格上可撤销的基于身份的加密算法研究

Research on revocable identity-based encryption algorithm on lattice

格上可撤销的基于身份的加密算法(RIBE)不仅能有效地解决实际生活中用户密钥撤销或更新的问题,还能抵抗量子算法攻击,吸引了众多密码学研究者的兴趣。文章通过运用基于近似陷门的非球面高斯采样技术,对RIBE方案中的系统公钥、用户私钥和更新密钥等生成算法进行改进,以缩减密钥尺寸,从而提高方案的空间效率。文章通过对同一水平下的解密错误率与原方案进行比较,可以观察到本方案的主公钥、主私钥、用户私钥、更新密钥和解密密钥的存储空间相较于原方案得到了一定的缩减。特别地,对于不同的安全级别,在保持同一解密错误率前提下,该方案的MPK尺寸缩减了32.29%~41.93%,MSK尺寸缩减了31.25%~38.70%,用户私钥及解密密钥尺寸缩减了59.13%~69.95%,密文尺寸缩减了32.27%~41.91%。

The lattice revocable identity-based encryption algorithm(RIBE) can not only effectively solve the problem of revoking or renewing a user key in real life, but it also resists quantum algorithm attacks, which has attracted the interest of many cryptography researchers. In this paper, the generation algorithms such as system public key, user private key and renewal key in the RIBE scheme are improved by using the aspherical Gaussian sampling technique based on approximate trapdoor. The key size is reduced to improve the spatial efficiency of the scheme. By comparing the decryption error rate with the original system at the same level, it was observed that the storage space of the main public keys, master private keys, user private keys, update keys and decryption keys of this system was reduced to a certain extent compared with the original system. In particular, for different security levels, under the premise of maintaining the same decryption error rate, the size of MPK of this scheme was reduced by 32.29% to 41.93%, the size of MSK reduced by 31.25% to 38.70%, the size of user private key and decryption key reduced by 59.13% to 69.95%, and the size of ciphertext reduced by 32.27% to 41.91%.