management Functions

 OSSL_FUNC_asym_cipher_newctx() should create and return a pointer to a provider side
 structure for holding context information during an asymmetric cipher operation.
 A pointer to this context will be passed back in a number of the other
 asymmetric cipher operation function calls.
 The parameter I<provctx> is the provider context generated during provider
 initialisation (see L<provider(7)>).

 OSSL_FUNC_asym_cipher_freectx() is passed a pointer to the provider side asymmetric
 cipher context in the I<ctx> parameter.
 This function should free any resources associated with that context.

 OSSL_FUNC_asym_cipher_dupctx() should duplicate the provider side asymmetric cipher
 context in the I<ctx> parameter and return the duplicate copy.

 =head2 Encryption Functions

 OSSL_FUNC_asym_cipher_encrypt_init() initialises a context for an asymmetric encryption
 given a provider side asymmetric cipher context in the I<ctx> parameter, and a
 pointer to a provider key object in the I<provkey> parameter.
 The I<params>, if not NULL, should be set on the context in a manner similar to
 using OSSL_FUNC_asym_cipher_set_ctx_params().
 The key object should have been previously generated, loaded or imported into
 the provider using the key management (OSSL_OP_KEYMGMT) operation (see
 provider-keymgmt(7)>.
 OSSL_FUNC_asym_cipher_encrypt() performs the actual encryption itself.
 A previously initialised asymmetric cipher context is passed in the I<ctx>
 parameter.
 The data to be encrypted is pointed to by the I<in> parameter which is I<inlen>
 bytes long.
 Unless I<out> is NULL, the encrypted data should be written to the location
 pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in
 length.
 The length of the encrypted data should be written to I<*outlen>.
 If I<out> is NULL then the maximum length of the encrypted data should be
 written to I<*outlen>.

 =head2 Decryption Functions

 OSSL_FUNC_asym_cipher_decrypt_init() initialises a context for an asymmetric decryption
 given a provider side asymmetric cipher context in the I<ctx> parameter, and a
 pointer to a provider key object in the I<provkey> parameter.
 The I<params>, if not NULL, should be set on the context in a manner similar to
 using OSSL_FUNC_asym_cipher_set_ctx_params().
 The key object should have been previously generated, loaded or imported into
 the provider using the key management (OSSL_OP_KEYMGMT) operation (see
 provider-keymgmt(7)>.

 OSSL_FUNC_asym_cipher_decrypt() performs the actual decryption itself.
 A previously initialised asymmetric cipher context is passed in the I<ctx>
 parameter.
 The data to be decrypted is pointed to by the I<in> parameter which is I<inlen>
 bytes long.
 Unless I<out> is NULL, the decrypted data should be written to the location
 pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in
 length.
 The length of the decrypted data should be written to I<*outlen>.
 If I<out> is NULL then the maximum length of the decrypted data should be
 written to I<*outlen>.

 =head2 Asymmetric Cipher Parameters

 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
 the OSSL_FUNC_asym_cipher_get_ctx_params() and OSSL_FUNC_asym_cipher_set_ctx_params()
 functions.

 OSSL_FUNC_asym_cipher_get_ctx_params() gets asymmetric cipher parameters associated
 with the given provider side asymmetric cipher context I<ctx> and stores them in
 I<params>.
 Passing NULL for I<params> should return true.

 OSSL_FUNC_asym_cipher_set_ctx_params() sets the asymmetric cipher parameters associated
 with the given provider side asymmetric cipher context I<ctx> to I<params>.
 Any parameter settings are additional to any that were previously set.
 Passing NULL for I<params> should return true.

 Parameters currently recognised by built-in asymmetric cipher algorithms are as
 follows.
 Not all parameters are relevant to, or are understood by all asymmetric cipher
 algorithms:

 =over 4

 =item "pad-mode" (B<OSSL_ASYM_CIPHER_PARAM_PAD_MODE>) <integer>

 The type of padding to be used. The interpretation of this value will depend
 on the algorithm in use. The default provider understands these RSA padding
 modes: 1 (RSA_PKCS1_PADDING), 3 (RSA_NO_PADDING),
 4 (RSA_PKCS1_OAEP_PADDING), 5 (RSA_X931_PADDING), 6 (RSA_PKCS1_PSS_PADDING) and
 7 (RSA_PKCS1_WITH_TLS_PADDING). See L<EVP_PKEY_CTX_set_rsa_padding(3)> for
 further details.

 =item "digest" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST>) <UTF8 string>

 Gets or sets the name of the OAEP digest algorithm used when OAEP padding is in
 use.

 =item "digest" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST>) <UTF8 string>

 Gets or sets the name of the digest algorithm used by the algorithm (where
 applicable).

 =item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST_PROPS>) <UTF8 string>

 Gets or sets the properties to use when fetching the OAEP digest algorithm.

