HOTPmenetelmiä

HOTPmenetelmiä refers to methods and techniques used in the context of HOTP (HMAC-based One-time Password). HOTP is a standard for generating one-time passwords based on a shared secret key and a counter. The HOTP algorithm produces a sequence of passwords that are different each time but can be verified by both the client and the server.

The core principle of HOTP is cryptographic hashing. Both the client and the server maintain a secret key and a counter value. When a user needs to authenticate, the HOTP algorithm is applied to the shared secret and the current counter value. This generates a unique, time-limited password. After successful authentication, the counter on the server is incremented. The client also increments its counter, ensuring synchronization. This counter-based approach distinguishes HOTP from time-based one-time password (TOTP) algorithms, which rely on the current time.

Various implementation methods and libraries exist for HOTP. These are often integrated into authentication systems for enhanced security. Examples include hardware tokens that generate HOTP codes, and software applications that manage the secret key and counter to produce the codes on demand. The security of HOTP relies heavily on the secrecy of the shared key and the proper synchronization of the counters. If the counters become desynchronized, the authentication process may fail until they are resynchronized, often through a specific resynchronization process. The length of the generated HOTP code can typically be configured, with common lengths being 6 or 8 digits, affecting the level of brute-force resistance.