格上基于身份的加密算法（Ｉｄｅｎｔｉｔｙ-ＢａｓｅｄＥｎｃｒｙｐｔｉｏｎ，ＩＢＥ）可以抵抗量子攻击，能有效解决公钥密码管理系统效率低的问题，因此，国内外学者提出了一系列基于格的身份加密方案。文章运用Ｊｉａ等提出的基于非球形高斯的原像采样算法，对ＩＢＥ方案中用户私钥的提取进行了改进。实验结果表明，在保证ＩＢＥ加密与解密正确性的情况下，可以有效降低用户私钥的尺寸，提升ＩＢＥ方案的空间效率。文章运用的基于非球形高斯的用户私钥提取算法有２个模式：①采用模式１后，在４２６-ｂｉｔ的安全性下，用户私钥的尺寸由２１７５ｋＢ减小至１３３１ｋＢ；在１０９８-ｂｉｔ的安全性下，用户私钥的尺寸由５０３６ｋＢ减小至３２２５ｋＢ；②采用模式２后，在４２６-ｂｉｔ的安全性下，用户私钥的尺寸由２１７５ｋＢ减小至１０１８ｋＢ；在１０９８-ｂｉｔ的安全性下，用户私钥的尺寸由５０３６ｋＢ减小至２１８６ｋＢ，相比于模式１，模式２能更有效地节省用户私钥的内存开销。

IdentityBased Encryption ( IBE) on lattices resists quantum attacks and effectively solves the problem of low efficiency of public key cryptography management systems, so scholars at home and abroad have proposed a series of latticebased identity encryption schemes. In this paper, the extrac tion of user private keys in the IBE scheme is improved by using the prototype sampling algorithm based on nonspherical Gaussian proposed by Jia, et al. Experimental results show that under the con dition of ensuring the correctness of IBE encryption and decryption, the size of the users private key can be effectively reduced and the space efficiency of the IBE scheme can be improved. The nonspherical Gaussianbased user private key extraction algorithm used in this article has two modes:① After adopting mode 1, the size of the users private key is reduced from 21 75 kB to 13 31 kB under the security of 42 6bit; under the security of 109 8bit, the size of the users private key is reduced from 50 36 kB to 32 25 kB; ② After adopting mode 2, under the security of 42 6bit, the size of the users private key is reduced from 21 75 kB to 10 18 kB; under the security of 109 8bit,the size of the users private key is reduced from 50 36 kB to 21 86 kB, which can more effectively save the memory overhead of the users private key than mode 1.