# phpman > man > PROVIDER-DIGEST(7SSL) [PROVIDER-DIGEST(7SSL)](https://www.chedong.com/phpMan.php/man/PROVIDER-DIGEST/7SSL/markdown) OpenSSL [PROVIDER-DIGEST(7SSL)](https://www.chedong.com/phpMan.php/man/PROVIDER-DIGEST/7SSL/markdown) ## NAME provider-digest - The digest library <-> provider functions ## SYNOPSIS #include #include /* * 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[]); ## DESCRIPTION This documentation is primarily aimed at provider authors. See [**provider**(7)](https://www.chedong.com/phpMan.php/man/provider/7/markdown) for further information. The DIGEST operation enables providers to implement digest algorithms and make them available to applications via the API functions **EVP**___**DigestInit**___**[ex**(3)](https://www.chedong.com/phpMan.php/man/ex/3/markdown), **EVP**___**[DigestUpdate**(3)](https://www.chedong.com/phpMan.php/man/DigestUpdate/3/markdown) and **EVP**___**[DigestFinal**(3)](https://www.chedong.com/phpMan.php/man/DigestFinal/3/markdown) (and other related functions). All "functions" mentioned here are passed as function pointers between _libcrypto_ and the provider in **OSSL**___**DISPATCH** arrays via **OSSL**___**ALGORITHM** arrays that are returned by the provider's **provider**___**query**___**operation()** function (see "Provider Functions" in [**provider-base**(7)](https://www.chedong.com/phpMan.php/man/provider-base/7/markdown)). 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** element named **OSSL**___**FUNC**___**{name}**. For example, the "function" **OSSL**___**FUNC**___**digest**___**newctx()** has these: typedef void *(OSSL_OSSL_FUNC_digest_newctx_fn)(void *provctx); static ossl_inline OSSL_OSSL_FUNC_digest_newctx_fn OSSL_FUNC_digest_newctx(const OSSL_DISPATCH *opf); **OSSL**___**DISPATCH** arrays are indexed by numbers that are provided as macros in **openssl-core**___**[dispatch.h**(7)](https://www.chedong.com/phpMan.php/man/dispatch.h/7/markdown), as follows: 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 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. ### Context Management Functions **OSSL**___**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)](https://www.chedong.com/phpMan.php/man/provider/7/markdown)). **OSSL**___**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. **OSSL**___**FUNC**___**digest**___**dupctx()** should duplicate the provider side digest context in the _dctx_ parameter and return the duplicate copy. ### Digest Generation Functions **OSSL**___**FUNC**___**digest**___**init()** initialises a digest operation given a newly created provider side digest context in the _dctx_ parameter. The _params_, if not NULL, should be set on the context in a manner similar to using **OSSL**___**FUNC**___**digest**___**set**___**ctx**___**params()**. **OSSL**___**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. **OSSL**___**FUNC**___**digest**___**update()** should digest _inl_ bytes of data at the location pointed to by _in_. **OSSL**___**FUNC**___**digest**___**update()** may be called multiple times for a single digest operation. **OSSL**___**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 _*outl_. The digest should not exceed _outsz_ bytes. **OSSL**___**FUNC**___**digest**___**digest()** is a "oneshot" 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)](https://www.chedong.com/phpMan.php/man/provider/7/markdown)). _inl_ bytes at _in_ should be digested and the result should be stored at _out_. The length of the digest should be stored in _*outl_ which should not exceed _outsz_ bytes. ### Digest Parameters See **OSSL**___**[PARAM**(3)](https://www.chedong.com/phpMan.php/man/PARAM/3/markdown) for further details on the parameters structure used by these functions. **OSSL**___**FUNC**___**digest**___**get**___**params()** gets details of the algorithm implementation and stores them in _params_. **OSSL**___**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 NULL for _params_ should return true. **OSSL**___**FUNC**___**digest**___**get**___**ctx**___**params()** gets digest operation details details from the given provider side digest context _dctx_ and stores them in _params_. Passing NULL for _params_ should return true. **OSSL**___**FUNC**___**digest**___**gettable**___**params()** returns a constant **OSSL**___**PARAM** array containing descriptors of the parameters that **OSSL**___**FUNC**___**digest**___**get**___**params()** can handle. **OSSL**___**FUNC**___**digest**___**gettable**___**ctx**___**params()** and **OSSL**___**FUNC**___**digest**___**settable**___**ctx**___**params()** both return constant **OSSL**___**PARAM** arrays as descriptors of the parameters that **OSSL**___**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 NULL 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: "blocksize" (**OSSL**___**DIGEST**___**PARAM**___**BLOCK**___**SIZE**) The digest block size. The length of the "blocksize" parameter should not exceed that of a **size**___**t**. "size" (**OSSL**___**DIGEST**___**PARAM**___**SIZE**) The digest output size. The length of the "size" parameter should not exceed that of a **size**___**t**. "flags" (**OSSL**___**DIGEST**___**PARAM**___**FLAGS**) Diverse flags that describe exceptional behaviour for the digest: **EVP**___**MD**___**FLAG**___**ONESHOT** This digest method can only handle one block of input. **EVP**___**MD**___**FLAG**___**XOF** This digest method is an extensible-output function (XOF) and supports setting the **OSSL**___**DIGEST**___**PARAM**___**XOFLEN** parameter. **EVP**___**MD**___**FLAG**___**DIGALGID**___**NULL** When setting up a DigestAlgorithmIdentifier, this flag will have the parameter set to NULL by default. Use this for PKCS#1. _Note:_ _if_ _combined_ _with_ _EVP_MD_FLAG_DIGALGID_ABSENT,_ _the_ _latter_ _will_ _override._ **EVP**___**MD**___**FLAG**___**DIGALGID**___**ABSENT** When setting up a DigestAlgorithmIdentifier, this flag will have the parameter be left absent by default. _Note:_ _if_ _combined_ _with_ _EVP_MD_FLAG_DIGALGID_NULL,_ _the_ _latter_ _will_ _be_ _overridden._ **EVP**___**MD**___**FLAG**___**DIGALGID**___**CUSTOM** Custom DigestAlgorithmIdentifier handling via ctrl, with **EVP**___**MD**___**FLAG**___**DIGALGID**___**ABSENT** as default. _Note:_ _if_ _combined_ _with_ _EVP_MD_FLAG_DIGALGID_NULL,_ _the_ _latter_ _will_ _be_ _overridden._ Currently unused. The length of the "flags" parameter should equal that of an **unsigned** **long** **int**. ### Digest Context Parameters **OSSL**___**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 **OSSL**___**[PARAM**(3)](https://www.chedong.com/phpMan.php/man/PARAM/3/markdown) for further details on the parameters structure. **OSSL**___**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 **OSSL**___**[PARAM**(3)](https://www.chedong.com/phpMan.php/man/PARAM/3/markdown) for further details on the parameters structure. ## RETURN VALUES **OSSL**___**FUNC**___**digest**___**newctx()** and **OSSL**___**FUNC**___**digest**___**dupctx()** should return the newly created provider side digest context, or NULL on failure. **OSSL**___**FUNC**___**digest**___**init()**, **OSSL**___**FUNC**___**digest**___**update()**, **OSSL**___**FUNC**___**digest**___**final()**, **OSSL**___**FUNC**___**digest**___**digest()**, **OSSL**___**FUNC**___**digest**___**set**___**params()** and **OSSL**___**FUNC**___**digest**___**get**___**params()** should return 1 for success or 0 on error. **OSSL**___**FUNC**___**digest**___**size()** should return the digest size. **OSSL**___**FUNC**___**digest**___**block**___**size()** should return the block size of the underlying digest algorithm. ## BUGS The **EVP**___**Q**___**digest()**, **EVP**___**Digest()** and **EVP**___**DigestFinal**___**ex()** API calls do not expect the digest size to be larger than EVP_MAX_MD_SIZE. Any algorithm which produces larger digests is unusable with those API calls. ## SEE ALSO [**provider**(7)](https://www.chedong.com/phpMan.php/man/provider/7/markdown), **OSSL**___**[PROVIDER-FIPS**(7)](https://www.chedong.com/phpMan.php/man/PROVIDER-FIPS/7/markdown), **OSSL**___**[PROVIDER-default**(7)](https://www.chedong.com/phpMan.php/man/PROVIDER-default/7/markdown), **OSSL**___**[PROVIDER-legacy**(7)](https://www.chedong.com/phpMan.php/man/PROVIDER-legacy/7/markdown), **EVP**___**[MD-common**(7)](https://www.chedong.com/phpMan.php/man/MD-common/7/markdown), **EVP**___**[MD-BLAKE2**(7)](https://www.chedong.com/phpMan.php/man/MD-BLAKE2/7/markdown), **EVP**___**[MD-MD2**(7)](https://www.chedong.com/phpMan.php/man/MD-MD2/7/markdown), **EVP**___**[MD-MD4**(7)](https://www.chedong.com/phpMan.php/man/MD-MD4/7/markdown), **EVP**___**[MD-MD5**(7)](https://www.chedong.com/phpMan.php/man/MD-MD5/7/markdown), **EVP**___**[MD-MD5-SHA1**(7)](https://www.chedong.com/phpMan.php/man/MD-MD5-SHA1/7/markdown), **EVP**___**[MD-MDC2**(7)](https://www.chedong.com/phpMan.php/man/MD-MDC2/7/markdown), **EVP**___**[MD-RIPEMD160**(7)](https://www.chedong.com/phpMan.php/man/MD-RIPEMD160/7/markdown), **EVP**___**[MD-SHA1**(7)](https://www.chedong.com/phpMan.php/man/MD-SHA1/7/markdown), **EVP**___**[MD-SHA2**(7)](https://www.chedong.com/phpMan.php/man/MD-SHA2/7/markdown), **EVP**___**[MD-SHA3**(7)](https://www.chedong.com/phpMan.php/man/MD-SHA3/7/markdown), **EVP**___**[MD-SHAKE**(7)](https://www.chedong.com/phpMan.php/man/MD-SHAKE/7/markdown), **EVP**___**[MD-SM3**(7)](https://www.chedong.com/phpMan.php/man/MD-SM3/7/markdown), **EVP**___**[MD-WHIRLPOOL**(7)](https://www.chedong.com/phpMan.php/man/MD-WHIRLPOOL/7/markdown), **life**___**[cycle-digest**(7)](https://www.chedong.com/phpMan.php/man/cycle-digest/7/markdown), **EVP**___**[DigestInit**(3)](https://www.chedong.com/phpMan.php/man/DigestInit/3/markdown) ## HISTORY The provider DIGEST 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 <>. 3.0.2 2026-04-07 [PROVIDER-DIGEST(7SSL)](https://www.chedong.com/phpMan.php/man/PROVIDER-DIGEST/7SSL/markdown)