# GoofyCoin question — why pk, why not sk?

At 45:43 in this video (from the Princeton Coursera Bitcoin and CryptoCurrency Course), they talk about GoofyCoin and show the image below.

My question is, why does it say "signed by pk"... isn't the actual signing done using the "sk", and the verification done using the "pk"?

Update: I think I figured out what's going on here, and am leaving this here for future reference. signed by pk(goofy) means "signed by the identity of goofy" because as mentioned in an earlier video, pk = identity

• The signature is associated / bundled with the public key? Either way, associating with the public key may be easier, as it's now trivial which key has to be used for verification. – SEJPM Oct 7 '16 at 18:56
• I think I figured out what's going on here, and am leaving this for mostly my own future reference. signed by pk(goofy) means "signed by the identity of goofy" because as mentioned in an earlier video, pk = identity. – thanks_in_advance Dec 5 '16 at 4:58