spyology

the shadow

Disadvantages of passive interception systems Disadvantages of passive interception systems

Advantages and Disadvantages of passive interception systems:

Many uninformed entities are asking for passive interception systems because they do not want that the interception mission to be detected by the targets. They assumes that the fact that the system transmit signal to the air may cause the detection by the target.

Yes, this 'non transmission' is the benefit of the passive method but this is the only benefit of these systems.

The passive method cause many difficulties and disadvantages. More facts about A5.1 passive interception systems:

1. There are no fully passive real time interception systems for A5.1 today

2. System are detecting the key after minutes

3. All the passive and semi passive system are losing the first conversation

4. If Kc (encryption key) is changing every call the systems can't totally work. There are many GSM operators that change the Kc every call.

5. It can work in larger distances but receive only one side of the conversation

6. For good interception, the system should be very close to the target. Bad reception gives high BERR (bit error rate) that eliminate the possibility to detect the key.

7. The interception and recording of many calls stopped in the middle.

8. The rate of capturing a call is depending on the number of

channels (4+4, 8+8, 16+16,,,,) that the system has relative to the

number of channels in the area.

9. Detection of targets is based on Temporary identification numbers –TMSI. It always nee to be detected and updated.

10. The system collects information only if the target is using the cell phone(talking or SMS)

11. The systems are much much more expensive than active.
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