EVP_MD_fetch, EVP_MD_up_ref, EVP_MD_free, EVP_MD_get_params,
EVP_MD_gettable_params, EVP_MD_CTX_new, EVP_MD_CTX_reset, EVP_MD_CTX_free,
EVP_MD_CTX_copy, EVP_MD_CTX_copy_ex, EVP_MD_CTX_ctrl, EVP_MD_CTX_set_params,
EVP_MD_CTX_get_params, EVP_MD_settable_ctx_params, EVP_MD_gettable_ctx_params,
EVP_MD_CTX_settable_params, EVP_MD_CTX_gettable_params, EVP_MD_CTX_set_flags,
EVP_MD_CTX_clear_flags, EVP_MD_CTX_test_flags, EVP_Q_digest, EVP_Digest,
EVP_DigestInit_ex2, EVP_DigestInit_ex, EVP_DigestInit, EVP_DigestUpdate,
EVP_DigestFinal_ex, EVP_DigestFinalXOF, EVP_DigestFinal, EVP_MD_is_a,
EVP_MD_get0_name, EVP_MD_get0_description, EVP_MD_names_do_all,
EVP_MD_get0_provider, EVP_MD_get_type, EVP_MD_get_pkey_type, EVP_MD_get_size,
EVP_MD_get_block_size, EVP_MD_get_flags, EVP_MD_CTX_get0_name, EVP_MD_CTX_md,
EVP_MD_CTX_get0_md, EVP_MD_CTX_get1_md, EVP_MD_CTX_get_type,
EVP_MD_CTX_get_size, EVP_MD_CTX_get_block_size, EVP_MD_CTX_get0_md_data,
EVP_MD_CTX_update_fn, EVP_MD_CTX_set_update_fn, EVP_md_null,
EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj,
EVP_MD_CTX_get_pkey_ctx, EVP_MD_CTX_set_pkey_ctx, EVP_MD_do_all_provided,
EVP_MD_type, EVP_MD_nid, EVP_MD_name, EVP_MD_pkey_type, EVP_MD_size,
EVP_MD_block_size, EVP_MD_flags, EVP_MD_CTX_size, EVP_MD_CTX_block_size,
EVP_MD_CTX_type, EVP_MD_CTX_pkey_ctx, EVP_MD_CTX_md_data - EVP digest routines
#include <openssl/evp.h>
EVP_MD *EVP_MD_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
const char *properties);
int EVP_MD_up_ref(EVP_MD *md);
void EVP_MD_free(EVP_MD *md);
int EVP_MD_get_params(const EVP_MD *digest, OSSL_PARAM params[]);
const OSSL_PARAM *EVP_MD_gettable_params(const EVP_MD *digest);
EVP_MD_CTX *EVP_MD_CTX_new(void);
int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
void EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void* p2);
int EVP_MD_CTX_get_params(EVP_MD_CTX *ctx, OSSL_PARAM params[]);
int EVP_MD_CTX_set_params(EVP_MD_CTX *ctx, const OSSL_PARAM params[]);
const OSSL_PARAM *EVP_MD_settable_ctx_params(const EVP_MD *md);
const OSSL_PARAM *EVP_MD_gettable_ctx_params(const EVP_MD *md);
const OSSL_PARAM *EVP_MD_CTX_settable_params(EVP_MD_CTX *ctx);
const OSSL_PARAM *EVP_MD_CTX_gettable_params(EVP_MD_CTX *ctx);
void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);
void EVP_MD_CTX_clear_flags(EVP_MD_CTX *ctx, int flags);
int EVP_MD_CTX_test_flags(const EVP_MD_CTX *ctx, int flags);
int EVP_Q_digest(OSSL_LIB_CTX *libctx, const char *name, const char *propq,
const void *data, size_t datalen,
unsigned char *md, size_t *mdlen);
int EVP_Digest(const void *data, size_t count, unsigned char *md,
unsigned int *size, const EVP_MD *type, ENGINE *impl);
int EVP_DigestInit_ex2(EVP_MD_CTX *ctx, const EVP_MD *type,
const OSSL_PARAM params[]);
int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *md, size_t len);
int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);
int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
int EVP_MD_CTX_copy(EVP_MD_CTX *out, EVP_MD_CTX *in);
const char *EVP_MD_get0_name(const EVP_MD *md);
const char *EVP_MD_get0_description(const EVP_MD *md);
int EVP_MD_is_a(const EVP_MD *md, const char *name);
int EVP_MD_names_do_all(const EVP_MD *md,
