Pass::OTP - Perl implementation of HOTP / TOTP algorithms

       Copyright (C) 2020 Jan Baier

       This  program  is  free software; you can redistribute it and/or modify it under the terms of either: the
       GNU General Public License as published by the Free Software Foundation; or the Artistic License.

       See <http://dev.perl.org/licenses/> for more information.

perl v5.40.0                                       2025-01-26                                     Pass::OTP(3pm)

       The "Pass::OTP" module provides implementation of HOTP and TOTP algorithms according to the RFC 4226 and
       RFC 6238.

       hotp(%options)
           Computes HMAC-based One-time Password (RFC 4226).

               HOTP(K,C) = Truncate(HMAC-SHA-1(K,C))

           Step 1: Generate an HMAC-SHA-1 value

               Let HS = HMAC-SHA-1(K,C)

           Step 2: Generate a 4-byte string (Dynamic Truncation)

               Let Sbits = DT(HS)

           Step 3: Compute an HOTP value

               Let Snum = StToNum(Sbits)       # Convert S to a number in 0..2^{31}-1
               Return D = Snum mod 10^Digit    # D us a number in the range 0..10^{Digit}-1

       totp(%options)
           Computes Time-based One-time Password (RFC 6238).

               TOTP = HOTP(K,T)
               T = (Current Unix time - T0) / X

       otp(%options)
           Convenience wrapper which calls totp/hotp according to options.

       Pass::OTP - Perl implementation of HOTP / TOTP algorithms

       Digest::HMAC

       oathtool(1)

       RFC 4226 RFC 6238

       <https://github.com/google/google-authenticator/wiki/Key-Uri-Format>

           use Pass::OTP qw(otp);
           use Pass::OTP::URI qw(parse);

           my $uri = "otpauth://totp/ACME:john.doe@email.com?secret=HXDMVJECJJWSRB3HWIZR4IFUGFTMXBOZ&issuer=ACME&digits=6";
           my $otp_code = otp(parse($uri));