1. To establish, usually by challenge and
response, that a
transmission attempt is authorized and valid.
2. Verify the identity of a
user, user device, or other entity, or the integrity of
data stored, transmitted, or otherwise exposed to unauthorized modification in an
automated information system, or establish the validity of a transmitted
message. [
NIS]
3. A challenge given by voice or electrical means to attest to the authenticity of a message or transmission. [
JP1]