doc/man7/provider-digest.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 provider-digest - The digest library E<lt>-E<gt> provider functions

 =head1 SYNOPSIS

 =for openssl multiple includes

  #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[]);

 =head1 DESCRIPTION

 This documentation is primarily aimed at provider authors. See L<provider(7)>
 for further information.

 The DIGEST operation enables providers to implement digest algorithms and make
 them available to applications via the API functions L<EVP_DigestInit_ex(3)>,
 L<EVP_DigestUpdate(3)> and L<EVP_DigestFinal(3)> (and other related functions).

 All "functions" mentioned here are passed as function pointers between
 F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via
 B<OSSL_ALGORITHM> arrays that are returned by the provider's
 provider_query_operation() function
 (see L<provider-base(7)/Provider Functions>).

 All these "functions" have a corresponding function type definition
 named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
 function pointer from an B<OSSL_DISPATCH> element named
 B<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);

 B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as
 macros in L<openssl-core_dispatch.h(7)>, 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.

 =head2 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 I<provctx> is the provider context generated during provider
 initialisation (see L<provider(7)>).

 OSSL_FUNC_digest_freectx() is passed a pointer to the provider side digest context in
 the I<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
 I<dctx> parameter and return the duplicate copy.

 =head2 Digest Generation Functions

 OSSL_FUNC_digest_init() initialises a digest operation given a newly created
 provider side digest context in the I<dctx> parameter.
 The I<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 I<dctx> parameter contains a pointer to a previously initialised provider
 side context.
 OSSL_FUNC_digest_update() should digest I<inl> bytes of data at the location pointed to
 by I<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 I<dctx> parameter contains a pointer to the provider side context.
 The digest should be written to I<*out> and the length of the digest to
 I<*outl>.
 The digest should not exceed I<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 I<provctx> parameter (see L<provider(7)>).
 I<inl> bytes at I<in> should be digested and the result should be stored at
 I<out>. The length of the digest should be stored in I<*outl> which should not
 exceed I<outsz> bytes.

 =head2 Digest Parameters

 See L<OSSL_PARAM(3)> 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 I<params>.

 OSSL_FUNC_digest_set_ctx_params() sets digest operation parameters for the
 provider side digest context I<dctx> to I<params>.
 Any parameter settings are additional to any that were previously set.
 Passing NULL for I<params> should return true.

 OSSL_FUNC_digest_get_ctx_params() gets digest operation details details from
 the given provider side digest context I<dctx> and stores them in I<params>.
 Passing NULL for I<params> should return true.

 OSSL_FUNC_digest_gettable_params() returns a constant B<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
 B<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 I<dctx> is not NULL and on the provider
 side algorithm I<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:

 =over 4

 =item "blocksize" (B<OSSL_DIGEST_PARAM_BLOCK_SIZE>) <unsigned integer>

 The digest block size.
 The length of the "blocksize" parameter should not exceed that of a B<size_t>.

 =item "size" (B<OSSL_DIGEST_PARAM_SIZE>) <unsigned integer>

 The digest output size.
 The length of the "size" parameter should not exceed that of a B<size_t>.

 =item "flags" (B<OSSL_DIGEST_PARAM_FLAGS>) <unsigned integer>

 Diverse flags that describe exceptional behaviour for the digest:

 =over 4

 =item B<EVP_MD_FLAG_ONESHOT>

 This digest method can only handle one block of input.

 =item B<EVP_MD_FLAG_XOF>

 This digest method is an extensible-output function (XOF) and supports
 setting the B<OSSL_DIGEST_PARAM_XOFLEN> parameter.

 =item B<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.  I<Note: if
 combined with EVP_MD_FLAG_DIGALGID_ABSENT, the latter will override.>

 =item B<EVP_MD_FLAG_DIGALGID_ABSENT>

 When setting up a DigestAlgorithmIdentifier, this flag will have the
 parameter be left absent by default.  I<Note: if combined with
 EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.>

 =item B<EVP_MD_FLAG_DIGALGID_CUSTOM>

 Custom DigestAlgorithmIdentifier handling via ctrl, with
 B<EVP_MD_FLAG_DIGALGID_ABSENT> as default.  I<Note: if combined with
 EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.>
 Currently unused.