void (*fn)(const char *name, void *data),
void *data);
const OSSL_PROVIDER *EVP_MD_get0_provider(const EVP_MD *md);
int EVP_MD_get_type(const EVP_MD *md);
int EVP_MD_get_pkey_type(const EVP_MD *md);
int EVP_MD_get_size(const EVP_MD *md);
int EVP_MD_get_block_size(const EVP_MD *md);
unsigned long EVP_MD_get_flags(const EVP_MD *md);
const EVP_MD *EVP_MD_CTX_get0_md(const EVP_MD_CTX *ctx);
EVP_MD *EVP_MD_CTX_get1_md(EVP_MD_CTX *ctx);
const char *EVP_MD_CTX_get0_name(const EVP_MD_CTX *ctx);
int EVP_MD_CTX_get_size(const EVP_MD_CTX *ctx);
int EVP_MD_CTX_get_block_size(const EVP_MD_CTX *ctx);
int EVP_MD_CTX_get_type(const EVP_MD_CTX *ctx);
void *EVP_MD_CTX_get0_md_data(const EVP_MD_CTX *ctx);
const EVP_MD *EVP_md_null(void);
const EVP_MD *EVP_get_digestbyname(const char *name);
const EVP_MD *EVP_get_digestbynid(int type);
const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
EVP_PKEY_CTX *EVP_MD_CTX_get_pkey_ctx(const EVP_MD_CTX *ctx);
void EVP_MD_CTX_set_pkey_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pctx);
void EVP_MD_do_all_provided(OSSL_LIB_CTX *libctx,
void (*fn)(EVP_MD *mac, void *arg),
void *arg);
#define EVP_MD_type EVP_MD_get_type
#define EVP_MD_nid EVP_MD_get_type
#define EVP_MD_name EVP_MD_get0_name
#define EVP_MD_pkey_type EVP_MD_get_pkey_type
#define EVP_MD_size EVP_MD_get_size
#define EVP_MD_block_size EVP_MD_get_block_size
#define EVP_MD_flags EVP_MD_get_flags
#define EVP_MD_CTX_size EVP_MD_CTX_get_size
#define EVP_MD_CTX_block_size EVP_MD_CTX_get_block_size
#define EVP_MD_CTX_type EVP_MD_CTX_get_type
#define EVP_MD_CTX_pkey_ctx EVP_MD_CTX_get_pkey_ctx
#define EVP_MD_CTX_md_data EVP_MD_CTX_get0_md_data
The following functions have been deprecated since OpenSSL 3.0, and can be
hidden entirely by defining
OPENSSL_API_COMPAT with a suitable version
value, see
openssl_user_macros(7):
const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
int (*EVP_MD_CTX_update_fn(EVP_MD_CTX *ctx))(EVP_MD_CTX *ctx,
const void *data, size_t count);
void EVP_MD_CTX_set_update_fn(EVP_MD_CTX *ctx,
int (*update)(EVP_MD_CTX *ctx,
const void *data, size_t count));
The EVP digest routines are a high-level interface to message digests, and
should be used instead of the digest-specific functions.
The
EVP_MD type is a structure for digest method implementation.
- EVP_MD_fetch()
- Fetches the digest implementation for the given
algorithm from any provider offering it, within the criteria given
by the properties. See "ALGORITHM FETCHING" in
crypto(7) for further information.
The returned value must eventually be freed with EVP_MD_free().
Fetched EVP_MD structures are reference counted.
- EVP_MD_up_ref()
- Increments the reference count for an EVP_MD
structure.
- EVP_MD_free()
- Decrements the reference count for the fetched
EVP_MD structure. If the reference count drops to 0 then the
structure is freed.
- EVP_MD_CTX_new()
- Allocates and returns a digest context.
- EVP_MD_CTX_reset()
- Resets the digest context ctx. This can be used to
reuse an already existing context.
- EVP_MD_CTX_free()
- Cleans up digest context ctx and frees up the space
allocated to it.
- EVP_MD_CTX_ctrl()
-
This is a legacy method.
