Secure Socket Layer (SSL)and Secure Electronic Transactions (SET)

Network SecurityFall 2014

http://www.faisalkhan.info/Classes/

Dr. Faisal Kakarfaisal.khan@gatech.edu

Office: Room no. 01, FICT Building

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Application

Transport Layer(TCP,UDP)

Network Layer (IP)

E'net DataLink Layer

EthernetPhys. Layer

Network Layer

E'net DataLink Layer

E'net Phys.Layer

Network Layer

Process Process

Router

Buffers Packets thatneed to be forwarded(based on IP address).

Application

Transport Layer(TCP,UDP)

Network Layer (IP)

Token Ring

Data-Link Layer

Token RingPhys. Layer

Token Ring

Data Link Layer

Token RingPhys. Layer

IPsec IPsec

SSL SSL

HTTPS is HTTP with SSL (Secure Socket Layer).

HTTPS uses the TLS/SSL default TCP port, port 443

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Encrypt

HTTPS

:"Network Security Essentials: Applications and Standards," Prentice Hall, by Wm. Stallings (ECE6612)

Web Browser or Web Server

Fig. 7.3 SSL Record Protocol Operation

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RecordHeader

SSL Handshake - First PartT

ime

Gray areas are optional in some circumstances.5

SSL Handshake - Second PartT

ime

Gray areas are optional in some circumstances.6

Client Server

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SET (Secure Electronic Transactions)

• Provides a secure communications channel among all the parties involved in a transaction: Customer, Seller, Customer’s credit provider, Seller’s bank.

• Provides trust by the use of X.509v3 certificates.

• Ensures privacy because information is only made available to the parties that need it.

* Cardholder account authentication to the Merchant (Cardholder must have a Certificate issued by the credit company). Merchant may issue a temporary Certificate to issue the session is not hijacked).

* Verifies Merchant's relationship with financial institution.

* Integrity of data customer sends to Merchant (order info tied to funds transfer).

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SET - Steps in a Transaction1. Customer opens account with credit company or bank.2. Bank issues X.509 cert. to the Customer with RSA Keys.3. Merchant has two certificates, signing and key exchange.----4. Customer places an order.5. The Merchant sends the customer a copy of his certificate.6. The Customer sends Order Information (OI) encrypted so the Merchant can read it, and Payment Information (PI) encrypted so the Merchant can not read it. ---7. Merchant requests payment by sending PI to the “Payment Gateway” (who can decrypt it) and verifies Customer’s credit.8. Merchant confirms the order to the Customer.9. Merchant ships goods to Customer.10. Merchant sends request for payment to the Payment Gateway which handles transfer of funds.

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Secure Electronic Transactions (SET)

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SET - Dual Signature

The Dual signature allows proof that:

1. Merchant has received Order Information.

2. Bank has received Payment Information and verified the Customer signature.

3. Customer has linked OI and PI and can prove later that PI was not related to a different purchase.

Dual-Sig = E cus-private [ H( H(PI) || H(OI) ) ]

Bob orders a book and a TV from Scam, Inc. Scam, Inc ships Bob the book, and then sends the PI for the TV joined with the OI for the book to the Bank. How does Bob prove to the Bank that he did not order a book with a TV price, when Scam, Inc shows the Bank the OI for the book?

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Customer’s Purchase Request

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Encrypted with Bank’s Public Key

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