Various embodiments of the present invention are directed to scrambling-descrambling systems for encrypting and decrypting electromagnetic signals transmitted in optical and wireless networks. In one aspect, a system (1302) for scrambling electromagnetic signals comprises a first electronically reconfigurable electro-optical material (1402) positioned to receive a beam of electromagnetic radiation including one or more electromagnetic signals encoding data. The beam is transmitted through the electro-optical material (1402) and a two-dimensional speckled pattern (1410) is introduced into the cross-section of the beam such that data encoded in the one or more electromagnetic signals is scrambled. System embodiments also include a system (1304) for descrambling scrambled electromagnetic signals, the systems comprising a second electronically reconfigurable electro-optical material (1502) configured to remove the two-dimensional speckled pattern from the beam revealing the one or more electromagnetic signals encoding the data.