.\" -*- mode: troff; coding: utf-8 -*-
.\" Automatically generated by Pod::Man v6.0.2 (Pod::Simple 3.48)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>.
.ie n \{\
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds C`
.    ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is >0, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{\
.    if \nF \{\
.        de IX
.        tm Index:\\$1\t\\n%\t"\\$2"
..
.        if !\nF==2 \{\
.            nr % 0
.            nr F 2
.        \}
.    \}
.\}
.rr rF
.\"
.\" Required to disable full justification in groff 1.23.0.
.if n .ds AD l
.\" ========================================================================
.\"
.IX Title "EVP_MD-COMMON 7ossl"
.TH EVP_MD-COMMON 7ossl 2026-09-29 4.0.3 OpenSSL
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
EVP_MD\-common \- The OpenSSL EVP_MD implementations, common things
.SH DESCRIPTION
.IX Header "DESCRIPTION"
All the OpenSSL EVP_MD implementations understand the following
\&\fBOSSL_PARAM\fR\|(3) entries that are
gettable with \fBEVP_MD_get_params\fR\|(3), as well as these:
.IP """blocksize"" (\fBOSSL_DIGEST_PARAM_BLOCK_SIZE\fR) <unsigned integer>" 4
.IX Item """blocksize"" (OSSL_DIGEST_PARAM_BLOCK_SIZE) <unsigned integer>"
The digest block size.
The length of the "blocksize" parameter should not exceed that of a
\&\fBsize_t\fR.
.Sp
This value can also be retrieved with \fBEVP_MD_get_block_size\fR\|(3).
.IP """size"" (\fBOSSL_DIGEST_PARAM_SIZE\fR) <unsigned integer>" 4
.IX Item """size"" (OSSL_DIGEST_PARAM_SIZE) <unsigned integer>"
The digest output size.
The length of the "size" parameter should not exceed that of a \fBsize_t\fR.
.Sp
This value can also be retrieved with \fBEVP_MD_get_size\fR\|(3).
.IP """flags"" (\fBOSSL_DIGEST_PARAM_FLAGS\fR) <unsigned integer>" 4
.IX Item """flags"" (OSSL_DIGEST_PARAM_FLAGS) <unsigned integer>"
Diverse flags that describe exceptional behaviour for the digest.
.Sp
The length of the "flags" parameter should equal that of an
\&\fBunsigned long int\fR.
.Sp
Several flags can be or\*(Aqd together.  The available flags are:
.RS 4
.IP EVP_MD_FLAG_ONESHOT 4
.IX Item "EVP_MD_FLAG_ONESHOT"
This digest method can only handle one block of input.
.IP EVP_MD_FLAG_XOF 4
.IX Item "EVP_MD_FLAG_XOF"
This digest method is an extensible\-output function (XOF) and supports
the \fBEVP_MD_CTRL_XOF_LEN\fR control.
.IP EVP_MD_FLAG_DIGALGID_NULL 4
.IX Item "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.  \fINote: if
combined with EVP_MD_FLAG_DIGALGID_ABSENT, the latter will override.\fR
.IP EVP_MD_FLAG_DIGALGID_ABSENT 4
.IX Item "EVP_MD_FLAG_DIGALGID_ABSENT"
When setting up a DigestAlgorithmIdentifier, this flag will have the
parameter be left absent by default.  \fINote: if combined with
EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.\fR
.IP EVP_MD_FLAG_DIGALGID_CUSTOM 4
.IX Item "EVP_MD_FLAG_DIGALGID_CUSTOM"
Custom DigestAlgorithmIdentifier handling via ctrl, with
\&\fBEVP_MD_FLAG_DIGALGID_ABSENT\fR as default.  \fINote: if combined with
EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.\fR
Currently unused.
.IP EVP_MD_FLAG_FIPS 4
.IX Item "EVP_MD_FLAG_FIPS"
This digest method is suitable for use in FIPS mode.
Currently unused.
.RE
.RS 4
.Sp
This value can also be retrieved with \fBEVP_MD_get_flags\fR\|(3).
.RE
.SS "FIPS indicator"
.IX Subsection "FIPS indicator"
Digest implementations in the OpenSSL FIPS provider make the following
parameter available with \fBEVP_MD_CTX_get_params\fR\|(3):
.IP """fips\-indicator"" (\fBOSSL_DIGEST_PARAM_FIPS_APPROVED_INDICATOR\fR) <integer>" 4
.IX Item """fips-indicator"" (OSSL_DIGEST_PARAM_FIPS_APPROVED_INDICATOR) <integer>"
Returns 1 if the operation is FIPS approved, or 0 otherwise.
See "FIPS indicators" in \fBfips_module\fR\|(7) for more information.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
"PARAMETERS" in \fBEVP_DigestInit\fR\|(3), \fBEVP_MD_get_params\fR\|(3), \fBprovider\-digest\fR\|(7)
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2020\-2026 The OpenSSL Project Authors. All Rights Reserved.
.PP
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>.