Daisuke Takahashi

<p>This plugin adds SMS support to <a href="https://wordpress.org/plugins/two-factor/" rel="ugc">Two Factor</a> with Twilio.</p>
<h3>Notice</h3>
<ul>
<li><strong>Important</strong>: To use this plugin, check following.
<ol>
<li>Installed and activated the latest version of <a href="https://wordpress.org/plugins/two-factor/" rel="ugc">Two Factor</a></li>
<li>Twilio account and Twilio number which supports SMS. For details, please contact Twilio support.</li>
</ol>
</li>
</ul>
<h3>License</h3>
<ul>
<li>Copyright (c) 2012-2014 <a href="http://www.extendwings.com/" rel="nofollow ugc">Daisuke Takahashi(Extend Wings)</a></li>
<li>Portions (c) 2010-2012 Web Online.</li>
<li>Unless otherwise stated, all files in this repo is licensed under <em>GNU AFFERO GENERAL PUBLIC LICENSE, Version 3</em>. See <em>LICENSE</em> file.</li>
</ul>
<h4>The MIT License</h4>
<ul>
<li>includes/Twilio/
<ul>
<li>Copyright (c) 2011 Twilio, Inc. and Neuman Vong</li>
<li>Licensed under <a href="https://raw.githubusercontent.com/twilio/twilio-php/9b83e2f1c480e3fb4e05a833b325c5afa43520fb/LICENSE" rel="nofollow ugc">the MIT License</a></li>
<li>Fetched from <a href="https://github.com/twilio/twilio-php/" rel="nofollow ugc">twilio/twilio-php</a></li>
<li>Version: 4.3.0</li>
</ul>
</li>
</ul>


Two Factor SMS

Add SMS support to "Two Factor" feature as a plugin

rishav001

<p>Rishav AuthNova OTP adds a one-time-password verification layer to core WordPress authentication flows.</p>
<p>Features include:</p>
<ul>
<li>Configurable OTP length and charset (numeric or alphanumeric)</li>
<li>OTP expiry and retry limits with temporary lockouts</li>
<li>Login OTP verification step (after password check)</li>
<li>OTP-gated registration flow</li>
<li>OTP-gated password reset flow</li>
<li>Delivery via wp_mail, SendGrid, and Twilio</li>
<li>OTP storage using hashes (never plaintext)</li>
<li>Resend OTP with cooldown and challenge rotation</li>
</ul>
<p>Security highlights:</p>
<ul>
<li>OTP values are hashed before storage and are never saved as plaintext</li>
<li>OTP hashes use keyed HMAC storage and constant-time verification</li>
<li>OTP challenges expire automatically and enforce retry limits per challenge</li>
<li>Request throttling applies cooldown and exponential backoff per IP and identifier</li>
<li>Lockout windows reduce repeated invalid OTP submissions</li>
<li>Nonces are applied on sensitive form submissions</li>
<li>Public auth responses are intentionally generic to reduce account-enumeration leakage</li>
<li>Delivery uses synchronous-first send with bounded async retry fallback and challenge-level delivery status tracking</li>
</ul>
<p>Security limitations:</p>
<ul>
<li>This plugin does not replace passwords, HTTPS, WAF/rate-limiting at the edge, or secure hosting controls</li>
<li>OTP delivery depends on the configured email/SMS provider uptime and deliverability</li>
<li>Administrators should combine this plugin with standard WordPress hardening and monitoring</li>
</ul>
<p>Reliability notes:</p>
<ul>
<li>OTP delivery is attempted synchronously first to reduce silent failures</li>
<li>If synchronous delivery fails and background delivery is healthy, the plugin schedules bounded retries</li>
<li>If background delivery is unhealthy (for example DISABLE_WP_CRON), fallback queueing is skipped and users receive a retry-safe error</li>
<li>Resend cooldown state is server-authoritative and exposed through a status endpoint used by frontend countdown UX</li>
<li>Background queue payload contains only challenge ID (no raw OTP or destination data)</li>
</ul>
<h3>External Services</h3>
<p>This plugin can connect to third-party services to deliver OTP messages. These services are optional and only used if enabled in plugin settings.</p>
<h4>Twilio (SMS Delivery)</h4>
<ul>
<li>Service: Twilio Programmable Messaging API</li>
<li>Purpose: Send OTP codes by SMS</li>
<li>Data sent: destination phone number, sender phone number, OTP message text, account SID for authentication</li>
<li>Credential handling: Twilio credentials are stored in WordPress options and used only when sending OTP messages</li>
<li>When sent: when OTP delivery method includes SMS and an OTP is generated for login, registration, password reset, or resend</li>
<li>Why sent: to deliver time-sensitive OTP codes to the user by SMS</li>
<li>Terms of Service: https://www.twilio.com/legal/tos</li>
<li>Privacy Policy: https://www.twilio.com/en-us/legal/privacy</li>
</ul>
<h4>SendGrid (Email Delivery)</h4>
<ul>
<li>Service: SendGrid Mail Send API</li>
<li>Purpose: Send OTP codes by email</li>
<li>Data sent: recipient email address, sender email/name, message subject, OTP message body, API key for authentication</li>
<li>Credential handling: SendGrid API key is stored in WordPress options and used only when sending OTP messages</li>
<li>When sent: when email provider is set to SendGrid and an OTP is generated for login, registration, password reset, or resend</li>
<li>Why sent: to deliver time-sensitive OTP codes to the user by email</li>
<li>Terms of Service: https://sendgrid.com/policies/terms/</li>
<li>Privacy Policy: https://sendgrid.com/policies/privacy/</li>
</ul>
<h3>Configuration</h3>
<ol>
<li>Set OTP length, type, expiry, retry limit, and lockout duration.</li>
<li>Choose delivery method: Email, SMS, or Both.</li>
<li>Configure provider credentials for SendGrid and/or Twilio if needed.</li>
<li>Enable or disable OTP on login, registration, and password reset flows.</li>
</ol>


Rishav AuthNova OTP

OTP verification for WordPress login, registration, and password reset using email and SMS delivery.

Two Factor SMS vs Rishav AuthNova OTP