EVP_MD_CTX_set_params() and
EVP_MD_CTX_get_params() is the mechanism that
should be used to set and get parameters that are used by
providers.
Performs digest-specific control actions on context ctx. The control
command is indicated in cmd and any additional arguments in
p1 and p2. EVP_MD_CTX_ctrl() must be called after
EVP_DigestInit_ex2(). Other restrictions may apply depending on the
control type and digest implementation.
If this function happens to be used with a fetched EVP_MD, it will
translate the controls that are known to OpenSSL into OSSL_PARAM(3)
parameters with keys defined by OpenSSL and call
EVP_MD_CTX_get_params() or EVP_MD_CTX_set_params() as is
appropriate for each control command.
See "CONTROLS" below for more information, including what
translations are being done.
- EVP_MD_get_params()
- Retrieves the requested list of params from a MD
md. See "PARAMETERS" below for more information.
- EVP_MD_CTX_get_params()
- Retrieves the requested list of params from a MD
context ctx. See "PARAMETERS" below for more
information.
- EVP_MD_CTX_set_params()
- Sets the list of params into a MD context
ctx. See "PARAMETERS" below for more information.
- EVP_MD_gettable_params()
- Get a constant OSSL_PARAM(3) array that describes
the retrievable parameters that can be used with
EVP_MD_get_params().
-
EVP_MD_gettable_ctx_params(),
EVP_MD_CTX_gettable_params()
- Get a constant OSSL_PARAM(3) array that describes
the retrievable parameters that can be used with
EVP_MD_CTX_get_params(). EVP_MD_gettable_ctx_params()
returns the parameters that can be retrieved from the algorithm, whereas
EVP_MD_CTX_gettable_params() returns the parameters that can be
retrieved in the context's current state.
-
EVP_MD_settable_ctx_params(),
EVP_MD_CTX_settable_params()
- Get a constant OSSL_PARAM(3) array that describes
the settable parameters that can be used with
EVP_MD_CTX_set_params(). EVP_MD_settable_ctx_params()
returns the parameters that can be set from the algorithm, whereas
EVP_MD_CTX_settable_params() returns the parameters that can be set
in the context's current state.
-
EVP_MD_CTX_set_flags(),
EVP_MD_CTX_clear_flags(), EVP_MD_CTX_test_flags()
- Sets, clears and tests ctx flags. See
"FLAGS" below for more information.
-
EVP_Q_digest() is a quick one-shot digest
function.
- It hashes datalen bytes of data at data using
the digest algorithm name, which is fetched using the optional
libctx and propq parameters. The digest value is placed in
md and its length is written at mdlen if the pointer is not
NULL. At most EVP_MAX_MD_SIZE bytes will be written.
- EVP_Digest()
- A wrapper around the Digest Init_ex, Update and Final_ex
functions. Hashes count bytes of data at data using a digest
type from ENGINE impl. The digest value is placed in
md and its length is written at size if the pointer is not
NULL. At most EVP_MAX_MD_SIZE bytes will be written. If impl
is NULL the default implementation of digest type is used.
- EVP_DigestInit_ex2()
- Sets up digest context ctx to use a digest
type. type is typically supplied by a function such as
EVP_sha1(), or a value explicitly fetched with
EVP_MD_fetch().
The parameters params are set on the context after initialisation.
The type parameter can be NULL if ctx has been already
initialized with another EVP_DigestInit_ex() call and has not been
reset with EVP_MD_CTX_reset().
- EVP_DigestInit_ex()
- Sets up digest context ctx to use a digest
type. type is typically supplied by a function such as
EVP_sha1(), or a value explicitly fetched with
EVP_MD_fetch().
If impl is non-NULL, its implementation of the digest type is
used if there is one, and if not, the default implementation is used.
The type parameter can be NULL if ctx has been already
initialized with another EVP_DigestInit_ex() call and has not been
reset with EVP_MD_CTX_reset().
- EVP_DigestUpdate()
- Hashes cnt bytes of data at d into the digest
context ctx. This function can be called several times on the same
ctx to hash additional data.
- EVP_DigestFinal_ex()
- Retrieves the digest value from ctx and places it in
md. If the s parameter is not NULL then the number of bytes
of data written (i.e. the length of the digest) will be written to the
integer at s, at most EVP_MAX_MD_SIZE bytes will be written.
