Updated: 2022/Sep/29
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PROVIDER-MAC(7) OpenSSL PROVIDER-MAC(7)
NAME
provider-mac - The mac library <-> provider functions
LIBRARY
libcrypto, -lcrypto
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 2019-2022 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>.
3.0.12 2023-05-07 PROVIDER-MAC(7)