 =item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST_PROPS>) <UTF8 string>

 Gets or sets the properties to use when fetching the cipher digest algorithm.

 =item "mgf1-digest" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST>) <UTF8 string>

 Gets or sets the name of the MGF1 digest algorithm used when OAEP or PSS padding
 is in use.

 =item "mgf1-digest-props" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS>) <UTF8 string>

 Gets or sets the properties to use when fetching the MGF1 digest algorithm.

 =item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string>

 Gets or sets the OAEP label used when OAEP padding is in use.

 =item "tls-client-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer>

 The TLS protocol version first requested by the client. See
 B<RSA_PKCS1_WITH_TLS_PADDING> on the page L<EVP_PKEY_CTX_set_rsa_padding(3)>.

 =item "tls-negotiated-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer>

 The negotiated TLS protocol version. See
 B<RSA_PKCS1_WITH_TLS_PADDING> on the page L<EVP_PKEY_CTX_set_rsa_padding(3)>.

 =back

 OSSL_FUNC_asym_cipher_gettable_ctx_params() and OSSL_FUNC_asym_cipher_settable_ctx_params()
 get a constant B<OSSL_PARAM> array that describes the gettable and settable
 parameters, i.e. parameters that can be used with OSSL_FUNC_asym_cipherget_ctx_params()
 and OSSL_FUNC_asym_cipher_set_ctx_params() respectively.
 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.

 =head1 RETURN VALUES

 OSSL_FUNC_asym_cipher_newctx() and OSSL_FUNC_asym_cipher_dupctx() should return the newly
 created provider side asymmetric cipher context, or NULL on failure.

 All other functions should return 1 for success or 0 on error.

 =head1 SEE ALSO

 L<provider(7)>

 =head1 HISTORY

 The provider ASYM_CIPHER interface was introduced in OpenSSL 3.0.

 =head1 COPYRIGHT

 Copyright 2019-2021 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

	provider-asym_cipher - The asym_cipher library E<lt>-E<gt> provider functions

	=head1 SYNOPSIS

	=for openssl multiple includes

	#include <openssl/core_dispatch.h>
	#include <openssl/core_names.h>

	/*
	* None of these are actual functions, but are displayed like this for
	* the function signatures for functions that are offered as function
	* pointers in OSSL_DISPATCH arrays.
	*/

	/* Context management */
	void OSSL_FUNC_asym_cipher_newctx(void provctx);
	void OSSL_FUNC_asym_cipher_freectx(void *ctx);
	void OSSL_FUNC_asym_cipher_dupctx(void ctx);

	/* Encryption */
	int OSSL_FUNC_asym_cipher_encrypt_init(void ctx, void provkey,
	const OSSL_PARAM params[]);
	int OSSL_FUNC_asym_cipher_encrypt(void ctx, unsigned char out, size_t *outlen,
	size_t outsize, const unsigned char *in,
	size_t inlen);

	/* Decryption */
	int OSSL_FUNC_asym_cipher_decrypt_init(void ctx, void provkey,
	const OSSL_PARAM params[]);
	int OSSL_FUNC_asym_cipher_decrypt(void ctx, unsigned char out, size_t *outlen,
	size_t outsize, const unsigned char *in,
	size_t inlen);

	/* Asymmetric Cipher parameters */
	int OSSL_FUNC_asym_cipher_get_ctx_params(void *ctx, OSSL_PARAM params[]);
	const OSSL_PARAM OSSL_FUNC_asym_cipher_gettable_ctx_params(void provctx);
	int OSSL_FUNC_asym_cipher_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
	const OSSL_PARAM OSSL_FUNC_asym_cipher_settable_ctx_params(void provctx);

	=head1 DESCRIPTION

	This documentation is primarily aimed at provider authors. See L<provider(7)>
	for further information.

	The asymmetric cipher (OSSL_OP_ASYM_CIPHER) operation enables providers to
	implement asymmetric cipher algorithms and make them available to applications
	via the API functions L<EVP_PKEY_encrypt(3)>,
	L<EVP_PKEY_decrypt(3)> and
	other related functions).

	All "functions" mentioned here are passed as function pointers between
	F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via
	B<OSSL_ALGORITHM> arrays that are returned by the provider's
	provider_query_operation() function
	(see L<provider-base(7)/Provider Functions>).

