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Title "PROVIDER-DIGEST 7" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
provider-digest - The digest library <-> provider functions Header "SYNOPSIS" .Vb 2 #include <openssl/core_dispatch.h> #include <openssl/core_names.h> \& /* * Digests support the following function signatures in OSSL_DISPATCH arrays. * (The function signatures are not actual functions). */ \& /* Context management */ void *OSSL_FUNC_digest_newctx(void *provctx); void OSSL_FUNC_digest_freectx(void *dctx); void *OSSL_FUNC_digest_dupctx(void *dctx); \& /* Digest generation */ int OSSL_FUNC_digest_init(void *dctx, const OSSL_PARAM params[]); int OSSL_FUNC_digest_update(void *dctx, const unsigned char *in, size_t inl); int OSSL_FUNC_digest_final(void *dctx, unsigned char *out, size_t *outl, size_t outsz); int OSSL_FUNC_digest_digest(void *provctx, const unsigned char *in, size_t inl, unsigned char *out, size_t *outl, size_t outsz); \& /* Digest parameter descriptors */ const OSSL_PARAM *OSSL_FUNC_digest_gettable_params(void *provctx); \& /* Digest operation parameter descriptors */ const OSSL_PARAM *OSSL_FUNC_digest_gettable_ctx_params(void *dctx, void *provctx); const OSSL_PARAM *OSSL_FUNC_digest_settable_ctx_params(void *dctx, void *provctx); \& /* Digest parameters */ int OSSL_FUNC_digest_get_params(OSSL_PARAM params[]); \& /* Digest operation parameters */ int OSSL_FUNC_digest_set_ctx_params(void *dctx, const OSSL_PARAM params[]); int OSSL_FUNC_digest_get_ctx_params(void *dctx, OSSL_PARAM params[]); .Ve Header "DESCRIPTION" This documentation is primarily aimed at provider authors. See provider\|(7) for further information.

The \s-1DIGEST\s0 operation enables providers to implement digest algorithms and make them available to applications via the \s-1API\s0 functions EVP_DigestInit_ex\|(3), \fBEVP_DigestUpdate\|(3) and EVP_DigestFinal\|(3) (and other related functions).

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_digest_newctx() has these:

.Vb 3 typedef void *(OSSL_FUNC_digest_newctx_fn)(void *provctx); static ossl_inline OSSL_FUNC_digest_newctx_fn OSSL_FUNC_digest_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_digest_newctx OSSL_FUNC_DIGEST_NEWCTX OSSL_FUNC_digest_freectx OSSL_FUNC_DIGEST_FREECTX OSSL_FUNC_digest_dupctx OSSL_FUNC_DIGEST_DUPCTX \& OSSL_FUNC_digest_init OSSL_FUNC_DIGEST_INIT OSSL_FUNC_digest_update OSSL_FUNC_DIGEST_UPDATE OSSL_FUNC_digest_final OSSL_FUNC_DIGEST_FINAL OSSL_FUNC_digest_digest OSSL_FUNC_DIGEST_DIGEST \& OSSL_FUNC_digest_get_params OSSL_FUNC_DIGEST_GET_PARAMS OSSL_FUNC_digest_get_ctx_params OSSL_FUNC_DIGEST_GET_CTX_PARAMS OSSL_FUNC_digest_set_ctx_params OSSL_FUNC_DIGEST_SET_CTX_PARAMS \& OSSL_FUNC_digest_gettable_params OSSL_FUNC_DIGEST_GETTABLE_PARAMS OSSL_FUNC_digest_gettable_ctx_params OSSL_FUNC_DIGEST_GETTABLE_CTX_PARAMS OSSL_FUNC_digest_settable_ctx_params OSSL_FUNC_DIGEST_SETTABLE_CTX_PARAMS .Ve

A digest algorithm implementation may not implement all of these functions. In order to be usable all or none of OSSL_FUNC_digest_newctx, OSSL_FUNC_digest_freectx, OSSL_FUNC_digest_init, OSSL_FUNC_digest_update and OSSL_FUNC_digest_final should be implemented. All other functions are optional.

Subsection "Context Management Functions" \fBOSSL_FUNC_digest_newctx() should create and return a pointer to a provider side structure for holding context information during a digest operation. A pointer to this context will be passed back in a number of the other digest operation function calls. The parameter provctx is the provider context generated during provider initialisation (see provider\|(7)).

\fBOSSL_FUNC_digest_freectx() is passed a pointer to the provider side digest context in the dctx parameter. This function should free any resources associated with that context.

\fBOSSL_FUNC_digest_dupctx() should duplicate the provider side digest context in the \fIdctx parameter and return the duplicate copy.

Subsection "Digest Generation Functions" \fBOSSL_FUNC_digest_init() initialises a digest operation given a newly created provider side digest context in the dctx parameter. The params, if not \s-1NULL,\s0 should be set on the context in a manner similar to using OSSL_FUNC_digest_set_ctx_params().

\fBOSSL_FUNC_digest_update() is called to supply data to be digested as part of a previously initialised digest operation. The dctx parameter contains a pointer to a previously initialised provider side context. \fBOSSL_FUNC_digest_update() should digest inl bytes of data at the location pointed to by in. \fBOSSL_FUNC_digest_update() may be called multiple times for a single digest operation.

