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.

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>.