eCash

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eCash was the protected brand name of an electronic payment system from DigiCash . It was particularly suitable for payments in the micropayment area. A type of voucher system was used in which each digital coin is anonymously represented by a digital serial number that was stored on the user's hard drive . At the end of the 1990s, the system and the company behind it were shut down.

The inventor of eCash, David Chaum , originally wanted to create an Internet system that could be used to hold political elections. For the output of the electronic “ballot paper” it was important that the issuing body could be authenticated, that the user remained anonymous and that it could only be used once. Since the idea of ​​electronic voting did not meet with any response at the time, Chaum looked for another application of his system. Since similar requirements also apply to means of payment, he used the principle for eCash.

procedure

With the eCash procedure, a customer transfers credit from their bank account to their eCash account. In doing so, encrypted files with certain value memories are generated that are saved on his computer. These electronic coins are managed by a special utility, the "electronic wallet" ( cyber wallet or e-wallet). When shopping on the Internet, these files are then sent to the seller from the buyer's computer. When paying, the digital cash is immediately checked for validity by the seller or the bank. The seller can now arrange for the ordered goods to be dispatched or for the corresponding service to be carried out.

function

First, a customer must open an eCash account with a bank licensed for eCash and install eCash software on their computer. The eCash account is linked to an actual bank account. The “loading” or “unloading” of an eCash account can only be done from this bank account. If the customer would like to transfer an amount to eCash, the electronic wallet generates files for the desired amount. Each file is assigned a certain value that no longer changes. She also receives a serial number from the wallet. DigiCash therefore calls these files “electronic coins” ( cybercoins ). The bank checks the balance. If it is sufficient, each file is provided with a key from the bank, with each key corresponding to a certain value; the corresponding amount is debited from the "real" bank account. Then the files are sent to the customer, i. H. sent back to the wallet. This process roughly corresponds to charging a chip card at a charging terminal. The files are now encoded both by the wallet with the customer key and by the bank with its key. The wallet will now remove the key it has attached. DigiCash calls this process "blinding". The blinding ensures absolute anonymity. Each file thus consists of the serial number and the information about the value and is encrypted with the bank's key. When spending eCash, the customer sends files whose value corresponds to the amount requested by the seller. Payment on the Internet using the eCash software is possible in real time. With a click of the mouse, the seller's software generates a payment request, which he sends to the customer's wallet. This lets the customer confirm the transaction and sends files to the seller in the amount of the desired amount. This in turn forwards the electronic coins to the bank. There the bank key is removed and the value of the coin is credited to the seller's eCash account. The now decrypted serial number is saved.

The naming of this invention gives the impression that it is cash - although the fixed connection between the system and a real bank account only converts so-called giro deposits into eCash. The merchant also needs an eCash account for his credit posting. This is important insofar as all critical areas such as money laundering, issuing means of payment etc. do not pose a problem with it. Actually, eCash is more like a bank guarantee than a money system.

Pros and cons

A double use ( double-spending ) of the files is impossible, because as soon as a serial number has been used, it can never be used again. The monetary value cannot be lost if the user has secured his key or the e-wallet and can thus restore the wallet via the bank server (recovery mechanism). No cases of abuse were reported during the time that eCash was in use. The maximum credit amount on the e-wallet was limited to around EUR 200.

Although technically excellent, the eCash system has not become very widespread because DigiCash slipped into a US settlement procedure (Chapter 11) and the cryptological patents were taken over by a successor company. This has focused on the voucher / online voucher system regionally in the USA. The European eCash license banks, where the systems were already operating perfectly (Deutsche Bank, Bank Austria and Credit Suisse), then ended their eCash support at the end of the 1990s. The problem of converting between currencies was never solved in the eCash system until the very end.

PayPal works in a similar organizational way today: the debits are made from credit cards and bank accounts and the merchant is given a guarantee for the credit. A PayPal merchant credit can also only be transferred back to a real bank account or spent in the system itself. The eCash features, which were very advanced at the time, such as the transmission of digital coins by email and the possibility of two private individuals sending each other amounts of money, are also covered by PayPal.

literature

  • Applied cryptography. Protocols, Algorithms and Source Code in C . Pearson Studium, 2005 ISBN 3-8273-7228-3 , pp. 166-176.
  • Richard A. Mollin: RSA and Public-key Cryptography. 2002, ISBN 1-58488-338-3 , pp. 143-148.
  • David Chaum : Blind signatures for untraceable payments, Advances in Cryptology - Crypto '82. Springer-Verlag, 1983, pp. 199-203.
  • D. Chaum, A. Fiat, M. Naor: Untraceable electronic cash. In Proceedings on Advances in Cryptology (Santa Barbara, California, United States). S. Goldwasser, Ed. Springer-Verlag New York, New York 1990, pp. 319-327. online ( Memento from March 20, 2009 in the Internet Archive ) (PDF; 354 ​​kB)
  • S. Goldwasser , M. Bellare : Lecture Notes on Cryptography. Summer course on cryptography, MIT, 1996-2001, p. 233 ff.

Payment method studies

  • Markus Breitschaft, Thomas Krabichler, Ernst Stahl, Georg Wittmann: Secure payment methods for e-government. In: Federal Office for Security in Information Technology (Ed.): E-Government-Handbuch. Bundesanzeiger Verlag, 2004. Updated version May 2005, ISBN 3-89817-180-9 .
  • Ernst Stahl, Thomas Krabichler, Markus Breitschaft, Georg Wittmann: Payment processing on the Internet - meaning, status quo and future challenges . Regensburg 2006, ISBN 3-937195-12-2 . (More on the study and management summary as PDF)
  • Georg Kristoferitsch: Digital Money - Electronic Cash - Smart Cards. Opportunities and risks of payment transactions via the Internet. Ueberreuter, Vienna 1998, ISBN 3-7064-0421-4 .

Web links

Individual evidence

  1. ↑ "eCash" is only available as a (European) figurative mark (CTM 001670975) from an eCash, Inc. in the USA. The trademark registrations for DigiCash as a word mark were either rejected due to the need to keep them free (DE 30025387.7, 39723633.6) or withdrawn by DigiCash (CTM 000685404). In this respect, the term eCash was never a protected brand name in Germany