After calling EVP_DigestFinal_ex() no additional calls to
EVP_DigestUpdate() can be made, but EVP_DigestInit_ex2() can
be called to initialize a new digest operation.
- EVP_DigestFinalXOF()
- Interfaces to extendable-output functions, XOFs, such as
SHAKE128 and SHAKE256. It retrieves the digest value from ctx and
places it in len-sized md. After calling this function no
additional calls to EVP_DigestUpdate() can be made, but
EVP_DigestInit_ex2() can be called to initialize a new
operation.
- EVP_MD_CTX_copy_ex()
- Can be used to copy the message digest state from in
to out. This is useful if large amounts of data are to be hashed
which only differ in the last few bytes.
- EVP_DigestInit()
- Behaves in the same way as EVP_DigestInit_ex2()
except it doesn't set any parameters and calls EVP_MD_CTX_reset()
so it cannot be used with an type of NULL.
- EVP_DigestFinal()
- Similar to EVP_DigestFinal_ex() except after
computing the digest the digest context ctx is automatically
cleaned up with EVP_MD_CTX_reset().
- EVP_MD_CTX_copy()
- Similar to EVP_MD_CTX_copy_ex() except the
destination out does not have to be initialized.
- EVP_MD_is_a()
- Returns 1 if md is an implementation of an algorithm
that's identifiable with name, otherwise 0.
If md is a legacy digest (it's the return value from the likes of
EVP_sha256() rather than the result of an EVP_MD_fetch()),
only cipher names registered with the default library context (see
OSSL_LIB_CTX(3)) will be considered.
-
EVP_MD_get0_name(),
EVP_MD_CTX_get0_name()
- Return the name of the given message digest. For fetched
message digests with multiple names, only one of them is returned; it's
recommended to use EVP_MD_names_do_all() instead.
- EVP_MD_names_do_all()
- Traverses all names for the md, and calls fn
with each name and data. This is only useful with fetched
EVP_MDs.
- EVP_MD_get0_description()
- Returns a description of the digest, meant for display and
human consumption. The description is at the discretion of the digest
implementation.
- EVP_MD_get0_provider()
- Returns an OSSL_PROVIDER pointer to the provider
that implements the given EVP_MD.
-
EVP_MD_get_size(), EVP_MD_CTX_get_size()
- Return the size of the message digest when passed an
EVP_MD or an EVP_MD_CTX structure, i.e. the size of the
hash.
-
EVP_MD_get_block_size(),
EVP_MD_CTX_get_block_size()
- Return the block size of the message digest when passed an
EVP_MD or an EVP_MD_CTX structure.
-
EVP_MD_get_type(), EVP_MD_CTX_get_type()
- Return the NID of the OBJECT IDENTIFIER representing the
given message digest when passed an EVP_MD structure. For example,
"EVP_MD_get_type(EVP_sha1())" returns NID_sha1. This
function is normally used when setting ASN1 OIDs.
- EVP_MD_CTX_get0_md_data()
- Return the digest method private data for the passed
EVP_MD_CTX. The space is allocated by OpenSSL and has the size
originally set with EVP_MD_meth_set_app_datasize().
-
EVP_MD_CTX_get0_md(),
EVP_MD_CTX_get1_md()
-
EVP_MD_CTX_get0_md() returns the EVP_MD
structure corresponding to the passed EVP_MD_CTX. This will be the
same EVP_MD object originally passed to EVP_DigestInit_ex2()
(or other similar function) when the EVP_MD_CTX was first initialised.
Note that where explicit fetch is in use (see EVP_MD_fetch(3)) the
value returned from this function will not have its reference count
incremented and therefore it should not be used after the EVP_MD_CTX is
freed. EVP_MD_CTX_get1_md() is the same except the ownership is
passed to the caller and is from the passed EVP_MD_CTX.
- EVP_MD_CTX_set_update_fn()
- Sets the update function for ctx to update.
This is the function that is called by EVP_DigestUpdate(). If not
set, the update function from the EVP_MD type specified at
initialization is used.
- EVP_MD_CTX_update_fn()
- Returns the update function for ctx.
- EVP_MD_get_flags()
- Returns the md flags. Note that these are different
from the EVP_MD_CTX ones. See EVP_MD_meth_set_flags(3) for
more information.
