# jemdoc: addcss{rbh.css}, addcss{jacob.css} = ch7: pretty good privacy ~~~ {}{raw} digsig ~~~ ~~~ {pretty good privacy} - information age: who encrypts ? -- government military business crime -- citizens ? - Phil Zimmermann -- 1970s Florida Atlantic University -- 1977 RSA: government military business (costly) -- until then, large scale gov\'t privacy invasion prohibitive -- 1980s developed pgp -- 1991 asks friend to post pgp on internet -- 1993 US govt visits Phil ~~~ ~~~ {pgp features} - msg: symmetric secret-key cryptosystem - secret key: asymmetric public-key cryptosystem - signature: asymmetric public-key cryptosystem - automated pkc key generation, session key ~~~ ~~~ {spoofing} - e.g. Eve uses Alice's RSA public key, sends Alice this message: ~ Hi Alice, this is Bob. I would like to purchase an expensive gift for Eve. Please send the gift directly to Eve, and charge my account. Thank you. Bob. ~~~ ~~~ {}{raw}