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.\" ========================================================================
.\"
.IX Title "PROVIDER-MAC 7"
.TH PROVIDER-MAC 7 "2023-05-07" "3.0.9" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
provider\-mac \- The mac library <\-> provider functions
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& #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[]);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This documentation is primarily aimed at provider authors. See \fBprovider\fR\|(7)
for further information.
.PP
The \s-1MAC\s0 operation enables providers to implement mac algorithms and make
them available to applications via the \s-1API\s0 functions \fBEVP_MAC_init\fR\|(3),
\&\fBEVP_MAC_update\fR\|(3) and \fBEVP_MAC_final\fR\|(3).
.PP
All \*(L"functions\*(R" mentioned here are passed as function pointers between
\&\fIlibcrypto\fR and the provider in \s-1\fBOSSL_DISPATCH\s0\fR\|(3) arrays via
\&\s-1\fBOSSL_ALGORITHM\s0\fR\|(3) arrays that are returned by the provider's
\&\fBprovider_query_operation()\fR function
(see \*(L"Provider Functions\*(R" in \fBprovider\-base\fR\|(7)).
.PP
All these \*(L"functions\*(R" have a corresponding function type definition
named \fBOSSL_FUNC_{name}_fn\fR, and a helper function to retrieve the
function pointer from an \s-1\fBOSSL_DISPATCH\s0\fR\|(3) element named
\&\fBOSSL_FUNC_{name}\fR.
For example, the \*(L"function\*(R" \fBOSSL_FUNC_mac_newctx()\fR has these:
.PP
.Vb 3
\& 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);
.Ve
.PP
\&\s-1\fBOSSL_DISPATCH\s0\fR\|(3) arrays are indexed by numbers that are provided as
macros in \fBopenssl\-core_dispatch.h\fR\|(7), as follows:
.PP
.Vb 3
\& 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
.Ve
.PP
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: \fBOSSL_FUNC_mac_newctx()\fR, \fBOSSL_FUNC_mac_freectx()\fR, \fBOSSL_FUNC_mac_init()\fR,
\&\fBOSSL_FUNC_mac_update()\fR, \fBOSSL_FUNC_mac_final()\fR.
All other functions are optional.
.SS "Context Management Functions"
.IX Subsection "Context Management Functions"
\&\fBOSSL_FUNC_mac_newctx()\fR 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 \fIprovctx\fR is the provider context generated during provider
initialisation (see \fBprovider\fR\|(7)).
.PP
\&\fBOSSL_FUNC_mac_freectx()\fR is passed a pointer to the provider side mac context in
the \fImctx\fR parameter.
If it receives \s-1NULL\s0 as \fImctx\fR value, it should not do anything other than
return.
This function should free any resources associated with that context.
.PP
\&\fBOSSL_FUNC_mac_dupctx()\fR should duplicate the provider side mac context in the
\&\fImctx\fR parameter and return the duplicate copy.
.SS "Encryption/Decryption Functions"
.IX Subsection "Encryption/Decryption Functions"
\&\fBOSSL_FUNC_mac_init()\fR initialises a mac operation given a newly created provider
side mac context in the \fImctx\fR parameter.  The \fIparams\fR are set before setting
the \s-1MAC\s0 \fIkey\fR of \fIkeylen\fR bytes.
.PP
\&\fBOSSL_FUNC_mac_update()\fR is called to supply data for \s-1MAC\s0 computation of a previously
initialised mac operation.
The \fImctx\fR parameter contains a pointer to a previously initialised provider
side context.
\&\fBOSSL_FUNC_mac_update()\fR may be called multiple times for a single mac operation.
.PP
\&\fBOSSL_FUNC_mac_final()\fR completes the \s-1MAC\s0 computation started through previous
\&\fBOSSL_FUNC_mac_init()\fR and \fBOSSL_FUNC_mac_update()\fR calls.
The \fImctx\fR parameter contains a pointer to the provider side context.
The resulting \s-1MAC\s0 should be written to \fIout\fR and the amount of data written
to \fI*outl\fR, which should not exceed \fIoutsize\fR bytes.
The same expectations apply to \fIoutsize\fR as documented for
\&\fBEVP_MAC_final\fR\|(3).
.SS "Mac Parameters"
.IX Subsection "Mac Parameters"
See \s-1\fBOSSL_PARAM\s0\fR\|(3) for further details on the parameters structure used by
these functions.
.PP
\&\fBOSSL_FUNC_mac_get_params()\fR gets details of parameter values associated with the
provider algorithm and stores them in \fIparams\fR.
.PP
\&\fBOSSL_FUNC_mac_set_ctx_params()\fR sets mac parameters associated with the given
provider side mac context \fImctx\fR to \fIparams\fR.
Any parameter settings are additional to any that were previously set.
Passing \s-1NULL\s0 for \fIparams\fR should return true.
.PP
\&\fBOSSL_FUNC_mac_get_ctx_params()\fR gets details of currently set parameter values
associated with the given provider side mac context \fImctx\fR and stores them
in \fIparams\fR.
Passing \s-1NULL\s0 for \fIparams\fR should return true.