	All these "functions" have a corresponding function type definition
	named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
	function pointer from an B<OSSL_DISPATCH> element named
	B<OSSL_FUNC_{name}>.
	For example, the "function" OSSL_FUNC_asym_cipher_newctx() has these:

	typedef void (OSSL_FUNC_asym_cipher_newctx_fn)(void provctx);
	static ossl_inline OSSL_FUNC_asym_cipher_newctx_fn
	OSSL_FUNC_asym_cipher_newctx(const OSSL_DISPATCH *opf);

	B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as
	macros in L<openssl-core_dispatch.h(7)>, as follows:

	OSSL_FUNC_asym_cipher_newctx OSSL_FUNC_ASYM_CIPHER_NEWCTX
	OSSL_FUNC_asym_cipher_freectx OSSL_FUNC_ASYM_CIPHER_FREECTX
	OSSL_FUNC_asym_cipher_dupctx OSSL_FUNC_ASYM_CIPHER_DUPCTX

	OSSL_FUNC_asym_cipher_encrypt_init OSSL_FUNC_ASYM_CIPHER_ENCRYPT_INIT
	OSSL_FUNC_asym_cipher_encrypt OSSL_FUNC_ASYM_CIPHER_ENCRYPT

	OSSL_FUNC_asym_cipher_decrypt_init OSSL_FUNC_ASYM_CIPHER_DECRYPT_INIT
	OSSL_FUNC_asym_cipher_decrypt OSSL_FUNC_ASYM_CIPHER_DECRYPT

	OSSL_FUNC_asym_cipher_get_ctx_params OSSL_FUNC_ASYM_CIPHER_GET_CTX_PARAMS
	OSSL_FUNC_asym_cipher_gettable_ctx_params OSSL_FUNC_ASYM_CIPHER_GETTABLE_CTX_PARAMS
	OSSL_FUNC_asym_cipher_set_ctx_params OSSL_FUNC_ASYM_CIPHER_SET_CTX_PARAMS
	OSSL_FUNC_asym_cipher_settable_ctx_params OSSL_FUNC_ASYM_CIPHER_SETTABLE_CTX_PARAMS

	An asymmetric cipher algorithm implementation may not implement all of these
	functions.
	In order to be a consistent set of functions a provider must implement
	OSSL_FUNC_asym_cipher_newctx and OSSL_FUNC_asym_cipher_freectx.
	It must also implement both of OSSL_FUNC_asym_cipher_encrypt_init and
	OSSL_FUNC_asym_cipher_encrypt, or both of OSSL_FUNC_asym_cipher_decrypt_init and
	OSSL_FUNC_asym_cipher_decrypt.
	OSSL_FUNC_asym_cipher_get_ctx_params is optional but if it is present then so must
	OSSL_FUNC_asym_cipher_gettable_ctx_params.
	Similarly, OSSL_FUNC_asym_cipher_set_ctx_params is optional but if it is present then
	so must OSSL_FUNC_asym_cipher_settable_ctx_params.

	An asymmetric cipher algorithm must also implement some mechanism for generating,
	loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation.
	See L<provider-keymgmt(7)> for further details.

	=head2 Context Management Functions

	OSSL_FUNC_asym_cipher_newctx() should create and return a pointer to a provider side
	structure for holding context information during an asymmetric cipher operation.
	A pointer to this context will be passed back in a number of the other
	asymmetric cipher operation function calls.
	The parameter I<provctx> is the provider context generated during provider
	initialisation (see L<provider(7)>).

	OSSL_FUNC_asym_cipher_freectx() is passed a pointer to the provider side asymmetric
	cipher context in the I<ctx> parameter.
	This function should free any resources associated with that context.

	OSSL_FUNC_asym_cipher_dupctx() should duplicate the provider side asymmetric cipher
	context in the I<ctx> parameter and return the duplicate copy.

	=head2 Encryption Functions

	OSSL_FUNC_asym_cipher_encrypt_init() initialises a context for an asymmetric encryption
	given a provider side asymmetric cipher context in the I<ctx> parameter, and a
	pointer to a provider key object in the I<provkey> parameter.
	The I<params>, if not NULL, should be set on the context in a manner similar to
	using OSSL_FUNC_asym_cipher_set_ctx_params().
	The key object should have been previously generated, loaded or imported into
	the provider using the key management (OSSL_OP_KEYMGMT) operation (see
	provider-keymgmt(7)>.
	OSSL_FUNC_asym_cipher_encrypt() performs the actual encryption itself.
	A previously initialised asymmetric cipher context is passed in the I<ctx>
	parameter.
	The data to be encrypted is pointed to by the I<in> parameter which is I<inlen>
	bytes long.
	Unless I<out> is NULL, the encrypted data should be written to the location
	pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in
	length.
	The length of the encrypted data should be written to I<*outlen>.
	If I<out> is NULL then the maximum length of the encrypted data should be
	written to I<*outlen>.

