\section{EdDSA Signatures}\label{eddsa}
With signatures, authenticity and non-repudiation want to be achieved. In this
context hashes and public key cryptography are used.\cite{hash2012} For this
purpose the Donau uses EdDSA signatures. The Edwards-curve Digital Signature
Algorithm or for short EdDSA is a scheme for digital signatures based on the
twisted Edwards elliptic curves and the Schnorr signature scheme. EdDSA
signatures using the curve Curve25519 are also called Ed25519. The Donau only
uses Ed25519. Whether Curve25519 or the Edwards-curve, the scheme is very
efficient and secure.\cite{BernsteinEd25519}

