“In almost all transactions that we take part in on a daily basis we are not proving our identity, we are proving that we are authorised to do something whether it is to charge money to a line of credit in a shop, ride a bus or open the door to an office. In these cases we are using ID as a proxy because we don’t have a proper infrastructure in place for allowing us to keep our identities safely under lock and key while we go about our business. What you should really be presenting at the polling station is an anonymised entitlement to vote that you can authenticate your right to use. It is nobody at the polling station’s business who you are and, in common with many other circumstances, if you are required to present your identity to enable a transaction then we have created another place where identity can be stolen from.”
source via Tom Loosemore
Hence my thinking that every voting opportunity be accompanied by a securely generated voting-token which expires upon use. This can be further strengthened with some kind of two factor authentication which can be activated on the spot, still, without a need for identity per-se.