.PP
\&\fBOSSL_FUNC_mac_gettable_params()\fR, \fBOSSL_FUNC_mac_gettable_ctx_params()\fR,
and \fBOSSL_FUNC_mac_settable_ctx_params()\fR all return constant \s-1\fBOSSL_PARAM\s0\fR\|(3)
arrays as descriptors of the parameters that \fBOSSL_FUNC_mac_get_params()\fR,
\&\fBOSSL_FUNC_mac_get_ctx_params()\fR, and \fBOSSL_FUNC_mac_set_ctx_params()\fR
can handle, respectively.  \fBOSSL_FUNC_mac_gettable_ctx_params()\fR and
\&\fBOSSL_FUNC_mac_settable_ctx_params()\fR will return the parameters associated
with the provider side context \fImctx\fR in its current state if it is
not \s-1NULL.\s0  Otherwise, they return the parameters associated with the
provider side algorithm \fIprovctx\fR.
.PP
All \s-1MAC\s0 implementations are expected to handle the following parameters:
.IP "with \fBOSSL_FUNC_set_ctx_params()\fR:" 4
.IX Item "with OSSL_FUNC_set_ctx_params():"
.RS 4
.PD 0
.ie n .IP """key"" (\fB\s-1OSSL_MAC_PARAM_KEY\s0\fR) <octet string>" 4
.el .IP "``key'' (\fB\s-1OSSL_MAC_PARAM_KEY\s0\fR) <octet string>" 4
.IX Item "key (OSSL_MAC_PARAM_KEY) <octet string>"
.PD
Sets the key in the associated \s-1MAC\s0 ctx.  This is identical to passing a \fIkey\fR
argument to the \fBOSSL_FUNC_mac_init()\fR function.
.RE
.RS 4
.RE
.IP "with \fBOSSL_FUNC_get_params()\fR:" 4
.IX Item "with OSSL_FUNC_get_params():"
.RS 4
.PD 0
.ie n .IP """size"" (\fB\s-1OSSL_MAC_PARAM_SIZE\s0\fR) <integer>" 4
.el .IP "``size'' (\fB\s-1OSSL_MAC_PARAM_SIZE\s0\fR) <integer>" 4
.IX Item "size (OSSL_MAC_PARAM_SIZE) <integer>"
.PD
Can be used to get the default \s-1MAC\s0 size (which might be the only allowable
\&\s-1MAC\s0 size for the implementation).
.Sp
Note that some implementations allow setting the size that the resulting \s-1MAC\s0
should have as well, see the documentation of the implementation.
.RE
.RS 4
.ie n .IP """size"" (\fB\s-1OSSL_MAC_PARAM_BLOCK_SIZE\s0\fR) <integer>" 4
.el .IP "``size'' (\fB\s-1OSSL_MAC_PARAM_BLOCK_SIZE\s0\fR) <integer>" 4
.IX Item "size (OSSL_MAC_PARAM_BLOCK_SIZE) <integer>"
Can be used to get the \s-1MAC\s0 block size (if supported by the algorithm).
.RE
.RS 4
.RE
.SH "NOTES"
.IX Header "NOTES"
The \s-1MAC\s0 life-cycle is described in \fBlife_cycle\-rand\fR\|(7).  Providers should
ensure that the various transitions listed there are supported.  At some point
the \s-1EVP\s0 layer will begin enforcing the listed transitions.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBOSSL_FUNC_mac_newctx()\fR and \fBOSSL_FUNC_mac_dupctx()\fR should return the newly created
provider side mac context, or \s-1NULL\s0 on failure.
.PP
\&\fBOSSL_FUNC_mac_init()\fR, \fBOSSL_FUNC_mac_update()\fR, \fBOSSL_FUNC_mac_final()\fR, \fBOSSL_FUNC_mac_get_params()\fR,
\&\fBOSSL_FUNC_mac_get_ctx_params()\fR and \fBOSSL_FUNC_mac_set_ctx_params()\fR should return 1 for
success or 0 on error.
.PP
\&\fBOSSL_FUNC_mac_gettable_params()\fR, \fBOSSL_FUNC_mac_gettable_ctx_params()\fR and
\&\fBOSSL_FUNC_mac_settable_ctx_params()\fR should return a constant \s-1\fBOSSL_PARAM\s0\fR\|(3)
array, or \s-1NULL\s0 if none is offered.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBprovider\fR\|(7),
\&\s-1\fBEVP_MAC\-BLAKE2\s0\fR\|(7), \s-1\fBEVP_MAC\-CMAC\s0\fR\|(7), \s-1\fBEVP_MAC\-GMAC\s0\fR\|(7),
\&\s-1\fBEVP_MAC\-HMAC\s0\fR\|(7), \s-1\fBEVP_MAC\-KMAC\s0\fR\|(7), \fBEVP_MAC\-Poly1305\fR\|(7),
\&\fBEVP_MAC\-Siphash\fR\|(7),
\&\fBlife_cycle\-mac\fR\|(7), \s-1\fBEVP_MAC\s0\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
The provider \s-1MAC\s0 interface was introduced in OpenSSL 3.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2019\-2022 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.