一种改进的格上CCA安全的密码方案

An Advanced CCA Secure Cryptographic Scheme Based on Lattice

改进了Peikert C的一篇经典文章中基于格的CCA安全的公钥密码方案.在保持经典方案加解密速度快、密文扩展率低,能够进行公开的密文完整性验证,能够实现块加密的优良性质不变的基础上,把方案中陷门函数生成的两组实例巧妙地变换成只生成一组实例,并且对新方案的正确性和新方案在标准模型下的CCA安全进行了严格地证明,最后比较了两种方案的密钥长度.新方案的公钥长度和私钥长度较Peikert C的方案有显著地缩减.因此,新方案克服了经典方案中密钥长度太大的严重缺陷,在方案的效率上有了大幅度提高.

This paper improves the classical CCA secure public key cryptographic scheme based on lattice by Peikert C. This new scheme can maintain its graceful properties of public ciphertext integrity verification,block encryption and a high encryption /decryption speed and a low encryption blowup factor. What＇s more,this new scheme decreases the public key length and secret key length of the scheme in large scale by altering its double groups instance to single on the premise of its validity and security,which are the most important limitations of the scheme. Therefore we get a huge improvement in its efficiency.