Common Electronic Purse Specifications

Common Electronic Purse Specifications (CEPS) is a specification for a cross-border and cross-currency electronic purse that has so far been based exclusively on proprietary systems and is not compatible with each other.

There are currently electronic wallets in a number of countries: Geldkarte in Germany, Quick in Austria, CASH in Switzerland, Chipknip in the Netherlands, Proton in Belgium, Moneoin France etc. They are all proprietary systems that only allow transactions (charges / payments) on a national / regional / local basis in the respective countries and currencies. The lack of interoperability is the greatest shortcoming of these systems, which means that they cannot serve as cross-border and cross-currency electronic wallets. In addition to the needs of cardholders and acceptors, interoperability has become more important with the introduction of the euro.

The task of defining a standard for cross-border electronic wallets was taken over in 1999 by CEPSCo Llc.

CEPS is an open specification that is available to everyone. CEPS defines requirements for all components for the use of electronic wallets outside the original area of ​​application and for the acceptance of other electronic wallets in their own area of ​​use (in particular card and terminal applications for loading and payments). The main elements are:

1. EMC compatibility,
2. Multi-currency capability,
3. Reconciliation (accountability) and auditability based on a possible transaction link (audit trail),
4. Transaction management
   1. Transaction storage with transmission of all individual transactions that have accumulated in the meantime (clearing all transaction details)
   2. Transaction summation, suppression of individual transaction data and transfer of the sums (aggregation)
   3. Transaction summation, storage of individual transaction data and their provision in the event of a complaint (truncation)
5. Security through public key cryptography with sufficient key length

The CEPS transaction set provides several transactions, of which the load transaction (Purchase), the continuous purchase transaction for partial amounts (Incremental Purchase); the purchase reversal transaction and the currency exchange transaction form the basis.

In addition, CEPS-compatible electronic wallets can be used in e-commerce for secure and anonymous payments, although a card reader is required. However, this will probably be part of the standard equipment of many computers in the future.

It makes sense to connect CEPS to the issue of cards with an EMV chip. This chip enables a CEPS-compatible application for a cross-border electronic wallet stand alone or in addition to an existing application of a proprietary electronic wallet. If two electronic wallets (one for cross-border use and one for national, regional or local use) are established, a common euro memory is possible for the states of the euro zone. In order to establish an electronic wallet based on the CEPS specification, however, the chip requires an RSA co-processor. On the one hand, this would increase the costs, but on the other hand, it would also enable a dynamic card authentication instead of a static card authentication for EMV transactions.

If an electronic wallet has already been established, the upgrading of the terminals accepting the electronic wallet to the CEPS standard will cause considerable costs. These terminals must be equipped with a special CEPS security module that securely handles the CEPS transaction, securely stores the sales data until the data transfer or, in the event of an interruption, securely determines the data still to be transferred. This CEPS security module, like the required terminal software, must be installed on all terminals. An exception is only possible if the CEPS security module does not exist in hardware (as a chip card) but as software and, like the terminal software, can be loaded into the terminals.