Provided by: openssl_3.3.1-2ubuntu2_amd64 
NAME
provider-mac - The mac library <-> provider functions
SYNOPSIS
#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_mac_newctx(void *provctx);
void OSSL_FUNC_mac_freectx(void *mctx);
void *OSSL_FUNC_mac_dupctx(void *src);
/* Encryption/decryption */
int OSSL_FUNC_mac_init(void *mctx, unsigned char *key, size_t keylen,
const OSSL_PARAM params[]);
int OSSL_FUNC_mac_update(void *mctx, const unsigned char *in, size_t inl);
int OSSL_FUNC_mac_final(void *mctx, unsigned char *out, size_t *outl, size_t outsize);
/* MAC parameter descriptors */
const OSSL_PARAM *OSSL_FUNC_mac_gettable_params(void *provctx);
const OSSL_PARAM *OSSL_FUNC_mac_gettable_ctx_params(void *mctx, void *provctx);
const OSSL_PARAM *OSSL_FUNC_mac_settable_ctx_params(void *mctx, void *provctx);
/* MAC parameters */
int OSSL_FUNC_mac_get_params(OSSL_PARAM params[]);
int OSSL_FUNC_mac_get_ctx_params(void *mctx, OSSL_PARAM params[]);
int OSSL_FUNC_mac_set_ctx_params(void *mctx, const OSSL_PARAM params[]);
DESCRIPTION
This documentation is primarily aimed at provider authors. See provider(7) for further
information.
The MAC operation enables providers to implement mac algorithms and make them available to
applications via the API functions EVP_MAC_init(3), EVP_MAC_update(3) and
EVP_MAC_final(3).
All "functions" mentioned here are passed as function pointers between libcrypto and the
provider in OSSL_DISPATCH(3) arrays via OSSL_ALGORITHM(3) arrays that are returned by the
provider's provider_query_operation() function (see "Provider Functions" in
provider-base(7)).
All these "functions" have a corresponding function type definition named
OSSL_FUNC_{name}_fn, and a helper function to retrieve the function pointer from an
OSSL_DISPATCH(3) element named OSSL_FUNC_{name}. For example, the "function"
OSSL_FUNC_mac_newctx() has these:
typedef void *(OSSL_FUNC_mac_newctx_fn)(void *provctx);
static ossl_inline OSSL_FUNC_mac_newctx_fn
OSSL_FUNC_mac_newctx(const OSSL_DISPATCH *opf);
OSSL_DISPATCH(3) arrays are indexed by numbers that are provided as macros in
openssl-core_dispatch.h(7), as follows:
OSSL_FUNC_mac_newctx OSSL_FUNC_MAC_NEWCTX
OSSL_FUNC_mac_freectx OSSL_FUNC_MAC_FREECTX
OSSL_FUNC_mac_dupctx OSSL_FUNC_MAC_DUPCTX
OSSL_FUNC_mac_init OSSL_FUNC_MAC_INIT
OSSL_FUNC_mac_update OSSL_FUNC_MAC_UPDATE
OSSL_FUNC_mac_final OSSL_FUNC_MAC_FINAL
OSSL_FUNC_mac_get_params OSSL_FUNC_MAC_GET_PARAMS
OSSL_FUNC_mac_get_ctx_params OSSL_FUNC_MAC_GET_CTX_PARAMS
OSSL_FUNC_mac_set_ctx_params OSSL_FUNC_MAC_SET_CTX_PARAMS
OSSL_FUNC_mac_gettable_params OSSL_FUNC_MAC_GETTABLE_PARAMS
OSSL_FUNC_mac_gettable_ctx_params OSSL_FUNC_MAC_GETTABLE_CTX_PARAMS
OSSL_FUNC_mac_settable_ctx_params OSSL_FUNC_MAC_SETTABLE_CTX_PARAMS
A mac algorithm implementation may not implement all of these functions. In order to be a
consistent set of functions, at least the following functions must be implemented:
OSSL_FUNC_mac_newctx(), OSSL_FUNC_mac_freectx(), OSSL_FUNC_mac_init(),
OSSL_FUNC_mac_update(), OSSL_FUNC_mac_final(). All other functions are optional.
Context Management Functions
OSSL_FUNC_mac_newctx() should create and return a pointer to a provider side structure for
holding context information during a mac operation. A pointer to this context will be
passed back in a number of the other mac operation function calls. The parameter provctx
is the provider context generated during provider initialisation (see provider(7)).
