Quote from: eJ3k1 on August 21, 2012, 08:48 amYou have two keys, a private and a public key. Only you have the private key.Now you can do two things:1. Encrypt a message with somebody's public key. - This way only the owner of the private key can decrypt it. This means secure communication.Right.Quote from: eJ3k1 on August 21, 2012, 08:48 amBut you also have another option.2. Encrypt something with your private key. - You can also use your private key for encryption. Then, the encrypted information can be decrypted using the public key. Does that help to keep the information secret? No. Because everybody can decrypt it with your public key. However, because only you have the private key, that means that if you successfully decrypt something with someones public key, it means you can be sure the message came from you (the owner of that private key). That way, it is like a digital signature. You can verify where the message came from. That is also a very useful thing here in this anonymous world.Wrong! Or, to be more accurate, you've got signing and encrypting confused.Public keys are used to encrypt messages and to verify signatures.Private keys are used to decrypt messages and make signatures. Private keys are also used to create the public keys. As public keys are derived from private ones, having the private key means always having the public one and thus being able to encrypt messages to that key.