Abstract: OCB operation mode is an authenticated encryption mode.When it is used to process large amount of data with a single block-cipher key it is easy to find collision so that the mode will lose the authenticity capability with high probability.According to this disadvantage an improved scheme on the check sum of authenticity is proposed to reduce the probability of lossing the authenticated capability.The improved scheme can improve the secutity of authenticated capability when collision occurs yet not affect the speed and efficiency of the original scheme.

摘要： 针对具有认证加密功能的OCB模式在单个密钥下处理大容量的数据时容易产生碰撞，降低其认证功能这一缺陷，提出对OCB认证功能校验和的生成方式的改进方案，降低了在碰撞发生时丢失认证功能的概率，在不改变原方案中速度快、效率高等优势的前提下，提高了OCB模式认证功能在碰撞发生时的安全性。