	=head2 Decryption Functions

	OSSL_FUNC_asym_cipher_decrypt_init() initialises a context for an asymmetric decryption
	given a provider side asymmetric cipher context in the I<ctx> parameter, and a
	pointer to a provider key object in the I<provkey> parameter.
	The I<params>, if not NULL, should be set on the context in a manner similar to
	using OSSL_FUNC_asym_cipher_set_ctx_params().
	The key object should have been previously generated, loaded or imported into
	the provider using the key management (OSSL_OP_KEYMGMT) operation (see
	provider-keymgmt(7)>.

	OSSL_FUNC_asym_cipher_decrypt() performs the actual decryption itself.
	A previously initialised asymmetric cipher context is passed in the I<ctx>
	parameter.
	The data to be decrypted is pointed to by the I<in> parameter which is I<inlen>
	bytes long.
	Unless I<out> is NULL, the decrypted data should be written to the location
	pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in
	length.
	The length of the decrypted data should be written to I<*outlen>.
	If I<out> is NULL then the maximum length of the decrypted data should be
	written to I<*outlen>.

	=head2 Asymmetric Cipher Parameters

	See L<OSSL_PARAM(3)> for further details on the parameters structure used by
	the OSSL_FUNC_asym_cipher_get_ctx_params() and OSSL_FUNC_asym_cipher_set_ctx_params()
	functions.

	OSSL_FUNC_asym_cipher_get_ctx_params() gets asymmetric cipher parameters associated
	with the given provider side asymmetric cipher context I<ctx> and stores them in
	I<params>.
	Passing NULL for I<params> should return true.

	OSSL_FUNC_asym_cipher_set_ctx_params() sets the asymmetric cipher parameters associated
	with the given provider side asymmetric cipher context I<ctx> to I<params>.
	Any parameter settings are additional to any that were previously set.
	Passing NULL for I<params> should return true.

	Parameters currently recognised by built-in asymmetric cipher algorithms are as
	follows.
	Not all parameters are relevant to, or are understood by all asymmetric cipher
	algorithms:

	=over 4

	=item "pad-mode" (B<OSSL_ASYM_CIPHER_PARAM_PAD_MODE>) <integer>

	The type of padding to be used. The interpretation of this value will depend
	on the algorithm in use. The default provider understands these RSA padding
	modes: 1 (RSA_PKCS1_PADDING), 3 (RSA_NO_PADDING),
	4 (RSA_PKCS1_OAEP_PADDING), 5 (RSA_X931_PADDING), 6 (RSA_PKCS1_PSS_PADDING) and
	7 (RSA_PKCS1_WITH_TLS_PADDING). See L<EVP_PKEY_CTX_set_rsa_padding(3)> for
	further details.

	=item "digest" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST>) <UTF8 string>

	Gets or sets the name of the OAEP digest algorithm used when OAEP padding is in
	use.

	=item "digest" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST>) <UTF8 string>

	Gets or sets the name of the digest algorithm used by the algorithm (where
	applicable).

	=item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST_PROPS>) <UTF8 string>

	Gets or sets the properties to use when fetching the OAEP digest algorithm.

	=item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST_PROPS>) <UTF8 string>

	Gets or sets the properties to use when fetching the cipher digest algorithm.

	=item "mgf1-digest" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST>) <UTF8 string>

	Gets or sets the name of the MGF1 digest algorithm used when OAEP or PSS padding
	is in use.

	=item "mgf1-digest-props" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS>) <UTF8 string>

	Gets or sets the properties to use when fetching the MGF1 digest algorithm.

	=item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string>

	Gets or sets the OAEP label used when OAEP padding is in use.

	=item "tls-client-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer>

	The TLS protocol version first requested by the client. See
	B<RSA_PKCS1_WITH_TLS_PADDING> on the page L<EVP_PKEY_CTX_set_rsa_padding(3)>.

	=item "tls-negotiated-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer>

	The negotiated TLS protocol version. See
	B<RSA_PKCS1_WITH_TLS_PADDING> on the page L<EVP_PKEY_CTX_set_rsa_padding(3)>.

	=back

	OSSL_FUNC_asym_cipher_gettable_ctx_params() and OSSL_FUNC_asym_cipher_settable_ctx_params()
	get a constant B<OSSL_PARAM> array that describes the gettable and settable
	parameters, i.e. parameters that can be used with OSSL_FUNC_asym_cipherget_ctx_params()
	and OSSL_FUNC_asym_cipher_set_ctx_params() respectively.
	See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.

	=head1 RETURN VALUES

	OSSL_FUNC_asym_cipher_newctx() and OSSL_FUNC_asym_cipher_dupctx() should return the newly
	created provider side asymmetric cipher context, or NULL on failure.

	All other functions should return 1 for success or 0 on error.

	=head1 SEE ALSO

	L<provider(7)>

	=head1 HISTORY

	The provider ASYM_CIPHER interface was introduced in OpenSSL 3.0.

	=head1 COPYRIGHT

	Copyright 2019-2021 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