Decryption
Decryption was the process of making encrypted data legible again. It could be accomplished with a decryption sequence.

Hoshi Sato, the communications officer stationed aboard , was skilled at decryption. In 2151, an encrypted message was sent to T'Pol, which Ensign Sato decrypted. ()

In 2374,  received a badly damaged message from Starfleet Command. Captain Janeway tried over fifty decryption algorithms on the message without luck, but managed to read the message after designing a new decryption algorithm in the hopes of dealing with a corrupted message from Starfleet. ()

See also
Decoding

Computer programming