Secure Digital Token

A security token (or sometimes a hardware token, authentication token or cryptographic token) may be a physical device that an authorized user of computer services is given to aid in authentication. The term may also refer to software tokens.

Hardware tokens are typically small enough to be carried in a pocket or purse and often are designed to attach to the user's keychain. Some may store cryptographic keys, such as a digital signature, or biometric data, such as a fingerprint. Some designs feature tamper resistant packaging, other may include small keypads to allow entry of a PIN.