dacs_token — manage DACS one-time password token accounts


dacs_token [dacsoptions]


This program is part of the DACS suite.

The dacs_token web service provides limited account management operations on accounts recognized by local_token_authenticate, a DACS authentication module. Full administrative functionality is provided by dacstoken; refer to dacstoken(1) for detailed information about one-time passwords, token devices, and user accounts. These accounts are completely separate from any other accounts and passwords.

Subject to configuration and valid authorization, this web service lets:

  • users set an initial PIN for their account (note that his presents a window of opportunity for an attacker that has obtained a PIN-less token);

  • users change the PIN on their account;

  • users synchronize their account with their token; and

  • DACS administrators (see ADMIN_IDENTITY) set, change, or remove the PIN on any account, synchronize an account with a token (removal depends on TOKEN_REQUIRES_PIN), or obtain the next OTP for a specified account;

  • anyone create and test a demonstration account (visit dacs.dss.ca to try a live demonstration).

Outside of demonstration mode operation, accounts are managed identically to dacstoken(1) using the item types auth_token, auth_hotp_token, and auth_totp_token.


The same account security stipulations as dacstoken apply.

The web service applies access controls internally; a DACS ACL can be added to further restrict its use. The internal rules are:

  • A DACS administrator can synchronize any account without providing the account's PIN; other users must provide the account's PIN, if there is one.

  • A DACS administrator can set, change, or remove (depending on TOKEN_REQUIRES_PIN) any account's PIN; other users can set or change their account's PIN by:

    • authenticating as the username of the account being accessed (if the account has a PIN and the user has forgotten it, presumably a different authentication method must be used); or

    • contacting a DACS administrator.

  • Demonstration mode is enabled if the item type auth_token_demo is defined; otherwise, if auth_token_hotp_demo is defined, then demonstration mode for HOTP is enabled, and if auth_token_totp_demo is defined, then demonstration mode for TOTP is enabled. If none of these item types is enabled, which is the default, then demonstration mode is inoperative.

When validating a HOTP one-time password, the TOKEN_HOTP_ACCEPT_WINDOW configuration directive can be used to allow an account's counter value to automatically "catch up" to the token's.


Web Service Arguments

In addition to the standard CGI arguments, dacs_token understands the following CGI arguments:


Required with the SET_PIN operation, the value of this argument must be the same as the value of CONFIRM_NEW_PIN.


The following operations are supported:


    Unlike the other operations, this operation returns a text/plain MIME type, consisting of the current moving factor (i.e., the HOTP counter value or the TOTP interval value), followed by a space and the corresponding OTP for USERNAME. This facilitates an easy-to-use, REST-type interface. In the case of HOTP, the counter value is advanced, "consuming" the OTP. Only an administrator is allowed to perform this operation, which can be used to build a simple mutual authentication capability:

    1. The user gives a username to the sign-on procedure;

    2. The sign-on procedure asks DACS for the OTP it expects the user's token to produce, based on the user's account parameters;

    3. The sign-on procedure presents the OTP to the user, who verifies its correctness by matching the presented OTP with the one actually produced by the token;

    4. The user continues the authentication procedure, perhaps by providing the token's next OTP or using another authentication method, such as a password.

    The appropriateness of TOTP mode for mutual authentication depends on the OTP lifetime and other configuration parameters.


    Set or change the PIN associated with the account for USERNAME. This operation requires the NEW_PIN, CONFIRM_NEW_PIN, MODE, and USERNAME arguments.

  • SYNC

    Synchronize the account for USERNAME so that the next password produced by the token is expected to be valid. This operation requires the PASSWORD, MODE, and USERNAME arguments.


    Create a demonstration account according to the given arguments, configuration values, and defaults. Required arguments: MODE, KEY, KEY_ENCODING. Optional arguments: NEW_PIN, CONFIRM_NEW_PIN, NDIGITS, BASE, SERIAL. Optional HOTP argument: COUNTER. Optional TOTP arguments: DIGEST_NAME, TIME_STEP. The KEY_ENCODING argument, which indicates how the KEY string has been encoded, must be one of hex, base32, or none.


    Synchronize a demonstration account using USERNAME, a one-time password or password sequence (SYNC), and optional PIN.


    Validate the given demonstration account (USERNAME), one-time password (PASSWORD), and PIN (PIN) in demonstration mode. No credentials are actually issued.


This argument is the device mode, which may be (case insensitively) counter or hotp for counter mode, or time or totp for time-based mode.


With the SET_PIN operation, this is the new PIN to associate with the account. An administrator can remove the PIN entirely, provided it is allowed by TOKEN_REQUIRES_PIN, by omitting (or not providing a value for) both NEW_PIN and CONFIRM_NEW_PIN.


If the request is not accompanied by credentials for USERNAME or an administrator identity, this one-time password must validate against the expected value for USERNAME.



The DACS username of interest.


The program exits 0 if everything was fine, 1 if an error occurred.


This version only provides self-service operations for users and limited account management for a DACS administrator; administrators must use dacstoken(1) for everything else. Full-blown web-based token account management should either be provided by dacs_token or dacs_admin(8).

Demonstration mode accounts should be manually deleted from time to time.

The FORMAT is not understood. XML responses should be implemented.


dacstoken(1), dacs.conf(5), dacs_authenticate(8). Also see the OTP token demonstration, token_demo.html.


Distributed Systems Software (www.dss.ca)


Copyright 2003-2018 Distributed Systems Software. See the LICENSE file that accompanies the distribution for licensing information.

DACS Version 1.4.51 20-Jun-2024 DACS_TOKEN(8)

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