one-time password

In connection with the previous article about the importance of strong passwords and 2-factor authentications we felt the need to dig a little deeper into the topic of OTP (One Time Passwords), and write about time based one-time password (TOTP) and HMAC based one-time password (HOTP) algorithms. As we explained earlier, during 2-factor authentications there are 2 tokens to be provided: one we are all familiar with is the username and the password, while the other one is a secret token that is not known to the public. When it comes to the 2nd factor of authentication mechanisms, usually OTP is used as a protective mechanism.