there are so many similarities to PGP and Bitcoin. Is it possible to encrypt a message using my public key, and decrypt it using my private key? Like PGP does. It would be something very nice to do, as Bitcoin clients are much more common and widespread than PGP related software (also easier to use).
PGP/GPG is a good idea, but encrypting messages is only a small part of the concept.
The real idea is that it's basically a p2p id system, not just for encryption. It works like this:
- Find people you know well
- Get them using PGP
- Put your public keys in a public place on internet
- All your buddies attach a little text to your key, and sign the text with their key
- The text should say something like "We went to school together since 5 years old", or "she's my aunt" etc
That's great for you guys, you all have cryptographically signed messages of everyone in your little group, saying how you know each other. Which is actually not so great, as you're just signing info all of you already know!
But the power comes in later; when someone you
don't know gets into the group, you're likely to trust your friend who signs their message that brings them into the group, and so you'll believe the message about how they know each other.
And if the newcomer is coming from another group of PGP buddies, then you have a link between your group and theirs, and you've got some kind of assurance that these people are who they say they are, and that they trust that about one another.
This is the so-called Web of Trust, and it never quite got moving.
But, it does keep growing, and especially among computer programmers. The biggest group of PGP users who are all cross signing each others keys is around 60,000 or 70,000 people. A bit like with Bitcoin, more people doing the cross-signing thing makes the whole system stronger and more valuable. It's totally p2p, so just because the biggest group now is those 60,000 people, does not mean another big group couldn't grow to the same size (although there is a big incentive for the 2 group to merge, and nothing to stop 2 people from each big group cross-signing each others keys to make that merge happen, something a bit like that no doubt happened already)
PGP is a bit slow in development, and as you say, not the most user friendly. But you only have to learn it once, and you've got a different kind of infrastructure to Bitcoin, that's just as powerful, but for a different purpose.
to answer the actual question though:
I'm not sure if ECDSA can be used to encrypt, I thought it was only possible to use it to sign with? (the DSA part breaks out as
Digital
Signature
Algorithm)