 =back

 The length of the "flags" parameter should equal that of an
 B<unsigned long int>.

 =back

 =head2 Digest Context Parameters

 OSSL_FUNC_digest_set_ctx_params() sets digest parameters associated with the
 given provider side digest context I<dctx> to I<params>.
 Any parameter settings are additional to any that were previously set.
 See L<OSSL_PARAM(3)> 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 I<dctx>
 and stores them in I<params>.
 See L<OSSL_PARAM(3)> for further details on the parameters structure.

 =head1 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.

 =head1 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.

 =head1 SEE ALSO

 L<provider(7)>, L<OSSL_PROVIDER-FIPS(7)>, L<OSSL_PROVIDER-default(7)>,
 L<OSSL_PROVIDER-legacy(7)>,
 L<EVP_MD-common(7)>, L<EVP_MD-BLAKE2(7)>, L<EVP_MD-MD2(7)>,
 L<EVP_MD-MD4(7)>, L<EVP_MD-MD5(7)>, L<EVP_MD-MD5-SHA1(7)>,
 L<EVP_MD-MDC2(7)>, L<EVP_MD-RIPEMD160(7)>, L<EVP_MD-SHA1(7)>,
 L<EVP_MD-SHA2(7)>, L<EVP_MD-SHA3(7)>, L<EVP_MD-KECCAK(7)>
 L<EVP_MD-SHAKE(7)>, L<EVP_MD-SM3(7)>, L<EVP_MD-WHIRLPOOL(7)>,
 L<life_cycle-digest(7)>, L<EVP_DigestInit(3)>

 =head1 HISTORY

 The provider DIGEST interface was introduced in OpenSSL 3.0.

 =head1 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
 L<https://www.openssl.org/source/license.html>.

 =cut
	=pod

	=head1 NAME

	provider-digest - The digest library E<lt>-E<gt> provider functions

	=head1 SYNOPSIS

	=for openssl multiple includes

	#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[]);

	=head1 DESCRIPTION

	This documentation is primarily aimed at provider authors. See L<provider(7)>
	for further information.

	The DIGEST operation enables providers to implement digest algorithms and make
	them available to applications via the API functions L<EVP_DigestInit_ex(3)>,
	L<EVP_DigestUpdate(3)> and L<EVP_DigestFinal(3)> (and other related functions).

	All "functions" mentioned here are passed as function pointers between
	F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via
	B<OSSL_ALGORITHM> arrays that are returned by the provider's
	provider_query_operation() function
	(see L<provider-base(7)/Provider Functions>).

	All these "functions" have a corresponding function type definition
	named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
	function pointer from an B<OSSL_DISPATCH> element named
	B<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);

	B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as
	macros in L<openssl-core_dispatch.h(7)>, 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.

	=head2 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 I<provctx> is the provider context generated during provider
	initialisation (see L<provider(7)>).

	OSSL_FUNC_digest_freectx() is passed a pointer to the provider side digest context in
	the I<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
	I<dctx> parameter and return the duplicate copy.

	=head2 Digest Generation Functions

	OSSL_FUNC_digest_init() initialises a digest operation given a newly created
	provider side digest context in the I<dctx> parameter.
	The I<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 I<dctx> parameter contains a pointer to a previously initialised provider
	side context.
	OSSL_FUNC_digest_update() should digest I<inl> bytes of data at the location pointed to
	by I<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 I<dctx> parameter contains a pointer to the provider side context.
	The digest should be written to I<*out> and the length of the digest to
	I<*outl>.
	The digest should not exceed I<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 I<provctx> parameter (see L<provider(7)>).
	I<inl> bytes at I<in> should be digested and the result should be stored at
	I<out>. The length of the digest should be stored in I<*outl> which should not
	exceed I<outsz> bytes.

