On Monday 20 Sep 2010, Rony wrote:
I am just curious to know the advantage of using the PGP signature. Does it authenticate you better or result in no bouncing or rejection of mails by spam guards? Suppose I copy and paste the text in a fake email like the one below, I will appear to have the same authentic signature. So what is the safety or advantage?
Signing a message establishes 3 things:
1. That the contents of the message have not been tampered with in any way. Alternatively, if the signature doesn't verify, it establishes that the contents HAVE been tampered with.
2. Non-repudiability. In theory, a properly-signed message establishes that the message was created by the person to whom the key belongs. The person cannot later deny authorship of the message.
3. Ownership and time stamp. Related to (2), a properly-signed message establishes the person as the originator of the message. You may want to do this if you are, for example, proposing an original and useful idea in a message -- once it's signed, no one will be able to later claim they published the idea before you.
BTW, GPG/PGP-signing a message also automatically timestamps it.
Regards,
-- Raj