provider-digest - The digest library <-> provider functions
#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[]);
This documentation is primarily aimed at provider authors. See
provider(7) 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),
EVP_DigestUpdate(3) and
EVP_DigestFinal(3) (and other related functions).
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_digest_newctx() has these:
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);
OSSL_DISPATCH(3) arrays are indexed by numbers that are provided as
macros in
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.
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)).
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.
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)).
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.
See
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
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(3) 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(3) 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)
<unsigned integer>
- The digest block size. The length of the
"blocksize" parameter should not exceed that of a
size_t.
- "size" (OSSL_DIGEST_PARAM_SIZE)
<unsigned integer>
- The digest output size. The length of the "size"
parameter should not exceed that of a size_t.
- "flags" (OSSL_DIGEST_PARAM_FLAGS)
<unsigned integer>
- 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.
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) 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) for
further details on the parameters structure.
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.
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.
provider(7),
OSSL_PROVIDER-FIPS(7),
OSSL_PROVIDER-default(7),
OSSL_PROVIDER-legacy(7),
EVP_MD-common(7),
EVP_MD-BLAKE2(7),
EVP_MD-MD2(7),
EVP_MD-MD4(7),
EVP_MD-MD5(7),
EVP_MD-MD5-SHA1(7),
EVP_MD-MDC2(7),
EVP_MD-RIPEMD160(7),
EVP_MD-SHA1(7),
EVP_MD-SHA2(7),
EVP_MD-SHA3(7),
EVP_MD-SHAKE(7),
EVP_MD-SM3(7),
EVP_MD-WHIRLPOOL(7),
EVP_MD-NULL(7),
life_cycle-digest(7),
EVP_DigestInit(3)
The provider DIGEST interface was introduced in OpenSSL 3.0.
Copyright 2019-2023 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>.