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Title "PROVIDER-MAC 7ossl" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
provider-mac - The mac library <-> provider functions 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 Header "DESCRIPTION" This documentation is primarily aimed at provider authors. See provider\|(7) for further information.

The \s-1MAC\s0 operation enables providers to implement mac algorithms and make them available to applications via the \s-1API\s0 functions EVP_MAC_init\|(3), \fBEVP_MAC_update\|(3) and EVP_MAC_final\|(3).

All \*(L"functions\*(R" mentioned here are passed as function pointers between \fIlibcrypto and the provider in \s-1OSSL_DISPATCH\s0\|(3) arrays via \s-1OSSL_ALGORITHM\s0\|(3) arrays that are returned by the provider's \fBprovider_query_operation() function (see \*(L"Provider Functions\*(R" in provider-base\|(7)).

All these \*(L"functions\*(R" have a corresponding function type definition named OSSL_FUNC_{name}_fn, and a helper function to retrieve the function pointer from an \s-1OSSL_DISPATCH\s0\|(3) element named \fBOSSL_FUNC_{name}. For example, the \*(L"function\*(R" OSSL_FUNC_mac_newctx() has these:

.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

\s-1OSSL_DISPATCH\s0\|(3) arrays are indexed by numbers that are provided as macros in openssl-core_dispatch.h\|(7), as follows:

.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

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(), \fBOSSL_FUNC_mac_update(), OSSL_FUNC_mac_final(). All other functions are optional.

Subsection "Context Management Functions" \fBOSSL_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)).

\fBOSSL_FUNC_mac_freectx() is passed a pointer to the provider side mac context in the mctx parameter. If it receives \s-1NULL\s0 as mctx value, it should not do anything other than return. This function should free any resources associated with that context.

\fBOSSL_FUNC_mac_dupctx() should duplicate the provider side mac context in the \fImctx parameter and return the duplicate copy.

Subsection "Encryption/Decryption Functions" \fBOSSL_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 \s-1MAC\s0 key of keylen bytes.

\fBOSSL_FUNC_mac_update() is called to supply data for \s-1MAC\s0 computation of a previously initialised mac operation. The mctx parameter contains a pointer to a previously initialised provider side context. \fBOSSL_FUNC_mac_update() may be called multiple times for a single mac operation.

\fBOSSL_FUNC_mac_final() completes the \s-1MAC\s0 computation started through previous \fBOSSL_FUNC_mac_init() and OSSL_FUNC_mac_update() calls. The mctx parameter contains a pointer to the provider side context. The resulting \s-1MAC\s0 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 \fBEVP_MAC_final\|(3).

Subsection "Mac Parameters" See \s-1OSSL_PARAM\s0\|(3) for further details on the parameters structure used by these functions.

\fBOSSL_FUNC_mac_get_params() gets details of parameter values associated with the provider algorithm and stores them in params.

\fBOSSL_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 \s-1NULL\s0 for params should return true.

\fBOSSL_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 \s-1NULL\s0 for params should return true.

\fBOSSL_FUNC_mac_gettable_params(), OSSL_FUNC_mac_gettable_ctx_params(), and OSSL_FUNC_mac_settable_ctx_params() all return constant \s-1OSSL_PARAM\s0\|(3) arrays as descriptors of the parameters that OSSL_FUNC_mac_get_params(), \fBOSSL_FUNC_mac_get_ctx_params(), and OSSL_FUNC_mac_set_ctx_params() can handle, respectively. OSSL_FUNC_mac_gettable_ctx_params() and \fBOSSL_FUNC_mac_settable_ctx_params() will return the parameters associated with the provider side context mctx in its current state if it is not \s-1NULL.\s0 Otherwise, they return the parameters associated with the provider side algorithm provctx.

All \s-1MAC\s0 implementations are expected to handle the following parameters:

Item "with OSSL_FUNC_set_ctx_params():" Item "with OSSL_FUNC_get_params():" Header "NOTES" The \s-1MAC\s0 life-cycle is described in life_cycle-rand\|(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. Header "RETURN VALUES" \fBOSSL_FUNC_mac_newctx() and OSSL_FUNC_mac_dupctx() should return the newly created provider side mac context, or \s-1NULL\s0 on failure.

\fBOSSL_FUNC_mac_init(), OSSL_FUNC_mac_update(), OSSL_FUNC_mac_final(), OSSL_FUNC_mac_get_params(), \fBOSSL_FUNC_mac_get_ctx_params() and OSSL_FUNC_mac_set_ctx_params() should return 1 for success or 0 on error.

\fBOSSL_FUNC_mac_gettable_params(), OSSL_FUNC_mac_gettable_ctx_params() and \fBOSSL_FUNC_mac_settable_ctx_params() should return a constant \s-1OSSL_PARAM\s0\|(3) array, or \s-1NULL\s0 if none is offered.

Header "SEE ALSO" \fBprovider\|(7), \s-1EVP_MAC-BLAKE2\s0\|(7), \s-1EVP_MAC-CMAC\s0\|(7), \s-1EVP_MAC-GMAC\s0\|(7), \s-1EVP_MAC-HMAC\s0\|(7), \s-1EVP_MAC-KMAC\s0\|(7), EVP_MAC-Poly1305\|(7), \fBEVP_MAC-Siphash\|(7), \fBlife_cycle-mac\|(7), \s-1EVP_MAC\s0\|(3) Header "HISTORY" The provider \s-1MAC\s0 interface was introduced in OpenSSL 3.0. Header "COPYRIGHT" Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.

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>.