OSSL_FUNC_mac_freectx() is passed a pointer to the provider side mac context in the mctx
parameter. If it receives NULL as mctx value, it should not do anything other than
return. This function should free any resources associated with that context.
OSSL_FUNC_mac_dupctx() should duplicate the provider side mac context in the mctx
parameter and return the duplicate copy.
Encryption/Decryption Functions
OSSL_FUNC_mac_init() initialises a mac operation given a newly created provider side mac
context in the mctx parameter. The params are set before setting the MAC key of keylen
bytes.
OSSL_FUNC_mac_update() is called to supply data for MAC computation of a previously
initialised mac operation. The mctx parameter contains a pointer to a previously
initialised provider side context. OSSL_FUNC_mac_update() may be called multiple times
for a single mac operation.
OSSL_FUNC_mac_final() completes the MAC computation started through previous
OSSL_FUNC_mac_init() and OSSL_FUNC_mac_update() calls. The mctx parameter contains a
pointer to the provider side context. The resulting MAC should be written to out and the
amount of data written to *outl, which should not exceed outsize bytes. The same
expectations apply to outsize as documented for EVP_MAC_final(3).
Mac Parameters
See OSSL_PARAM(3) for further details on the parameters structure used by these functions.
OSSL_FUNC_mac_get_params() gets details of parameter values associated with the provider
algorithm and stores them in params.
OSSL_FUNC_mac_set_ctx_params() sets mac parameters associated with the given provider side
mac context mctx to params. Any parameter settings are additional to any that were
previously set. Passing NULL for params should return true.
OSSL_FUNC_mac_get_ctx_params() gets details of currently set parameter values associated
with the given provider side mac context mctx and stores them in params. Passing NULL for
params should return true.
OSSL_FUNC_mac_gettable_params(), OSSL_FUNC_mac_gettable_ctx_params(), and
OSSL_FUNC_mac_settable_ctx_params() all return constant OSSL_PARAM(3) arrays as
descriptors of the parameters that OSSL_FUNC_mac_get_params(),
OSSL_FUNC_mac_get_ctx_params(), and OSSL_FUNC_mac_set_ctx_params() can handle,
respectively. OSSL_FUNC_mac_gettable_ctx_params() and OSSL_FUNC_mac_settable_ctx_params()
will return the parameters associated with the provider side context mctx in its current
state if it is not NULL. Otherwise, they return the parameters associated with the
provider side algorithm provctx.
All MAC implementations are expected to handle the following parameters:
with OSSL_FUNC_set_ctx_params():
"key" (OSSL_MAC_PARAM_KEY) <octet string>
Sets the key in the associated MAC ctx. This is identical to passing a key
argument to the OSSL_FUNC_mac_init() function.
with OSSL_FUNC_get_params():
"size" (OSSL_MAC_PARAM_SIZE) <integer>
Can be used to get the default MAC size (which might be the only allowable MAC
size for the implementation).
Note that some implementations allow setting the size that the resulting MAC
should have as well, see the documentation of the implementation.
"size" (OSSL_MAC_PARAM_BLOCK_SIZE) <integer>
Can be used to get the MAC block size (if supported by the algorithm).
NOTES
The MAC life-cycle is described in life_cycle-rand(7). Providers should ensure that the
various transitions listed there are supported. At some point the EVP layer will begin
enforcing the listed transitions.
RETURN VALUES
OSSL_FUNC_mac_newctx() and OSSL_FUNC_mac_dupctx() should return the newly created provider
side mac context, or NULL on failure.
OSSL_FUNC_mac_init(), OSSL_FUNC_mac_update(), OSSL_FUNC_mac_final(),
OSSL_FUNC_mac_get_params(), OSSL_FUNC_mac_get_ctx_params() and
OSSL_FUNC_mac_set_ctx_params() should return 1 for success or 0 on error.
OSSL_FUNC_mac_gettable_params(), OSSL_FUNC_mac_gettable_ctx_params() and
OSSL_FUNC_mac_settable_ctx_params() should return a constant OSSL_PARAM(3) array, or NULL
if none is offered.
SEE ALSO
provider(7), EVP_MAC-BLAKE2(7), EVP_MAC-CMAC(7), EVP_MAC-GMAC(7), EVP_MAC-HMAC(7),
EVP_MAC-KMAC(7), EVP_MAC-Poly1305(7), EVP_MAC-Siphash(7), life_cycle-mac(7), EVP_MAC(3)
HISTORY
The provider MAC interface was introduced in OpenSSL 3.0.
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 <https://www.openssl.org/source/license.html>.