DES encryption was a form of data encryption used by CTU Los Angeles. It used a single key.
When performing a capability search at the beginning of Day 3, Kim Bauer asked Adam Kaufman if the link file had DES encryption on it. He replied that it didn't, as it had a two-key encryption instead. She asked him where the filter was stored, and he told her it was in the Études 7 volume. ("Day 3: 1:00pm-2:00pm")
