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zdigest - Class for provides hashing functions (SHA-1 at present)


//  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 '@interface' section in './../src/zdigest.c'.


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.

The current code depends on OpenSSL, which might be replaced by hard coded SHA-1 implementation to reduce build dependencies.


From zdigest_test method.

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


The czmq manual was written by the authors in the AUTHORS file.


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Copyright (c) the Contributors as noted in the AUTHORS file. This file is part of CZMQ, the high-level C binding for 0MQ: 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 LICENSE included with the czmq distribution.


01/17/2021 CZMQ 4.2.1