path: root/src/lib/libcrypto/man/EVP_MD_meth_new.3

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.Dd $Mdocdate: September 12 2023 $
.Dt EVP_MD_METH_NEW 3
.Os
.Sh NAME
.Nm EVP_MD_meth_dup ,
.Nm EVP_MD_meth_new ,
.Nm EVP_MD_meth_free ,
.Nm EVP_MD_meth_set_input_blocksize ,
.Nm EVP_MD_meth_set_result_size ,
.Nm EVP_MD_meth_set_app_datasize ,
.Nm EVP_MD_meth_set_flags ,
.Nm EVP_MD_meth_set_init ,
.Nm EVP_MD_meth_set_update ,
.Nm EVP_MD_meth_set_final ,
.Nm EVP_MD_meth_set_copy ,
.Nm EVP_MD_meth_set_cleanup ,
.Nm EVP_MD_meth_set_ctrl
.Nd Routines to build up EVP_MD methods
.Sh SYNOPSIS
.In openssl/evp.h
.Ft EVP_MD *
.Fo EVP_MD_meth_new
.Fa "int md_type"
.Fa "int pkey_type"
.Fc
.Ft void
.Fo EVP_MD_meth_free
.Fa "EVP_MD *md"
.Fc
.Ft EVP_MD *
.Fo EVP_MD_meth_dup
.Fa "const EVP_MD *md"
.Fc
.Ft int
.Fo EVP_MD_meth_set_input_blocksize
.Fa "EVP_MD *md"
.Fa "int blocksize"
.Fc
.Ft int
.Fo EVP_MD_meth_set_result_size
.Fa "EVP_MD *md"
.Fa "int resultsize"
.Fc
.Ft int
.Fo EVP_MD_meth_set_app_datasize
.Fa "EVP_MD *md"
.Fa "int datasize"
.Fc
.Ft int
.Fo EVP_MD_meth_set_flags
.Fa "EVP_MD *md"
.Fa "unsigned long flags"
.Fc
.Ft int
.Fo EVP_MD_meth_set_init
.Fa "EVP_MD *md"
.Fa "int (*init)(EVP_MD_CTX *ctx)"
.Fc
.Ft int
.Fo EVP_MD_meth_set_update
.Fa "EVP_MD *md"
.Fa "int (*update)(EVP_MD_CTX *ctx, const void *data, size_t count)"
.Fc
.Ft int
.Fo EVP_MD_meth_set_final
.Fa "EVP_MD *md"
.Fa "int (*final)(EVP_MD_CTX *ctx, unsigned char *md)"
.Fc
.Ft int
.Fo EVP_MD_meth_set_copy
.Fa "EVP_MD *md"
.Fa "int (*copy)(EVP_MD_CTX *to, const EVP_MD_CTX *from)"
.Fc
.Ft int
.Fo EVP_MD_meth_set_cleanup
.Fa "EVP_MD *md"
.Fa "int (*cleanup)(EVP_MD_CTX *ctx)"
.Fc
.Ft int
.Fo EVP_MD_meth_set_ctrl
.Fa "EVP_MD *md"
.Fa "int (*control)(EVP_MD_CTX *ctx, int command, int p1, void *p2)"
.Fc
.Sh DESCRIPTION
The
.Vt EVP_MD
type is a structure for digest method implementation.
It can also have associated public/private key signing and verifying
routines.
.Pp
.Fn EVP_MD_meth_new
creates a new
.Vt EVP_MD
structure.
.Pp
.Fn EVP_MD_meth_dup
creates a copy of
.Fa md .
.Pp
.Fn EVP_MD_meth_free
destroys a
.Vt EVP_MD
structure.
.Pp
.Fn EVP_MD_meth_set_input_blocksize
sets the internal input block size for the method
.Fa md
to
.Fa blocksize
bytes.
.Pp
.Fn EVP_MD_meth_set_result_size
sets the size of the result that the digest method in
.Fa md
is expected to produce to
.Fa resultsize
bytes.
.Pp
The digest method may have its own private data, which OpenSSL will
allocate for it.
.Fn EVP_MD_meth_set_app_datasize
should be used to set the size for it to
.Fa datasize .
.Pp
.Fn EVP_MD_meth_set_flags
sets the flags to describe optional behaviours in the particular
.Fa md .
Several flags can be or'd together.
The available flags are:
.Bl -tag -width Ds
.It Dv EVP_MD_FLAG_DIGALGID_NULL
When setting up a
.Vt DigestAlgorithmIdentifier
with
.Xr X509_ALGOR_set_md 3 ,
set the parameter type to
.Dv V_ASN1_NULL
and the parameter value to
.Dv NULL .
