One scheme,PGP,for Pretty Good Privacy,has become an almost de facto standard since it wasfirst offered in 1991 as free software by its creator,Phil Zimmermann.

• 一种叫PGP(系极好隐私性的英文编写)的方案,自它1991年由其开创者Phil Zimmermann按免费软件提供使用以来,几乎成了事实上的标准。