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## PowerPoint Slideshow about ' Applications of Computers Lecture-3' - Gabriel

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E-Commerce

- Almost all major companies have their homes on the web, mainly for advertising
- Companies were reluctant towards e-commerce but now it is picking up
- The most revolutionary e-commerce is between business and customer
- Business-business e-commerce is already developed

E-Commerce Requirements

- E-commerce between customer and business requires several functions
- For example, auction sites should have the capability to track bids by various people
- Also, multi-vendor selling sites should support tracking of multiple companies
- Transactions between customers and the e-commerce site should be safe and secure

The Credit Card Concerns

- Almost all e-commerce sites offer credit card support
- A customer who wants to buy something pays with credit card
- The credit card information is transmitted through the public network and it can be tapped by someone in the middle

Encryption and Data Security

- For successful e-commerce, we must ensure that the sensitive data has been encrypted and secured
- Encryption transforms the data using a “key” into a value that is meaningless in its normal form
- This encrypted value can only be decrypted by authorized agency or person

Securing the Connection

- For protecting the credit card info, it is transmitted under SSL (secure sockets layer)
- It means the card info is encrypted and it is very difficult to break the code by an intruder
- Surprisingly, the misuse of the card info by employees is a more serious concern

Encryption and Data Security

- For successful e-commerce, we must ensure that the sensitive data has been encrypted and secured
- Encryption transforms the data using a “key” into a value that is meaningless in its normal form
- This encrypted value can only be decrypted by authorized agency or person

Encryption Basics

- For encryption, XOR logical operation is widely used
- The data to be encrypted is XORed with the key
- XOR has the property that it can transform a binary value into another totally different value. This encrypted value is sent instead of the original value
- The recipient performs XOR of the received encrypted value with the key, restoring original value

Class Example

- The data to be sent is: 0111 1011
- The 4-bit key is 1010
- SENDER: Encrypt the data and send it to the recipient
- Encrypted Data is obtained by repeatedly performing XOR operation with the key
- First Four bits 0111 XOR 1010 gives the result 1101

Class Example

- Next Four bits 1011 XOR 1010 gives the result 0001
- RECIPIENT: Decrypt the data
- First Four bits 1101 XOR 1010 gives the result 0111 (original data recovered)
- Next Four bits 0001 XOR 1010 gives the result 1011 (original data recovered)

Encryption Keys

- There are two types of encryption schemes in use
- In symmetric or secret key ciphers, the encryption and decryption keys are symmetric and identical
- As an example, consider this diagram then encrypt following message with your own encryption scheme
- “Please transfer six million dollars into my checking account”

Symmetric Cipher

Adapted for academic use from “Exploring The Digital Domain” by Abernethy Allen, ITP 1999

Symmetric Cipher

- In symmetric secret key cipher, the key must be sent to recipient, otherwise the message cannot be decrypted
- Sending the key on public network is like putting your house key in locksmith’s shop and allowing everyone to duplicate it
- Alternatives are to restrict access to secret key to a few individuals

DES

- DES (Data Encryption Standard) is one example of symmetric key encryption
- DES uses a 56-bit key which can be doubled in length to 112 bits
- Breaking messages encrypted with DES would require a considerable amount of computing time and effort

Alternate Payment Methods

- DIGICASH is an alternate payment method that does not use credit cards for online buying
- Customer opens an account and an electronic wallet is created at customer’s machine
- Customer is able to create digital coins that are certified by the bank

Digicash is now eCash

- http://www.ecashtechnologies.com/
- The new p2p technology is developed by the eCash technologies
- Refer to the link below:
- http://www.ecashtechnologies.com/Solutions/p2p.asp

Alternate Payment Methods

- The bank attaches a digital signature to each digital coin
- Thus, the customer can send digital cash to the vendor and buy anonymously
- VIRTUAL PIN allows credit card charges without transmitting card number
- The bank holds customer’s credit card information and issue a virtual PIN to customer

Alternate Payment Methods

- Customer specifies virtual PIN to a merchant when charging something to credit card
- Merchant sends this PIN to bank for verification
- Bank requests customer authorization via email and on confirmation, charges the amount of sale to customer’s credit card

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