Distinguishing between voice traffic and data links

摘要

Techniques are provided for receiving a transmitted first packet that was formatted using a known scrambling algorithm with an unknown scrambling seed. An encoded packet payload is extracted from the first packet header. The encoded packet payload header is decoded to obtain a first scrambled packet payload header. For each potential value of the unknown seed, the first scrambled packet payload header is descrambled to produce a first set of descrambled packet payload headers and for each potential value of initial register values associated with a cyclic redundancy check, the cyclic redundancy check is executed comprising polynomial division on each of the descrambled packet payload headers such that when the polynomial division results in a zero remainder, a potential unscrambled payload header for the first packet is obtained. Information about the first packet is obtained from the potential unscrambled payload header.

主权项

1. A method comprising:
receiving a plurality of packets that were formatted using a known scrambling algorithm with an unknown seed; obtaining a scrambled packet payload header from respective ones of the plurality of packets; for each potential value of the unknown seed, descrambling a packet payload header to produce descrambled packet payload headers; for each potential value of initial register values associated with a cyclic redundancy check, executing the cyclic redundancy check comprising polynomial division on each of the descrambled packet payload headers such that when the polynomial division results in a zero remainder, a potential unscrambled payload header is obtained; and repeating the descrambling and executing processing on subsequently received packets until a desired number of potential seed values are obtained.