	=head2 Digest Parameters

	See L<OSSL_PARAM(3)> 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 I<params>.

	OSSL_FUNC_digest_set_ctx_params() sets digest operation parameters for the
	provider side digest context I<dctx> to I<params>.
	Any parameter settings are additional to any that were previously set.
	Passing NULL for I<params> should return true.

	OSSL_FUNC_digest_get_ctx_params() gets digest operation details details from
	the given provider side digest context I<dctx> and stores them in I<params>.
	Passing NULL for I<params> should return true.

	OSSL_FUNC_digest_gettable_params() returns a constant B<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
	B<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 I<dctx> is not NULL and on the provider
	side algorithm I<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:

	=over 4

	=item "blocksize" (B<OSSL_DIGEST_PARAM_BLOCK_SIZE>) <unsigned integer>

	The digest block size.
	The length of the "blocksize" parameter should not exceed that of a B<size_t>.

	=item "size" (B<OSSL_DIGEST_PARAM_SIZE>) <unsigned integer>

	The digest output size.
	The length of the "size" parameter should not exceed that of a B<size_t>.

	=item "flags" (B<OSSL_DIGEST_PARAM_FLAGS>) <unsigned integer>

	Diverse flags that describe exceptional behaviour for the digest:

	=over 4

	=item B<EVP_MD_FLAG_ONESHOT>

	This digest method can only handle one block of input.

	=item B<EVP_MD_FLAG_XOF>

	This digest method is an extensible-output function (XOF) and supports
	setting the B<OSSL_DIGEST_PARAM_XOFLEN> parameter.

	=item B<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. I<Note: if
	combined with EVP_MD_FLAG_DIGALGID_ABSENT, the latter will override.>

	=item B<EVP_MD_FLAG_DIGALGID_ABSENT>

	When setting up a DigestAlgorithmIdentifier, this flag will have the
	parameter be left absent by default. I<Note: if combined with
	EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.>

	=item B<EVP_MD_FLAG_DIGALGID_CUSTOM>

	Custom DigestAlgorithmIdentifier handling via ctrl, with
	B<EVP_MD_FLAG_DIGALGID_ABSENT> as default. I<Note: if combined with
	EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.>
	Currently unused.

	=back

	The length of the "flags" parameter should equal that of an
	B<unsigned long int>.

	=back

	=head2 Digest Context Parameters

	OSSL_FUNC_digest_set_ctx_params() sets digest parameters associated with the
	given provider side digest context I<dctx> to I<params>.
	Any parameter settings are additional to any that were previously set.
	See L<OSSL_PARAM(3)> 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 I<dctx>
	and stores them in I<params>.
	See L<OSSL_PARAM(3)> for further details on the parameters structure.

	=head1 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.

	=head1 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.

	=head1 SEE ALSO

	L<provider(7)>, L<OSSL_PROVIDER-FIPS(7)>, L<OSSL_PROVIDER-default(7)>,
	L<OSSL_PROVIDER-legacy(7)>,
	L<EVP_MD-common(7)>, L<EVP_MD-BLAKE2(7)>, L<EVP_MD-MD2(7)>,
	L<EVP_MD-MD4(7)>, L<EVP_MD-MD5(7)>, L<EVP_MD-MD5-SHA1(7)>,
	L<EVP_MD-MDC2(7)>, L<EVP_MD-RIPEMD160(7)>, L<EVP_MD-SHA1(7)>,
	L<EVP_MD-SHA2(7)>, L<EVP_MD-SHA3(7)>, L<EVP_MD-KECCAK(7)>
	L<EVP_MD-SHAKE(7)>, L<EVP_MD-SM3(7)>, L<EVP_MD-WHIRLPOOL(7)>,
	L<life_cycle-digest(7)>, L<EVP_DigestInit(3)>

	=head1 HISTORY

	The provider DIGEST interface was introduced in OpenSSL 3.0.

	=head1 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
	L<https://www.openssl.org/source/license.html>.

	=cut