(OTP) A security system that requires a new password every time a user authenticates themselves. OTP generates these passwords using either the md4 or md5 hashing algorithms.

The equivalent term "S/Key" is a trademark of telcordia technologies, so the name OTP is used increasingly.

See rfc 1760 - "The S/KEY One-Time Password System" and rfc 1938 - "A One-Time Password System".

.