The Global System for Mobile (GSM) communications, the standard for mobile phones and Internet in 1988, may no longer be so secure after a German hacker team cracked its encryption algorithms.

After cracking the code, Karsten Nohl plans to publish a guide to prompt global operators to improve their safeguards, The Hacker News reported over the weekend.

“With our technology, we can capture GPRS [General Packet Radio Service] data communications in a radius of 5 km," The Hacker News quoted Nohl, head of Security Research Labs, as saying.

Nohl and his team of 24 hackers began working on the security algorithm for GSM in August. He insisted the work was “purely academic."

He used his modified phone to test networks in Germany, Italy and other European countries.

“We have written advice from our lawyers stating that our research is within the legal realm. Obviously the data we produce could of course be used for illegitimate purposes," he said.