Digital Signature Scheme

A digital signature scheme is a cryptographic algorithm that lets a signer bind their identity to a message using a private key, producing a signature that anyone holding the corresponding public key can verify, while remaining computationally infeasible for anyone else to forge. A signature scheme provides authenticity (the message came from the claimed signer), integrity (the message was not altered after signing) and non-repudiation (the signer cannot credibly deny having signed). The (plain) Digital Signature Algorithm, ECDSA, EdDSA and Schnorr signatures are widely cited examples, each built on a different underlying hard problem, most often a variant of the discrete logarithm problem over a finite field or an elliptic curve.