- [nb-NO]Object number[nb-NO]2015.4
- Plaque commemorating the invention of public-key cryptography by James Ellis, Clifford Cocks and Malcolm Williamson at GCHQ. The system was proved by 1975 but kept secret until 1997.
- [nb-NO]Object name[nb-NO]
- [nb-NO]Material[nb-NO]
- [nb-NO]Dimensions[nb-NO]
- l: 460mm
- w: 305mm