中文摘要：

该文对4轮KASUMI的f9算法进行了单密钥攻击。把中间相遇攻击的思想用到f9算法攻击中，选取了基础密钥集与穷举密钥集，利用蚝与明文之间的线性关系对f9算法进行了中间相遇攻击，同时利用碰撞与查表技术减少了计算复杂度。最后恢复所有128bit密钥需要数据复杂度是2^32，优化后的计算复杂度是2^125,85，存储复杂度是2^36。

英文摘要：

An attack on f9 algorithm based on 4-round KASUMI is given with a single-key method. The meet-in -the-middle thought is applied into the attack and the based key set and the exhaustive key set are chosen. Then f9 algorithm is attacked with the linear relationship between plaintext and K3. At the same time, collision properties and table-lookups are applied to reduce the time complexity. As a result, with 2^32 plaintexts with the corresponding MACs, the attack needs 2^125.85 f9 calculations with 236 memory to recovery all the key.