--- /dev/null
+=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_numbers.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 *OP_asym_cipher_newctx(void *provctx);
+ void OP_asym_cipher_freectx(void *ctx);
+ void *OP_asym_cipher_dupctx(void *ctx);
+
+ /* Encryption */
+ int OP_asym_cipher_encrypt_init(void *ctx, void *provkey);
+ int OP_asym_cipher_encrypt(void *ctx, unsigned char *out, size_t *outlen,
+ size_t outsize, const unsigned char *in,
+ size_t inlen);
+
+ /* Decryption */
+ int OP_asym_cipher_decrypt_init(void *ctx, void *provkey);
+ int OP_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 OP_asym_cipher_get_ctx_params(void *ctx, OSSL_PARAM params[]);
+ const OSSL_PARAM *OP_asym_cipher_gettable_ctx_params(void);
+ int OP_asym_cipher_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
+ const OSSL_PARAM *OP_asym_cipher_settable_ctx_params(void);
+
+=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_init_ex(3)>, L<EVP_PKEY_encrypt(3)>,
+L<EVP_PKEY_decrypt_init_ex(3)>, L<EVP_PKEY_decrypt(3)> (as well
+as 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_{name}_fn>, and a helper function to retrieve the
+function pointer from an B<OSSL_DISPATCH> element named
+B<OSSL_get_{name}>.
+For example, the "function" OP_asym_cipher_newctx() has these:
+
+ typedef void *(OSSL_OP_asym_cipher_newctx_fn)(void *provctx);
+ static ossl_inline OSSL_OP_asym_cipher_newctx_fn
+ OSSL_get_OP_asym_cipher_newctx(const OSSL_DISPATCH *opf);
+
+B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as
+macros in L<openssl-core_numbers.h(7)>, as follows:
+
+ OP_asym_cipher_newctx OSSL_FUNC_ASYM_CIPHER_NEWCTX
+ OP_asym_cipher_freectx OSSL_FUNC_ASYM_CIPHER_FREECTX
+ OP_asym_cipher_dupctx OSSL_FUNC_ASYM_CIPHER_DUPCTX
+
+ OP_asym_cipher_encrypt_init OSSL_FUNC_ASYM_CIPHER_ENCRYPT_INIT
+ OP_asym_cipher_encrypt OSSL_FUNC_ASYM_CIPHER_ENCRYPT
+
+ OP_asym_cipher_decrypt_init OSSL_FUNC_ASYM_CIPHER_DECRYPT_INIT
+ OP_asym_cipher_decrypt OSSL_FUNC_ASYM_CIPHER_DECRYPT
+
+ OP_asym_cipher_get_ctx_params OSSL_FUNC_ASYM_CIPHER_GET_CTX_PARAMS
+ OP_asym_cipher_gettable_ctx_params OSSL_FUNC_ASYM_CIPHER_GETTABLE_CTX_PARAMS
+ OP_asym_cipher_set_ctx_params OSSL_FUNC_ASYM_CIPHER_SET_CTX_PARAMS
+ OP_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
+OP_asym_cipher_newctx and OP_asym_cipher_freectx.
+It must also implement both of OP_asym_cipher_encrypt_init and
+OP_asym_cipher_encrypt, or both of OP_asym_cipher_decrypt_init and
+OP_asym_cipher_decrypt.
+OP_asym_cipher_get_ctx_params is optional but if it is present then so must
+OP_asym_cipher_gettable_ctx_params.
+Similarly, OP_asym_cipher_set_ctx_params is optional but if it is present then
+so must OP_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
+
+OP_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(3)>).
+
+OP_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.
+
+OP_asym_cipher_dupctx() should duplicate the provider side asymmetric cipher
+context in the I<ctx> parameter and return the duplicate copy.
+
+=head2 Encryption Functions
+
+OP_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 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)>.
+
+OP_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
+
+OP_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 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)>.
+
+OP_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 OP_asym_cipher_get_ctx_params() and OP_asym_cipher_set_ctx_params()
+functions.
+
+OP_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>.
+OP_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.
+
+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>
+
+=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-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 "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 "oaep-label-len" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL_LEN>) <size_t>
+
+Gets the length of an OAEP label when OAEP padding is in use.
+
+=back
+
+OP_asym_cipher_gettable_ctx_params() and OP_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 OP_asym_cipherget_ctx_params()
+and OP_asym_cipher_set_ctx_params() respectively.
+See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
+
+=head1 RETURN VALUES
+
+OP_asym_cipher_newctx() and OP_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 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
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