This is the default, which means that it takes effect for
.Vt EVP_MD
objects that do not have
.Dv EVP_MD_FLAG_DIGALGID_ABSENT
set.
Use this for PKCS#1.
.It Dv EVP_MD_FLAG_DIGALGID_ABSENT
When setting up a
.Vt DigestAlgorithmIdentifier
with
.Xr X509_ALGOR_set_md 3 ,
set the parameter type to
.Dv V_ASN1_UNDEF
and the parameter value to
.Dv NULL .
This is used by the
.Vt EVP_MD
objects documented in the manual page
.Xr EVP_sha3_224 3
and by the objects returned from
.Xr EVP_sha512 3 ,
.Xr EVP_sha512_256 3 ,
.Xr EVP_sha512_224 3 ,
.Xr EVP_sha384 3 ,
.Xr EVP_sha256 3 ,
.Xr EVP_sha224 3 ,
.Xr EVP_sha1 3 ,
and
.Xr EVP_sm3 3 .
.It Dv EVP_MD_FLAG_DIGALGID_CUSTOM
This flag is reserved for user-defined
.Vt EVP_MD
objects supporting custom
.Vt DigestAlgorithmIdentifier
handling via
.Xr EVP_MD_CTX_ctrl 3 ,
but actually, it is ignored by both LibreSSL and OpenSSL
and such user-defined behaviour is not supported by the libraries.
.It Dv EVP_MD_FLAG_FIPS
Mark the digest method as suitable for FIPS mode.
This flag is ignored by both LibreSSL and OpenSSL.
.It Dv EVP_MD_FLAG_ONESHOT
Intended to indicate that the digest method can only handle one block
of input, but actually, this flag is ignored by both LibreSSL and OpenSSL.
.El
.Pp
.Fn EVP_MD_meth_set_init
sets the digest init function for
.Fa md .
The digest init function is called by
.Xr EVP_Digest 3 ,
.Xr EVP_DigestInit 3 ,
.Xr EVP_DigestInit_ex 3 ,
EVP_SignInit,
.Xr EVP_SignInit_ex 3 ,
.Xr EVP_VerifyInit 3
and
.Xr EVP_VerifyInit_ex 3 .
.Pp
.Fn EVP_MD_meth_set_update
sets the digest update function for
.Fa md .
The digest update function is called by
.Xr EVP_Digest 3 ,
.Xr EVP_DigestUpdate 3
and
.Xr EVP_SignUpdate 3 .
.Pp
.Fn EVP_MD_meth_set_final
sets the digest final function for
.Fa md .
The digest final function is called by
.Xr EVP_Digest 3 ,
.Xr EVP_DigestFinal 3 ,
.Xr EVP_DigestFinal_ex 3 ,
.Xr EVP_SignFinal 3
and
.Xr EVP_VerifyFinal 3 .
.Pp
.Fn EVP_MD_meth_set_copy
sets the function for
.Fa md
to do extra computations after the method's private data structure has
been copied from one
.Vt EVP_MD_CTX
object to another.
If all that's needed is to copy the data, there is no need for this copy
function.
The copy function is passed two
.Vt EVP_MD_CTX
objects, the private data structure is then available with
.Xr EVP_MD_CTX_md_data 3 .
This copy function is called by
.Xr EVP_MD_CTX_copy 3
and
.Xr EVP_MD_CTX_copy_ex 3 .
.Pp
.Fn EVP_MD_meth_set_cleanup
sets the function for
.Fa md
to do extra cleanup before the method's private data structure is
cleaned out and freed.
The cleanup function is passed an
.Vt EVP_MD_CTX
object, the private data structure is then available with
.Xr EVP_MD_CTX_md_data 3 .
This cleanup function is called by
.Xr EVP_MD_CTX_reset 3
and
.Xr EVP_MD_CTX_free 3 .
.Pp
.Fn EVP_MD_meth_set_ctrl
sets the
.Fa control
function for
.Fa md .
The
.Fa control
function supplied by the application program has to return 1 to indicate
success, 0 to indicate failure, or \-1 if the
.Fa command
is not supported for this digest method.
See
.Xr EVP_MD_CTX_ctrl 3
for the available
.Fa command
arguments.
.Sh RETURN VALUES
.Fn EVP_MD_meth_new
and
.Fn EVP_MD_meth_dup
return a pointer to a newly created
.Vt EVP_MD ,
or NULL on failure.
All
.Fn EVP_MD_meth_set_*
functions return 1.
.Sh SEE ALSO
.Xr EVP_DigestInit 3 ,
.Xr EVP_SignInit 3 ,
.Xr EVP_VerifyInit 3
.Sh HISTORY
All these functions
first appeared in OpenSSL 1.1.0 and have been available since
.Ox 7.1 .