I would have attended your birthday party last night but for the fact that it    at that time．

A．was raining

B．would rain

C．had rained

D．had been raining

下列关于公钥分发的描述中，错误的是( )。

A．分发公钥不需要保密

B．分发公钥一般需要可信任的第三方

C．数字证书技术是分发公钥的常用技术

D．公钥的分发比较简单