Chapter 8: Electronic Payment Systems and Security

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Describe the typical security schemes used to meet the security requirements...

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Nội dung Text: Chapter 8: Electronic Payment Systems and Security

Chapter 8 Electronic Payment Systems and Security © Prentice Hall, 2000 1
Learning Objectives Describe typical electronic payment systems for EC Identify the security requirements for safe electronic payments Describe the typical security schemes used to meet the security requirements Identify the players and procedures of the electronic credit card system on the Internet Discuss the relationship between SSL and SET protocols 2 © Prentice Hall, 2000
Learning Objectives (cont.) Discuss the relationship between electronic fund transfer and debit card Describe the characteristics of a stored value card Classify and describe the types of IC cards used for payments Discuss the characteristics of electronic check systems 3 © Prentice Hall, 2000
SSL Vs. SET: Who Will Win? A part of SSL (Secure Socket Layer) is available on customers’ browsers it is basically an encryption mechanism for order taking, queries and other applications it does not protect against all security hazards it is mature, simple, and widely use SET ( Secure Electronic Transaction) is a very comprehensive security protocol it provides for privacy, authenticity, integrity, and, or repudiation it is used very infrequently due to its complexity and the need for a special card reader by the user it may be abandoned if it is not simplified/improved 4 © Prentice Hall, 2000
Payments, Protocols and Related Issues SET Protocol is for Credit Card Payments Electronic Cash and Micropayments Electronic Fund Transfer on the Internet Stored Value Cards and Electronic Cash Electronic Check Systems 5 © Prentice Hall, 2000
Payments, Protocols and Related Issues (cont.) Security requirements Authentication: A way to verify the buyer’s identity before payments are made Integrity: Ensuring that information will not be accidentally or maliciously altered or destroyed, usually during transmission Encryption: A process of making messages indecipherable except by those who have an authorized decryption key Non-repudiation: Merchants need protection against the customer’s unjustifiable denial of placed orders, and customers need protection against the merchants’ unjustifiable denial of past payment 6 © Prentice Hall, 2000
Security Schemes Secret Key Cryptography (symmetric) Keysender (= Keyreceiver) Keyreceiver Scrambled Scrambled Original Original Internet Message Message Message Message Sender Decryption Receiver Encryption 7 © Prentice Hall, 2000
Security Schemes (cont.) Public Key Cryptography Public Keyreceiver Private Keyreceiver Scrambled Scrambled Original Original Message Internet Message Message Message Message Sender Receiver Private Keysender Public Keysender Digital Scrambled Scrambled Original Original Internet Signature Message Message Message Message Sender Receiver 8 © Prentice Hall, 2000
Security Schemes (cont.) Digital Signature Analogous to handwritten signature Sender encrypts Any receiver with a message with senders public key her private key can read it The receiver is the only A digital signature is one that can read the attached by a sender message and at the same to a message time he is assured that encrypted in the the message was indeed receiver’s public key sent by the sender 9 © Prentice Hall, 2000
Security Schemes (cont.) Certificate Identifying the holder of a public key (Key- Exchange) Issued by a trusted certificate authority (CA) Name : “Richard” key-Exchange Key : Signature Key : Serial # : 29483756 Other Data : 10236283025273 Expires : 6/18/96 Signed : CA’s Signature 10 © Prentice Hall, 2000
Security Schemes (cont.) Certificate Authority - e.g. VeriSign Public or private, comes in levels (hierarchy) A trusted third party services Issuer of digital certificates Verifying that a public key indeed belongs to a certain individual RCA : Root Certificate Authority RCA BCA : Brand Certificate Authority GCA : Geo-political Certificate Authority BCA CCA : Cardholder Certificate Authority MCA : Merchant Certificate Authority GCA PCA : Payment Gateway Certificate Authority CCA MCA PCA Hierarchy of Certificate Authorities Certificate authority needs to be verified by a government or well trusted entity ( e.g., post office) 11 © Prentice Hall, 2000
