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digest_file_auth(8) System Manager's Manual digest_file_auth(8)


digest_file_auth - File based digest authentication helper for Squid.

Version 1.1


digest_file_auth [-c] file


digest_file_auth is an installed binary authentication program for Squid. It handles digest authentication protocol and authenticates against a text file backend. This program will automatically detect the existence of a concurrency channel-ID and adjust appropriately. It may be used with any value 0 or above for the auth_param children concurrency= parameter.


Accept digest hashed passwords rather than plaintext in the password file


Username database file format:

To build a directory integrated backend, you need to be able to calculate the HA1 returned to squid. To avoid storing a plaintext password you can calculate MD5(username:realm:password) when the user changes their password, and store the tuple username:realm:HA1. then find the matching username:realm when squid asks for the HA1.

This implementation could be improved by using such a triple for the file format. However storing such a triple does little to improve security: If compromised the username:realm:HA1 combination is "plaintext equivalent" - for the purposes of digest authentication they allow the user access. Password synchronization is not tackled by digest - just preventing on the wire compromise.


This program was written by Robert Collins <>

Based on prior work by Arjan de Vet <>

This manual was written by Robert Collins <> Amos Jeffries <>


* Copyright (C) 1996-2018 The Squid Software Foundation and contributors
* Squid software is distributed under GPLv2+ license and includes
* contributions from numerous individuals and organizations.
* Please see the COPYING and CONTRIBUTORS files for details.

This program and documentation is copyright to the authors named above.

Distributed under the GNU General Public License (GNU GPL) version 2 or later (GPLv2+).


Questions on the usage of this program can be sent to the Squid Users mailing list <>


Bug reports need to be made in English. See for details of what you need to include with your bug report.

Report bugs or bug fixes using

Report serious security bugs to Squid Bugs <>

Report ideas for new improvements to the Squid Developers mailing list <>


squid(8), GPL(7),
The Squid FAQ wiki
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