Tuesday, 18 March 2014


Digital cash


Definition: Digital cash is a payment message bearing a digital signature which functions as a medium of exchange or store of value.
Essentially, digital cash mimics the functionality of paper cash. Paper currency and coins represent value because they are backed by a trusted third party, the government and the banking industry. Digital coins will also represent value because they are backed by a trusted third party, usually a bank that is willing to convert digital cash to physical cash.

Unlike real cash digital cash does not have physical existence (paper cash). But digital cash has value that makes possible digital cash exchangeable for paper cash. Digital cash is a transfer protocol for some underling form of money such as real cash.

Actors of digital cash transaction
Actors of digital cash transaction 

                                    Bank                                                Costumer                           Merchant

Digital coin structure
A digital coin consists of the following elements :
  Serial number – a unique number that identifies the coin .
  Denomination – the actual value of the coin .
  Validity Period . 

Structure of digital coin
Structure of digital coin  

How is digital cash stored ?

In off-line digital cash system we need to store digital cash in utilities like smart cards, digital wallet.
                         a) Digital wallet:
·                 It is a database (software) that store account information.
·                 Located on user’s system.
·                 Stores user identification information, digital cash.
·                 Digital wallet can be downloaded from www.cybercash.com. 
b) Smart card :
·                 Card with computer chip embedded on its face.
·                 Stores digital cash.
·                 Have processing capabilities like addition and subtraction.
·                 Used for off-line digital cash transactions.
·                 For example : Visa, Mondex, Octopus, Java.  

Bibliography and References

1. Computer Networks by Andrew S Tanenbaum.


 1. http://www.itd.nrl.navy.miITD/5540/ieee/cipher/cipher-crypto-stds.html
 2. http://ps.superb.net
 3. http://www.cwi.nl/~brands/cash.html
 4. http://www.certicom.cahtml/ecc.htm
 5. http://www.cybercash.com
 6. http://www.digicash.nl

( Full Report ) DIGITAL CASH ( Ms Word ) ( Cover ,Index, Chapters, List of Figures )