A decryption protocol was a set of computer programs that unlocked codes.

Members of the Bajoran militia also had personnel files. They contained a voiceprint, a retinal scan, a psychiatric profile, and a holopicture. In 2371, Quark used a decryption protocol to gain access to Major Kira's personnel file so he could create a holosuite program featuring her likeness for Tiron. (DS9: "Meridian")