How hard is it to crack the IDEA key?
PGP uses IDEA as the conventional cipher. The key for IDEA is 128 bits. We can calculate the brute force key space with 2^128 = 3.4E38. A special hardware based key cracker for IDEA that can try one billion (1E9) keys per second will take 1.08E22 years to go through all possible keys. You can expect to get most keys in about half that time which will take 5.39E21 years. It is estimated that the sun will go nova in 1E9 years. Since the algorithm is secure, the cryptanalyst has to go after other things like RSA or your passphrase. It is currently beyond our technology to crack an IDEA key by brute force.