- EVP_MD_get_pkey_type()
- Returns the NID of the public key signing algorithm
associated with this digest. For example EVP_sha1() is associated
with RSA so this will return NID_sha1WithRSAEncryption. Since
digests and signature algorithms are no longer linked this function is
only retained for compatibility reasons.
- EVP_md_null()
- A "null" message digest that does nothing: i.e.
the hash it returns is of zero length.
-
EVP_get_digestbyname(),
EVP_get_digestbynid(), EVP_get_digestbyobj()
- Returns an EVP_MD structure when passed a digest
name, a digest NID or an ASN1_OBJECT structure respectively.
The EVP_get_digestbyname() function is present for backwards
compatibility with OpenSSL prior to version 3 and is different to the
EVP_MD_fetch() function since it does not attempt to
"fetch" an implementation of the cipher. Additionally, it only
knows about digests that are built-in to OpenSSL and have an associated
NID. Similarly EVP_get_digestbynid() and
EVP_get_digestbyobj() also return objects without an associated
implementation.
When the digest objects returned by these functions are used (such as in a
call to EVP_DigestInit_ex()) an implementation of the digest will
be implicitly fetched from the loaded providers. This fetch could fail if
no suitable implementation is available. Use EVP_MD_fetch() instead
to explicitly fetch the algorithm and an associated implementation from a
provider.
See "ALGORITHM FETCHING" in crypto(7) for more information
about fetching.
The digest objects returned from these functions do not need to be freed
with EVP_MD_free().
- EVP_MD_CTX_get_pkey_ctx()
- Returns the EVP_PKEY_CTX assigned to ctx. The
returned pointer should not be freed by the caller.
- EVP_MD_CTX_set_pkey_ctx()
- Assigns an EVP_PKEY_CTX to EVP_MD_CTX. This
is usually used to provide a customized EVP_PKEY_CTX to
EVP_DigestSignInit(3) or EVP_DigestVerifyInit(3). The
pctx passed to this function should be freed by the caller. A NULL
pctx pointer is also allowed to clear the EVP_PKEY_CTX
assigned to ctx. In such case, freeing the cleared
EVP_PKEY_CTX or not depends on how the EVP_PKEY_CTX is
created.
- EVP_MD_do_all_provided()
- Traverses all messages digests implemented by all activated
providers in the given library context libctx, and for each of the
implementations, calls the given function fn with the
implementation method and the given arg as argument.
See
OSSL_PARAM(3) for information about passing parameters.
EVP_MD_CTX_set_params() can be used with the following OSSL_PARAM keys:
- "xoflen" (OSSL_DIGEST_PARAM_XOFLEN)
<unsigned integer>
- Sets the digest length for extendable output functions. It
is used by the SHAKE algorithm and should not exceed what can be given
using a size_t.
- "pad-type" (OSSL_DIGEST_PARAM_PAD_TYPE)
<unsigned integer>
- Sets the padding type. It is used by the MDC2
algorithm.
EVP_MD_CTX_get_params() can be used with the following OSSL_PARAM keys:
- "micalg" (OSSL_PARAM_DIGEST_KEY_MICALG)
<UTF8 string>.
- Gets the digest Message Integrity Check algorithm string.
This is used when creating S/MIME multipart/signed messages, as specified
in RFC 3851. It may be used by external engines or providers.
EVP_MD_CTX_ctrl() can be used to send the following standard controls:
- EVP_MD_CTRL_MICALG
- Gets the digest Message Integrity Check algorithm string.
This is used when creating S/MIME multipart/signed messages, as specified
in RFC 3851. The string value is written to p2.
When used with a fetched EVP_MD, EVP_MD_CTX_get_params() gets
called with an OSSL_PARAM(3) item with the key "micalg"
(OSSL_DIGEST_PARAM_MICALG).
- EVP_MD_CTRL_XOF_LEN
- This control sets the digest length for extendable output
functions to p1. Sending this control directly should not be
necessary, the use of EVP_DigestFinalXOF() is preferred. Currently
used by SHAKE.
When used with a fetched EVP_MD, EVP_MD_CTX_get_params() gets
called with an OSSL_PARAM(3) item with the key "xoflen"
(OSSL_DIGEST_PARAM_XOFLEN).
