Monday, June 17, 2024

What are OTPs and Why are They Important for Security?

One-Time Password (OTP) is a single-use password used for user authentication in a security system. This password is generated in real time and is used only once for a specific task. OTPs are critically important for security as they prevent password-guessing attacks and can protect against the theft of users’ personal data.

Two-factor authentication is an important tool for protecting user accounts and confidential information from unauthorized access. It works by using two different factors to verify the authenticity of the user: something the user knows (e.g. password) and something the user has (e.g. token, smart card, or biometric data).

Using two-factor authentication increases security compared to single-factor authentication, where only knowledge of a password is required to access an account. In case of a password leak, an attacker can gain unlimited access to the account and all associated information. However, with two-factor authentication, even if an attacker manages to obtain the password, they still cannot access the account without the second factor.

Thus, the use of two-factor authentication enhances the security of user accounts and protects them from various types of attacks such as phishing, session hijacking, and account takeover using stolen passwords.

There are different types of OTP generation algorithms such as Time-Based OTP (TOTP) and Counter-Based OTP (HOTP) that are used for generating one-time passwords. They are widely used in various industries including finance, healthcare, and the government sector. In this article, we will explore the history of OTPs, the main types of algorithms and their advantages, and also discuss OTP algorithm certifications that play an important role in ensuring security.

History of OTP: When and How Did They Come about?

The idea of using one-time passwords was introduced in the early 1980s in the US banking industry when RSA Security developed and implemented the first commercial algorithm for generating one-time passwords – SecurID.

The algorithm HOTP (HMAC-based One-Time Password) was developed and defined in RFC 4226, which was published in December 2005 by the Initiative for Open Authentication (OATH), which is engaged in the development of open authentication standards on the Internet. However, HOTP had some drawbacks that could be exploited by attackers.

In 2011, the TOTP (Time-based One-Time Password) algorithm was introduced, which is an improved version of HOTP and is considered more secure. The TOTP standard was developed by the same group as HOTP – OATH (Initiative for Open Authentication). TOTP is defined in RFC 6238, which was published in May 2011.

What Are the Main Drawbacks of HOTP Compared to TOTP?

It is desired to analyze the main shortcomings of the HOTP algorithm compared to the TOTP algorithm that stem from the fact that in HOTP, the one-time password retains its validity until successful authentication.

  1. A prolonged time interval for an attack: the one-time password in HOTP is generated in advance and can be used at any time before it is used for system login. This gives the attacker more time to attack and guess the password.
  2. Possibility of generating one-time passwords in advance: when obtaining unnoticed temporary access to the token, the attacker can generate one-time passwords in advance, which may go unnoticed by the token owner.
  3. Token desynchronization: if the user has generated a certain number of one-time passwords (more than 20) and has not used them for authentication, the token may become desynchronized and cannot be used for authentication until certain actions are taken to synchronize the token.

Other OTP Generation Algorithms: OCRA and Their Advantages and Disadvantages

OCRA (OATH Challenge-Response Algorithm) is another one-time password algorithm developed by the OATH organization. OCRA is defined in RFC 6287, which was published in June 2011.
It operates based on challenge-response authentication and uses a secret key to generate one-time passwords. However, unlike TOTP, OCRA can be used not only for login but also for verifying specific operations in the system. OCRA uses parameters that must be known by both the server and the client to generate one-time passwords. These parameters may include the client identifier, the data of the operation being confirmed, the hash function, and other settings.

The client generates a one-time password based on their secret key and the parameters, and the server verifies the password’s correctness using the same parameters. One advantage of OCRA is that it can be configured to generate one-time passwords that are valid only in a specific context. For example, the password may only be valid for performing a specific operation in the system. This increases security and reduces the risk of possible one-time password compromise.

The disadvantage of OCRA is that it may be less convenient to use than simpler algorithms like TOTP. Additional parameters may be required to generate one-time passwords, which can make the setup and usage process more difficult. Additionally, since OCRA is rarely used compared to HOTP and TOTP, there is a chance that it may be less common and supported by fewer applications and devices.

Which Organizations Certify OTP Algorithms and Why It’s Important for Security

There are several organizations that certify OTP algorithms to ensure their compliance with security standards. One such organization is the Initiative for Open Authentication (OATH), which created the standards for one-time passwords. Another organization that certifies OTP algorithms is the FIDO Alliance, which develops open authentication standards. These standards have been certified by various organizations, such as NIST, which confirms their compliance with security requirements.

The certification of OTP algorithms is important for security because it ensures that the algorithms meet specific standards and security requirements, as well as guarantees their compatibility. This ensures that the algorithms can be used securely for authentication and protection against unauthorized access to information. In addition, certification allows users and organizations to choose algorithms that have been tested and verified for reliability, increasing the level of trust in authentication systems.

When choosing an OTP solution, it is important to consider whether it has been certified by reputable organizations. Certified solutions are more likely to provide reliable and secure authentication, which is crucial for protecting sensitive information. Additionally, organizations should regularly review and update their OTP solutions to ensure that they continue to meet evolving security standards and best practices.

Overall, the certification of OTP algorithms and solutions by reputable organizations is an important step in ensuring the security of authentication systems. By choosing certified solutions and regularly updating them, organizations can mitigate the risk of unauthorized access to sensitive information and enhance their overall security posture.

Key Takeaways and Recommendations for Using OTP Algorithms for Security

In conclusion, OTP algorithms are a highly secure and effective method for authenticating and protecting sensitive information. The use of OTPs ensures that only authorized individuals have access to data and resources, thereby reducing the risk of unauthorized access, data breaches, and identity theft.

To ensure the maximum level of security, it is recommended to use OTP algorithms that have been certified by reputable organizations such as OATH and FIDO Alliance. These certifications provide assurance that the algorithms meet specific security standards and requirements.

It is also important to ensure that OTPs are generated and distributed securely, with appropriate measures in place to protect against interception and unauthorized access. This may include using hardware tokens or secure software solutions.

Finally, it is crucial to educate users on the importance of OTPs and how to use them effectively. Users should be trained to recognize phishing attempts, use strong passwords, and follow best practices for securing their devices and accounts.

By following these recommendations and using OTP algorithms properly, organizations can significantly enhance their security posture and reduce the risk of cyber attacks and data breaches.

Generate OTP with! You can also leverage our tool for debugging and diagnosing any authentication-related issues you may encounter. Our free tool supports all standard OATH algorithms. Choose the algorithm that perfectly aligns with your requirements: TOTP for time-based passwords, HOTP for counter-based passwords, or OCRA for challenge-response authentication. At, we provide the flexibility you need to ensure your authentication process is seamless and secure. Visit us now!

Choose your TOTP token


Subscribe our Newsletter for new blog posts & tips. Let's stay updated!


1 comment

Sitterly 24.05.2024 - 12:16

Everything is very open and very clear explanation of issues. was truly information. Your website is very useful. Thanks for sharing.


Leave a Comment


John McHacker

John was a computer programmer and hacker known for his expertise in breaking into secure computer systems. He developed a reputation as a master of computer security and was often hired by companies to test the strength of their cybersecurity measures.

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept