Digital signatures [DH]—unlike handwritten signatures and banknote printing—are easily copied exactly. This property can be advantageous for some uses, such as dissemination of announcements and public keys, where the more copies distributed the better. But it is unsuitable for many other applications. Consider electronic replacements for all the written or oral commitments that are to some extent personally or commercially sensitive. In such cases the proliferation of certified copies could facilitate improper uses like blackmail or industrial espionage. The recipient of such a commitment should of course be able to ensure that the issuer cannot later disavow it—but the recipient should also be unable to show the commitment to anyone else without the issuer’s consent.
- [C]Chaum, D., “Blinding for unanticipated signatures,” Advances in Cryptology—EUROCRYPT’ 87, D. Chaum & W.L. Price Eds., Springer Verlag, 1987, pp. 227–233.Google Scholar
- [CE]Chaum, D. and J.-H. Evertse, “A secure and privacy-protecting protocol for transmitting personal information between organizations,” Advances in Cryptology—CRYPTO’ 86, A.M. Odlyzko Ed., Springer Verlag, 1987, pp. 118–167.Google Scholar