EVP_MD_CTX_set_flags(),
EVP_MD_CTX_clear_flags() and
EVP_MD_CTX_test_flags() can be used the manipulate and test these
EVP_MD_CTX flags:
- EVP_MD_CTX_FLAG_ONESHOT
- This flag instructs the digest to optimize for one update
only, if possible.
- EVP_MD_CTX_FLAG_NO_INIT
- This flag instructs EVP_DigestInit() and similar not
to initialise the implementation specific data.
- EVP_MD_CTX_FLAG_FINALISE
- Some functions such as EVP_DigestSign only finalise copies
of internal contexts so additional data can be included after the
finalisation call. This is inefficient if this functionality is not
required, and can be disabled with this flag.
- EVP_MD_fetch()
- Returns a pointer to a EVP_MD for success or NULL
for failure.
- EVP_MD_up_ref()
- Returns 1 for success or 0 for failure.
-
EVP_Q_digest(), EVP_Digest(),
EVP_DigestInit_ex2(), EVP_DigestInit_ex(),
EVP_DigestInit(), EVP_DigestUpdate(),
EVP_DigestFinal_ex(), EVP_DigestFinalXOF(), and
EVP_DigestFinal()
- return 1 for success and 0 for failure.
- EVP_MD_CTX_ctrl()
- Returns 1 if successful or 0 for failure.
-
EVP_MD_CTX_set_params(),
EVP_MD_CTX_get_params()
- Returns 1 if successful or 0 for failure.
-
EVP_MD_CTX_settable_params(),
EVP_MD_CTX_gettable_params()
- Return an array of constant OSSL_PARAM(3)s, or NULL
if there is none to get.
- EVP_MD_CTX_copy_ex()
- Returns 1 if successful or 0 for failure.
-
EVP_MD_get_type(),
EVP_MD_get_pkey_type()
- Returns the NID of the corresponding OBJECT IDENTIFIER or
NID_undef if none exists.
-
EVP_MD_get_size(), EVP_MD_get_block_size(),
EVP_MD_CTX_get_size(), EVP_MD_CTX_get_block_size()
- Returns the digest or block size in bytes or -1 for
failure.
- EVP_md_null()
- Returns a pointer to the EVP_MD structure of the
"null" message digest.
-
EVP_get_digestbyname(),
EVP_get_digestbynid(), EVP_get_digestbyobj()
- Returns either an EVP_MD structure or NULL if an
error occurs.
- EVP_MD_CTX_set_pkey_ctx()
- This function has no return value.
- EVP_MD_names_do_all()
- Returns 1 if the callback was called for all names. A
return value of 0 means that the callback was not called for any
names.
The
EVP interface to message digests should almost always be used in
preference to the low-level interfaces. This is because the code then becomes
transparent to the digest used and much more flexible.
New applications should use the SHA-2 (such as
EVP_sha256(3)) or the
SHA-3 digest algorithms (such as
EVP_sha3_512(3)). The other digest
algorithms are still in common use.
For most applications the
impl parameter to
EVP_DigestInit_ex()
will be set to NULL to use the default digest implementation.
Ignoring failure returns of
EVP_DigestInit_ex(),
EVP_DigestInit_ex2(), or
EVP_DigestInit() can lead to undefined
behavior on subsequent calls updating or finalizing the
EVP_MD_CTX such
as the
EVP_DigestUpdate() or
EVP_DigestFinal() functions. The
only valid calls on the
EVP_MD_CTX when initialization fails are calls
that attempt another initialization of the context or release the context.
The functions
EVP_DigestInit(),
EVP_DigestFinal() and
EVP_MD_CTX_copy() are obsolete but are retained to maintain
compatibility with existing code. New applications should use
EVP_DigestInit_ex(),
EVP_DigestFinal_ex() and
EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest
context instead of initializing and cleaning it up on each call and allow non
default implementations of digests to be specified.
If digest contexts are not cleaned up after use, memory leaks will occur.
EVP_MD_CTX_get0_name(),
EVP_MD_CTX_get_size(),
EVP_MD_CTX_get_block_size(),
EVP_MD_CTX_get_type(),
EVP_get_digestbynid() and
EVP_get_digestbyobj() are defined as
macros.
