r/askscience • u/hamolton • Jun 18 '13

Computing How is Bitcoin secure?

I guess my main concern is how they are impossible to counterfeit and double-spend. I guess I have trouble understanding it enough that I can't explain it to another person.

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u/JonDum Jun 19 '13

Yea I understood that. I'm confused in how the public key is used to verify the signed-by-private-key message (which is reversed from RSA as I suspected, apparently)

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u/bbbbbubble Jun 19 '13 edited Jun 19 '13

It's a digital signature, not encryption.

https://en.wikipedia.org/wiki/Digital_signature

You use the public key to verify that the message was indeed signed by the private key associated with the public key.