Novel technology for monitoring nuclear weapons

Novel technology for monitoring nuclear weapons

In the future, this technology might help verify if countries abide by disarmament treaties.

An inter­na­tion­al IT research team from Bochum, Prince­ton, and Har­vard has devel­oped a tech­nol­o­gy that facil­i­tates the mon­i­tor­ing of changes in nuclear silos with­out hav­ing to reveal secret infor­ma­tion about the stored weapons. In future, it is expect­ed to help ver­i­fy if coun­tries abide by dis­ar­ma­ment treaties. The rooms are phys­i­cal­ly mon­i­tored with radio waves; a sophis­ti­cat­ed cryp­to­graph­ic tech­nique ensures that the process can­not be manip­u­lat­ed.

As far as researchers are con­cerned, no chal­lenge is greater than mon­i­tor­ing nuclear weapons: poten­tial attack­ers in this case are entire nations, rather than small groups of hack­ers or oth­er crim­i­nals. The coun­tries have almost unlim­it­ed finan­cial resources at their dis­pos­al and have access to state-of-the-art offen­sive tech­nol­o­gy.

In the inter­dis­ci­pli­nary project, mem­bers of the Bochum-based Horst Görtz Insti­tute for IT Secu­ri­ty (HGI) col­lab­o­rate close­ly with US-Amer­i­can col­leagues from Prince­ton Uni­ver­si­ty and Har­vard Uni­ver­si­ty. A report about the work has been pub­lished in the sci­ence mag­a­zine Rubin.

Radio wave map indi­cates changes

In order to iden­ti­fy changes in a nuclear silo, researchers deploy elec­tro­mag­net­ic waves in the radio fre­quen­cy range. As they are reflect­ed by walls and objects, a unique radio wave map of the room can be gen­er­at­ed. Every change – for exam­ple if a war­head were to be removed from the stor­age facil­i­ty – would change the reflex­ion pat­tern and could thus be detect­ed. As a result, coun­try A could mon­i­tor the nuclear silos of coun­try B by request­ing radio wave maps of the room in reg­u­lar inter­vals.

How­ev­er, we must make sure that a coun­try can­not gen­er­ate a radio wave map of a ful­ly stocked nuclear silo in advance and then con­tin­ues to send it to coun­try A, even after the weapons had long been removed,” explains Dr Dr Ulrich Rührmair from HGI. To this end, the researchers have inte­grat­ed a so-called chal­lenge into the sys­tem, i.e. a vari­a­tion in the request for a radio wave map between the coun­tries.

Pre­vent­ing decep­tion

In the room that has to be mon­i­tored, 20 rotat­ing mir­rors are installed, which can be remote­ly adjust­ed. The mir­rors reflect the radio waves, thus chang­ing the reflex­ion pat­tern in the room, with each mir­ror set­ting cre­at­ing an indi­vid­ual pat­tern. Pri­or to send­ing the request, coun­try A would arrange the mir­rors in a cer­tain way. In reply, coun­try B would have to send the radio wave map of the room with the exact same mir­ror arrange­ment to coun­try A. This can be done only if coun­try B mea­sures the room live with radio waves and the cur­rent mir­ror set­ting every time. Pre­vi­ous­ly record­ed radio wave maps would be use­less.

Coun­try A can ver­i­fy the reply only if the reflex­ion pat­terns for a num­ber of dif­fer­ent mir­ror set­tings were mea­sured and saved when the tech­nol­o­gy was first imple­ment­ed.

Mir­ror arrange­ment must not be pre­dictable

The IT secu­ri­ty researchers are cur­rent­ly test­ing the sys­tem in a con­tain­er at Ruhr-Uni­ver­sität, using dum­my war­heads and 20 mir­rors. This set­ting enables them to cre­ate bil­lions of sex­til­lions dif­fer­ent mir­ror arrange­ments. “The chal­lenge is to make sure that the mon­i­tored coun­try doesn’t learn to pre­dict the next mir­ror set­ting over time,” says HGI researcher Prof Dr Christof Paar. Were this the case, the coun­try could gen­er­ate the required radio wave map with­out scan­ning the room anew.

In order to pre­vent this sce­nario, the IT experts from Bochum deploy an unpre­dictable cryp­to­graph­ic pro­to­col to align the mir­rors. “The impor­tant thing is to ensure that the cor­re­la­tion between the chal­lenge and the reply can­not be described by a sys­tem of lin­ear equa­tion,” says Zenger. “This is because such sys­tems are rel­a­tive­ly easy to fig­ure out in math­e­mat­i­cal terms.” The same applies to the physics, i.e. the mir­ror mate­ri­als: their reflex­ion prop­er­ties shouldn’t be lin­ear either.