Transcription

[[Sharon continues to examine the "shadowCoin" source code while Trudy attempts to help. Sharon points at a particular section on the computer monitor.]]
Sharon: If I didn't know any better, I'd almost say this looks like a cosigning subroutine.
Trudy: "Cosigning"? So... it adds another signature to something?

Sharon: Possibly. The whole basis for this "shadowCoin" cryptocurrency is digital signatures. When you make a transaction, it gets signed with the wallet's private key.

Sharon: However, it looks like this code applies a second, hard-coded secret signature to every transaction.
Trudy: [Surprised] What does that mean?
Sharon: Right now, I have no idea.

Trudy: [Suspicious] What would adding a second signature accomplish?
Sharon: [Concentrating] Other than inserting the owner of the second key into each and every transaction? Almost anything...