Mayuresh Full stack developer working on Ruby on Rails and React

Ruby on Rails: Understanding the ROTP Gem

Ruby on Rails: Understanding the ROTP Gem

In the Ruby on Rails framework, developers can leverage the power of the ROTP gem to easily implement OTP functionality.

What is the ROTP Gem?

ROTP, which stands for Ruby One-Time Password, is a gem that provides a simple and straightforward way to generate and validate one-time passwords in Ruby applications. It follows the Time-Based One-Time Password (TOTP) algorithm specified in RFC 6238 and the HMAC-Based One-Time Password (HOTP) algorithm specified in RFC 4226.

The ROTP gem offers a wide range of features, including generating OTPs, verifying OTPs, and managing shared secrets for OTP generation. It also supports multiple hashing algorithms, such as SHA1, SHA256, and SHA512, allowing developers to choose the level of security that suits their needs.

Getting Started

To start using the ROTP gem in your Ruby on Rails application, you need to include it as a dependency in your Gemfile:

gem 'rotp'

After adding the gem, run the bundle command to install it:

bundle install

Now that the ROTP gem is installed, you can begin utilizing its features in your application.

Generating OTPs

To generate an OTP using the ROTP gem, you first need to create a new instance of the ROTP::TOTP class. This class represents a Time-Based One-Time Password generator.

totp ='your_secret_key')

The 'your_secret_key' is the shared secret key used to generate the OTPs. It is important to keep this key secure and confidential.

Once you have the totp object, you can generate an OTP by calling the now method:

otp =

The now method returns the OTP based on the current time. You can also pass a specific time to generate an OTP for that particular moment.

Verifying OTPs

To verify whether an OTP is valid or not, you can use the verify method of the ROTP::TOTP class. It takes the OTP as a parameter and returns true if the OTP is valid and false otherwise.

valid = totp.verify('user_provided_otp')

In the example above, 'user_provided_otp' represents the OTP entered by the user during the authentication process. The valid variable will be true if the OTP is correct and false otherwise.

Customizing OTP Configuration

The ROTP gem provides several options to customize the OTP generation and verification process. For example, you can change the number of digits in the OTP, the time interval, and the hashing algorithm used.

Here’s an example of customizing the number of digits to 6 and the time interval to 30 seconds:

totp ='your_secret_key', digits: 6, interval: 30)

By default, the ROTP gem uses the SHA1 hashing algorithm. If you prefer a stronger algorithm, such as SHA256 or SHA512, you can specify it explicitly:

totp ='your_secret_key', algorithm: 'sha256')


Implementing one-time passwords can significantly enhance the security of your Ruby on Rails application. The ROTP gem provides a convenient and reliable solution for generating and verifying OTPs.

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