Electronic Credit Card System on the Internet The Players Cardholder Merchant (seller) Issuer (your bank) Acquirer (merchant’s financial institution, acquires the sales slips) Brand (VISA, Master Card) 12 © Prentice Hall, 2000
Electronic Credit Card System on the Internet (cont.) The process of using credit cards offline A cardholder requests the issuance of a card brand (like Visa and MasterCard) The authorization of card issuance to an issuer bank in which the by the issuer bank, or its designated cardholder may have an account. brand company, may require customer’s physical visit to an office. A plastic card is physically delivered to the customer’s address by mail. The card can be in effect as the cardholder calls the bank for initiation and signs on the back of The cardholder shows the card to a the card. merchant to pay a requested amount. Then the merchant asks for approval from the brand Upon the approval, the merchant company. requests payment to the merchant’s acquirer bank, and pays fee for the The acquirer bank requests the service. This process is called a issuer bank to pay for the credit “capturing process” amount. 13 © Prentice Hall, 2000
Cardholder Merchant credit card Payment authorization, payment data Card Brand Company payment data account debit data payment data amount transfer Issuer Bank Acquirer Bank Cardholder Merchant Account Account Credit Card Procedure (offline and online) 14 © Prentice Hall, 2000
Secure Electronic Transaction (SET) Protocol Sender’s Computer 1. The message is hashed to a prefixed length of message digest. 2. The message digest is encrypted with the sender’s private signature key, and a digital signature is created. 3. The composition of message, digital signature, and Sender’s certificate is encrypted with the symmetric key which is generated at sender’s computer for every transaction. The result is an encrypted message. SET protocol uses the DES algorithm instead of RSA for encryption because DES can be executed much faster than RSA. 4. The Symmetric key itself is encrypted with the receiver’s public key which was sent to the sender in advance. The result is a digital envelope. 15 © Prentice Hall, 2000
Sender’s Computer Sender’s Private   Message Signature Key Message Digest Digital Signature + Message  + Encrypt + Symmetric Key Sender’s Encrypted Certificate Message  Receiver’s Encrypt Certificate Digital Receiver’s Envelope Key-Exchange Key 16 © Prentice Hall, 2000
Secure Electronic Transaction (SET) Protocol (cont.) Receiver’s Computer 5. The encrypted message and digital envelope are transmitted to receiver’s computer via the Internet. 6. The digital envelope is decrypted with receiver’s private exchange key. 7. Using the restored symmetric key, the encrypted message can be restored to the message, digital signature, and sender’s certificate. 8. To confirm the integrity, the digital signature is decrypted by sender’s public key, obtaining the message digest. 9. The delivered message is hashed to generate message digest. 10. The message digests obtained by steps 8 and 9 respectively, are compared by the receiver to confirm whether there was any change during the transmission. This step confirms the integrity. 17 © Prentice Hall, 2000
Receiver’s Computer Receiver’s Private Key-Exchange Key Decrypt  Digital Envelope  Message  Message Digest + Decrypt Symmetric Key +  Encrypted compare Sender’s Message Certificate  Decrypt Sender’s Public Message Digest Digital Signature Signature Key 18 © Prentice Hall, 2000
IC Card Customer y Reader Customer x With Digital Wallets Certificate Authority Electronic Shopping Mall Merchant A Merchant B Payment Gateway Protocol X.25 Credit Card Brand Entities of SET Protocol in Cyber Shopping 19 © Prentice Hall, 2000
SET Vs. SSL Secure Electronic Transaction (SET) Secure Socket Layer (SSL) Complex Simple SET is tailored to the credit card SSL is a protocol for general- payment to the merchants. purpose secure message exchanges (encryption). SSL protocol may use a SET protocol hides the customer’s certificate, but there is no credit card information from payment gateway. So, the merchants, and also hides the order information to banks, to merchants need to receive both protect privacy. This scheme is the ordering information and called dual signature. credit card information, because the capturing process should be initiated by the merchants. 20 © Prentice Hall, 2000