Even if ECDSA relies in a PKI, what you do with it is signing and not encryption. The S in ECDSA stands for "signing". Either you don't mean "ciphering" or you

Even if ECDSA relies in a PKI, what you do with it is signing and not encryption. The S in ECDSA stands for "signing". Either you don't mean "ciphering" or you mean an EC encryption algorithm (and not ECDSA). The problem is... why would Lisa cipher her own knowledge with her public key? Only she would be able to decipher with her private key to learn... nothing! PS: I'm from Madrid too!