EVP_MD_CTX_ctrl() sends commands to message digests for additional
configuration or control.
This example digests the data "Test Message\n" and "Hello
World\n", using the digest name passed on the command line.
#include <stdio.h>
#include <string.h>
#include <openssl/evp.h>
int main(int argc, char *argv[])
{
EVP_MD_CTX *mdctx;
const EVP_MD *md;
char mess1[] = "Test Message\n";
char mess2[] = "Hello World\n";
unsigned char md_value[EVP_MAX_MD_SIZE];
unsigned int md_len, i;
if (argv[1] == NULL) {
printf("Usage: mdtest digestname\n");
exit(1);
}
md = EVP_get_digestbyname(argv[1]);
if (md == NULL) {
printf("Unknown message digest %s\n", argv[1]);
exit(1);
}
mdctx = EVP_MD_CTX_new();
if (!EVP_DigestInit_ex2(mdctx, md, NULL)) {
printf("Message digest initialization failed.\n");
EVP_MD_CTX_free(mdctx);
exit(1);
}
if (!EVP_DigestUpdate(mdctx, mess1, strlen(mess1))) {
printf("Message digest update failed.\n");
EVP_MD_CTX_free(mdctx);
exit(1);
}
if (!EVP_DigestUpdate(mdctx, mess2, strlen(mess2))) {
printf("Message digest update failed.\n");
EVP_MD_CTX_free(mdctx);
exit(1);
}
if (!EVP_DigestFinal_ex(mdctx, md_value, &md_len)) {
printf("Message digest finalization failed.\n");
EVP_MD_CTX_free(mdctx);
exit(1);
}
EVP_MD_CTX_free(mdctx);
printf("Digest is: ");
for (i = 0; i < md_len; i++)
printf("%02x", md_value[i]);
printf("\n");
exit(0);
}
EVP_MD_meth_new(3),
openssl-dgst(1),
evp(7),
OSSL_PROVIDER(3),
OSSL_PARAM(3),
property(7),
"ALGORITHM FETCHING" in
crypto(7),
provider-digest(7),
life_cycle-digest(7)
The full list of digest algorithms are provided below.
EVP_blake2b512(3),
EVP_md2(3),
EVP_md4(3),
EVP_md5(3),
EVP_mdc2(3),
EVP_ripemd160(3),
EVP_sha1(3),
EVP_sha224(3),
EVP_sha3_224(3),
EVP_sm3(3),
EVP_whirlpool(3)
The
EVP_MD_CTX_create() and
EVP_MD_CTX_destroy() functions were
renamed to
EVP_MD_CTX_new() and
EVP_MD_CTX_free() in OpenSSL
1.1.0, respectively.
The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
later, so now
EVP_sha1() can be used with RSA and DSA.
The
EVP_dss1() function was removed in OpenSSL 1.1.0.
The
EVP_MD_CTX_set_pkey_ctx() function was added in OpenSSL 1.1.1.
The
EVP_Q_digest(),
EVP_DigestInit_ex2(),
EVP_MD_fetch(),
EVP_MD_free(),
EVP_MD_up_ref(),
EVP_MD_get_params(),
EVP_MD_CTX_set_params(),
EVP_MD_CTX_get_params(),
EVP_MD_gettable_params(),
EVP_MD_gettable_ctx_params(),
EVP_MD_settable_ctx_params(),
EVP_MD_CTX_settable_params() and
EVP_MD_CTX_gettable_params() functions were added in OpenSSL 3.0.
The
EVP_MD_type(),
EVP_MD_nid(),
EVP_MD_name(),
EVP_MD_pkey_type(),
EVP_MD_size(),
EVP_MD_block_size(),
EVP_MD_flags(),
EVP_MD_CTX_size(),
EVP_MD_CTX_block_size(),
EVP_MD_CTX_type(), and
EVP_MD_CTX_md_data() functions were renamed to include "get"
or "get0" in their names in OpenSSL 3.0, respectively. The old names
are kept as non-deprecated alias macros.
The
EVP_MD_CTX_md() function was deprecated in OpenSSL 3.0; use
EVP_MD_CTX_get0_md() instead.
EVP_MD_CTX_update_fn() and
EVP_MD_CTX_set_update_fn() were deprecated in OpenSSL 3.0.
Copyright 2000-2023 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>.