Applications of Computers Lecture-3 - PowerPoint PPT Presentation

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  1. Applications of Computers Lecture-3

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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)

  11. 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”

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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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