关键词: 电子公文, 加密, 安全性, RSA（Receive, Shamir, Adleman）公钥密码

Abstract: With the development of information technology as well as the in-depth implementation of e-government,  a lot of safety questions are resulted. RSA encryption technique is an important technique used in the transfering safely information. Based on RSA public-key code methods,  this paper proposes an encryption algorithm of electronic official documents. In this algorithm, a weak key of the RSA cryptosystem is found. It turns out that the modulus of the RSA cryptosystem is easy to factor if the the ratio of the two prime factors of the modulus can be well approximated by a small fraction.

Key words: electronic official documents, encryption, safety, RSA public-key code