In Europe and North America, the most widely used stream cipher to ensure privacy and confidentiality of conversations in GSM mobile phones is the A5/1. In this paper, we present a new attack on the A5/1 stream cipher with an average time complexity
of 2^(48.5), which is much less than the brute-force attack with a complexity of 2^(64). The attack has a 100% success rate and requires about 5.65GB storage. We provide a detailed description of our new attack along with its implementation and results.
