'\" t
.\"     Title: zdigest
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 01/17/2021
.\"    Manual: CZMQ Manual
.\"    Source: CZMQ 4.2.1
.\"  Language: English
.\"
.TH "ZDIGEST" "3" "01/17/2021" "CZMQ 4\&.2\&.1" "CZMQ Manual"
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.SH "NAME"
zdigest \- Class for provides hashing functions (SHA\-1 at present)
.SH "SYNOPSIS"
.sp
.nf
//  This is a stable class, and may not change except for emergencies\&. It
//  is provided in stable builds\&.
//  Constructor \- creates new digest object, which you use to build up a
//  digest by repeatedly calling zdigest_update() on chunks of data\&.
CZMQ_EXPORT zdigest_t *
    zdigest_new (void);

//  Destroy a digest object
CZMQ_EXPORT void
    zdigest_destroy (zdigest_t **self_p);

//  Add buffer into digest calculation
CZMQ_EXPORT void
    zdigest_update (zdigest_t *self, const byte *buffer, size_t length);

//  Return final digest hash data\&. If built without crypto support,
//  returns NULL\&.
CZMQ_EXPORT const byte *
    zdigest_data (zdigest_t *self);

//  Return final digest hash size
CZMQ_EXPORT size_t
    zdigest_size (zdigest_t *self);

//  Return digest as printable hex string; caller should not modify nor
//  free this string\&. After calling this, you may not use zdigest_update()
//  on the same digest\&. If built without crypto support, returns NULL\&.
CZMQ_EXPORT char *
    zdigest_string (zdigest_t *self);

//  Self test of this class\&.
CZMQ_EXPORT void
    zdigest_test (bool verbose);

Please add \*(Aq@interface\*(Aq section in \*(Aq\&./\&.\&./src/zdigest\&.c\*(Aq\&.
.fi
.SH "DESCRIPTION"
.sp
The zdigest class generates a hash from zchunks of data\&. The current algorithm is SHA\-1, chosen for speed\&. We are aiming to generate a unique digest for a file, and there are no security issues in this use case\&.
.sp
The current code depends on OpenSSL, which might be replaced by hard coded SHA\-1 implementation to reduce build dependencies\&.
.SH "EXAMPLE"
.PP
\fBFrom zdigest_test method\fR. 
.sp
.if n \{\
.RS 4
.\}
.nf
byte *buffer = (byte *) zmalloc (1024);
memset (buffer, 0xAA, 1024);

zdigest_t *digest = zdigest_new ();
assert (digest);
zdigest_update (digest, buffer, 1024);
const byte *data = zdigest_data (digest);
assert (data [0] == 0xDE);
assert (data [1] == 0xB2);
assert (data [2] == 0x38);
assert (data [3] == 0x07);
assert (streq (zdigest_string (digest),
               "DEB23807D4FE025E900FE9A9C7D8410C3DDE9671"));
zdigest_destroy (&digest);
freen (buffer);

#if defined (__WINDOWS__)
zsys_shutdown();
#endif
.fi
.if n \{\
.RE
.\}
.sp
.SH "AUTHORS"
.sp
The czmq manual was written by the authors in the AUTHORS file\&.
.SH "RESOURCES"
.sp
Main web site: \m[blue]\fB\%\fR\m[]
.sp
Report bugs to the email <\m[blue]\fBzeromq\-dev@lists\&.zeromq\&.org\fR\m[]\&\s-2\u[1]\d\s+2>
.SH "COPYRIGHT"
.sp
Copyright (c) the Contributors as noted in the AUTHORS file\&. This file is part of CZMQ, the high\-level C binding for 0MQ: http://czmq\&.zeromq\&.org\&. This Source Code Form is subject to the terms of the Mozilla Public License, v\&. 2\&.0\&. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla\&.org/MPL/2\&.0/\&. LICENSE included with the czmq distribution\&.
.SH "NOTES"
.IP " 1." 4
zeromq-dev@lists.zeromq.org
.RS 4
\%mailto:zeromq-dev@lists.zeromq.org
.RE