\fBOSSL_FUNC_digest_final() generates a digest started through previous OSSL_FUNC_digest_init() and OSSL_FUNC_digest_update() calls. The dctx parameter contains a pointer to the provider side context. The digest should be written to *out and the length of the digest to \fI*outl. The digest should not exceed outsz bytes.

\fBOSSL_FUNC_digest_digest() is a \*(L"oneshot\*(R" digest function. No provider side digest context is used. Instead the provider context that was created during provider initialisation is passed in the provctx parameter (see provider\|(7)). \fIinl bytes at in should be digested and the result should be stored at \fIout. The length of the digest should be stored in *outl which should not exceed outsz bytes.

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

\fBOSSL_FUNC_digest_get_params() gets details of the algorithm implementation and stores them in params.

\fBOSSL_FUNC_digest_set_ctx_params() sets digest operation parameters for the provider side digest context dctx to params. Any parameter settings are additional to any that were previously set. Passing \s-1NULL\s0 for params should return true.

\fBOSSL_FUNC_digest_get_ctx_params() gets digest operation details details from the given provider side digest context dctx and stores them in params. Passing \s-1NULL\s0 for params should return true.

\fBOSSL_FUNC_digest_gettable_params() returns a constant \s-1OSSL_PARAM\s0\|(3) array containing descriptors of the parameters that OSSL_FUNC_digest_get_params() can handle.

\fBOSSL_FUNC_digest_gettable_ctx_params() and \fBOSSL_FUNC_digest_settable_ctx_params() both return constant \s-1OSSL_PARAM\s0\|(3) arrays as descriptors of the parameters that \fBOSSL_FUNC_digest_get_ctx_params() and OSSL_FUNC_digest_set_ctx_params() can handle, respectively. The array is based on the current state of the provider side context if dctx is not \s-1NULL\s0 and on the provider side algorithm provctx otherwise.

Parameters currently recognised by built-in digests with this function are as follows. Not all parameters are relevant to, or are understood by all digests: Item "blocksize (OSSL_DIGEST_PARAM_BLOCK_SIZE) <unsigned integer>" The digest block size. The length of the \*(L"blocksize\*(R" parameter should not exceed that of a size_t. Item "size (OSSL_DIGEST_PARAM_SIZE) <unsigned integer>" The digest output size. The length of the \*(L"size\*(R" parameter should not exceed that of a size_t. Item "flags (OSSL_DIGEST_PARAM_FLAGS) <unsigned integer>" Diverse flags that describe exceptional behaviour for the digest:

Subsection "Digest Context Parameters" \fBOSSL_FUNC_digest_set_ctx_params() sets digest parameters associated with the given provider side digest context dctx to params. Any parameter settings are additional to any that were previously set. See \s-1OSSL_PARAM\s0\|(3) for further details on the parameters structure.

\fBOSSL_FUNC_digest_get_ctx_params() gets details of currently set parameters values associated with the give provider side digest context dctx and stores them in params. See \s-1OSSL_PARAM\s0\|(3) for further details on the parameters structure.

Header "RETURN VALUES" \fBOSSL_FUNC_digest_newctx() and OSSL_FUNC_digest_dupctx() should return the newly created provider side digest context, or \s-1NULL\s0 on failure.

\fBOSSL_FUNC_digest_init(), OSSL_FUNC_digest_update(), OSSL_FUNC_digest_final(), OSSL_FUNC_digest_digest(), \fBOSSL_FUNC_digest_set_params() and OSSL_FUNC_digest_get_params() should return 1 for success or 0 on error.

\fBOSSL_FUNC_digest_size() should return the digest size.

\fBOSSL_FUNC_digest_block_size() should return the block size of the underlying digest algorithm.

Header "BUGS" The EVP_Q_digest(), EVP_Digest() and EVP_DigestFinal_ex() \s-1API\s0 calls do not expect the digest size to be larger than \s-1EVP_MAX_MD_SIZE.\s0 Any algorithm which produces larger digests is unusable with those \s-1API\s0 calls. Header "SEE ALSO" \fBprovider\|(7), \s-1OSSL_PROVIDER-FIPS\s0\|(7), OSSL_PROVIDER-default\|(7), \fBOSSL_PROVIDER-legacy\|(7), \fBEVP_MD-common\|(7), \s-1EVP_MD-BLAKE2\s0\|(7), \s-1EVP_MD-MD2\s0\|(7), \s-1EVP_MD-MD4\s0\|(7), \s-1EVP_MD-MD5\s0\|(7), \s-1EVP_MD-MD5-SHA1\s0\|(7), \s-1EVP_MD-MDC2\s0\|(7), \s-1EVP_MD-RIPEMD160\s0\|(7), \s-1EVP_MD-SHA1\s0\|(7), \s-1EVP_MD-SHA2\s0\|(7), \s-1EVP_MD-SHA3\s0\|(7), \s-1EVP_MD-SHAKE\s0\|(7), \s-1EVP_MD-SM3\s0\|(7), \s-1EVP_MD-WHIRLPOOL\s0\|(7), \s-1EVP_MD-NULL\s0\|(7), \fBlife_cycle-digest\|(7), EVP_DigestInit\|(3) Header "HISTORY" The provider \s-1DIGEST\s0 interface was introduced in OpenSSL 3.0. Header "COPYRIGHT" Copyright 2019-2023 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>.