By Kim Tae-gyu
Staff Reporter


Is bugging a digital mobile phone possible? The question is currently vexing experts after the country’s spy agency admitted that it had overheard mobile phone calls in the late 1990s.
After purchasing four bugging devices from Italy in 1996, the National Intelligence Service (NIS) said it operated the gear until 1999, when the country stopped using the analog format.

It corresponds with the experts’ consensus that analog phones were prone to bugging because they send and receive voices without encrypting them.

However, the NIS upset experts by saying that it had attempted to carry out mobile surveillance even after Korea introduced the digital wireless system of code division multiple access (CDMA).

Industry experts claimed that digital handsets are dramatically less vulnerable to bugging compared to analog models since the former encrypts all phone calls or messages into computer bits.

The NIS said it tried to overhear mobile calls conducted with digital handsets by two methods _ intercepting radio waves carried from and to cell phones and bugging fixed-line segments between base stations.

``We developed six devices in 1998 to bug mobile phones’ landline connections but their usage was limited because we could only bug 120 lines out of Seoul’s tens of thousands of lines,’’ a NIS official said.

``In Dec. 1999, we built 20 eavesdropping devices that can be carried inside an automobile to intercept radio waves, which were transmitted from the cell phones of bugging targets to base stations.’’

He said the car tried to track the bugging target at a distance of less than 200 meters to continue capturing the radio waves.

He added, however, that the NIS shelved the mobile gear in 2000 as it was not very efficient and the nation’s mobile operators adopted more advanced technology in 2000 called CDMA 2000.

``The equipment has various limitations. In addition, we failed to catch up with the development of the mobile technology for CDMA 2000. So starting in late 2000, we did not use the bugging gear and destroyed it in March 2002,’’ the official claimed.

Even though the NIS insisted it stopped bugging mobile phones in 2000 and never resumed such unlawful activities, suspicions still remain about whether or not the mobile surveillance is possible or is still being conducted today.

Prof. Lee Hyuck-jae at Information and Communication University, who has said mobile eavesdropping is impossible, changed his stance.

``If the NIS could eavesdrop on mobile phones in any fashion several years ago, I think it would certainly have such an ability at the moment,’’ Lee said.

By contrast, the Ministry of Information and Communication still argues that mobile bugging is impractical.

``We still believe eavesdropping on today’s digital cell phones is not just theoretically possible but is almost impossible in reality. We understand the NIS has tried to bug cell phones but failed to find an efficient way,’’ MIC director Yang Jung-hwan said.

To enable mobile calls, networks and facilities of both fixed-line data relay devices and wireless air interface are necessary.

When a person makes a call on a CDMA cell phone, the voice is digitized and encoded to be sent to the nearest base station, which then tosses it to another base station adjacent to the recipient’s via the mobile carrier’s switch operators.

Between base stations, the transmission of voice data is conducted on landlines exactly like that of fixed-line phone calls. In Korea, there are about 23,000 base stations across the nation.

voc200@koreatimes.co.kr