transitive verb.
To alter (data) using a mathematical algorithm so as to make the data unintelligible to unauthorized users while allowing a user with a key or password to convert the altered data back to its original state.
the GNU version of the Collaborative International Dictionary of English
transitive verb.
to convert ordinary language into code; to hide the meaning of a message by converting it into a form that cannot be interpreted without knowing the secret method for interpretation, called the key.