The International Data Encryption Algorithm (IDEA, International Data Encryption Algorithm) was developed by researchers Xuejia Lai and James L. Massey at ETH in Zurich, and a Swiss company Ascom Systec owns its patent rights. IDEA is implemented as an iterative block cipher, using a 128-bit key and 8 cycles. By paying a patent royalty (usually about $6.00 per copy), IDEA can be used widely throughout the world. These fees apply in some areas and not in others. IDEA is considered extremely safe. Using a 128-bit key, the number of tests required in a brute force attack will be significantly larger than that of DES, even allowing testing of weak keys. Moreover, it has shown itself to be particularly resistant to professional forms of analytic attacks.