slapo-otp(5) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION | SEE ALSO | ACKNOWLEDGEMENT | COLOPHON

SLAPO_OTP(5)               File Formats Manual              SLAPO_OTP(5)

NAME         top

       slapo-otp - OATH One-Time Password module

SYNOPSIS         top

       moduleload otp.la

DESCRIPTION         top

       The otp module allows time-based one-time password, AKA
       "authenticator-style", and HMAC-based one-time password
       authentication to be used in conjunction with a standard LDAP
       password for two-factor authentication.

       With this module, users would use their password, followed with
       the one-time password in the password prompt to authenticate.

       The password needed for a user to authenticate is calculated
       based on a counter (current time in case of TOTP) and a key that
       is referenced in the user's LDAP entry. Since the password is
       based on the time or number of uses, it changes periodically.
       Once used, it cannot be used again so keyloggers and shoulder-
       surfers are thwarted. A mobile phone application, such as the
       Google Authenticator or YubiKey (a prover), can be used to
       calculate the user's current one-time password, which is
       expressed as a (usually six-digit) number.

       Alternatively, the value can be calculated by some other
       application with access to the user's key and delivered to the
       user through SMS or some other channel. When prompted to
       authenticate, the user merely appends the code provided by the
       prover at the end of their password when authenticating.

       This implementation complies with RFC 4226 HOTP HMAC-Based One
       Time Passwords and RFC 6238 TOTP Time-based One Time Passwords
       and includes support for the SHA-1, SHA-256, and SHA-512 HMAC
       algorithms.

       The HMAC key used in the OTP computation is stored in the
       oathOTPToken entry referenced in the user's LDAP entry and the
       parameters are stored in the oathOTPParams LDAP entry referenced
       in the token.

CONFIGURATION         top

       Once the module is configured on the database, it will intercept
       LDAP simple binds for users whose LDAP entry has any of the
       oathOTPUser derived objectlasses attached to it. The attributes
       linking the user and the shared secret are:

              oathTOTPToken: <dn>
                     Mandatory for oathTOTPUser, indicates that the
                     named entry is designated to hold the time-based
                     one-time password shared secret and the last
                     password used.

              oathHOTPToken: <dn>
                     Mandatory for oathHOTPUser, indicates that the
                     named entry is designated to hold the one-time
                     password shared secret and the last password used.

              oathTOTPParams: <dn>
                     Mandatory for oathTOTPToken, indicates that the
                     named entry is designated to hold the parameters to
                     generate time-based one-time password shared
                     secret: its length and algorithm to use as well as
                     the length of each time step and the grace period.

              oathHOTPParams: <dn>
                     Mandatory for oathHOTPToken, indicates that the
                     named entry is designated to hold the parameters to
                     generate one-time password shared secret: its
                     length and algorithm to use as well as the
                     permitted number of passwords to skip.

       The following parts of the OATH-LDAP schema are implemented.

       General attributes:

              oathSecret: <data>
                     The shared secret is stored here as raw bytes.

              oathOTPLength: <length>
                     The password length, usually 6.

              oathHMACAlgorithm: <OID>
                     The OID of the hash algorithm to use as defined in
                     RFC 8018.  Supported algorithms include SHA1,
                     SHA224, SHA256, SHA384 and SHA512.

       The HOTP attributes:

              oathHOTPLookAhead: <number>
                     The number of successive HOTP tokens that can be
                     skipped.

              oathHOTPCounter: <number>
                     The order of the last HOTP token successfully
                     redeemed by the user.

       The TOTP attributes:

              oathTOTPTimeStepPeriod: <seconds>
                     The length of the time-step period for TOTP
                     calculation.

              oathTOTPLastTimeStep: <number>
                     The order of the last TOTP token successfully
                     redeemed by the user.

              oathTOTPTimeStepWindow: <number>
                     The number of time periods around the current time
                     to try when checking the password provided by the
                     user.

              oathTOTPTimeStepDrift: <number>
                     If the client didn't provide the correct token but
                     it still fit with oathTOTPTimeStepWindow above,
                     this attribute records the current offset to
                     provide for slow clock drift of the client device.

SEE ALSO         top

       slapd-config(5).

ACKNOWLEDGEMENT         top

       This work was developed by Ondřej Kuzník and Howard Chu of Symas
       Corporation for inclusion in OpenLDAP Software.

       This work reuses the OATH-LDAP schema developed by Michael
       Ströder.

COLOPHON         top

       This page is part of the OpenLDAP (an open source implementation
       of the Lightweight Directory Access Protocol) project.
       Information about the project can be found at 
       ⟨http://www.openldap.org/⟩.  If you have a bug report for this
       manual page, see ⟨http://www.openldap.org/its/⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨https://git.openldap.org/openldap/openldap.git⟩ on 2021-08-27.
       (At that time, the date of the most recent commit that was found
       in the repository was 2021-08-26.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

SLAPO-OTP                       2018/6/29                   SLAPO_OTP(5)