The Modelling and Analysis of Security Protocols: the CSP Approach

0.7. Digital signatures

These are the analogues in the digital world of conventional signatures and seals of the pen and paper world and supposed to prove the origin and authenticity of the data to which they are bound. Digital signatures are usually implemented using public-key cryptography, though a form of signing that does not provide non-repudiation is possible using private-key encryption. We will stick to the PKC version here. A signature algorithm takes a document and a private key SK and produces a signed document. A signature verification algorithm takes a signed document and a public-key PK and delivers valid or invalid as output. If the output is valid then we should be entitled to conclude that the document was indeed signed with ...