ecdsa – Does every transaction have the same signature?

Bitcoin uses the Elliptic Curve Digital Signature Algorithm (ECDSA). While people in the physical world use their unique signature to authenticate when accepting documents or contracts, digital signatures are cryptographic commitments by the owner of a private key corresponding to one specific message (which in this case is the Bitcoin transaction).

As the inputs to the signature generation algorithm are the message and the private key, different messages produce different signatures.