Smart cards are a secure alternative to which weak security mechanism?

Biometrics are another form of strong authentication that can be used in conjunction with smart cards, not a weak mechanism replaced by them.

Public Key Encryption is a cryptographic technology that smart cards often utilize to securely store private keys and perform digital signatures, rather than being replaced by smart cards.

Smart cards enhance security by combining something a user possesses (the card) with something they know (a PIN), offering a more robust multi-factor authentication mechanism than relying solely on easily compromised passwords.

While smart cards are a type of security token, the question specifically asks what *weak security mechanism* they replace, and tokens themselves are generally considered strong; the specific weak mechanism replaced is typically passwords.