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Encryption

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  • 1. Zeeshan KhalidENCRYPTION
  • 2. SYMMETRIC KEY ENCRYPTIONAlso known as secret key encryption• Both the sender and receiver use the samedigital key to encrypt and decrypt message• Requires a different set of keys for eachtransaction• Advanced Encryption Standard (AES):– Most widely used symmetric key encryptiontoday; offers 128-, 192-, and 256-bit encryptionkeys; other standards use keys with up to 2,048bits
  • 3. PUBLIC KEY ENCRYPTIONSolves symmetric key encryption problem of having to exchangesecret key• Uses two mathematically related digital keys – public key (widelydisseminated) and private key (kept secret by owner)• Both keys used to encrypt and decrypt message• Once key used to encrypt message, same key cannot be used todecrypt message• For example, sender uses recipient’s public key to encryptmessage;recipient uses his/her private key to decrypt it
  • 4. PUBLIC KEY CRYPTOGRAPHY – A SIMPLE CASE
  • 5. PUBLIC KEY ENCRYPTION USINGDIGITAL SIGNATURES AND HASH DIGESTS• Application of hash function (mathematicalalgorithm) by sender prior to encryptionproduces hash digest that recipient can useto verify integrity of data• Double encryption with sender’s private key(digital signature) helps ensure authenticityand nonrepudiation
  • 6. LIMITS TO ENCRYPTION SOLUTIONS• PKI applies mainly to protecting messages intransit• PKI is not effective against insiders• Protection of private keys by individuals maybe haphazard• No guarantee that verifying computer ofmerchant is secure• CAs are unregulated, self-selectingorganizations
  • 7. SECURING CHANNELS OF COMMUNICATIONSecure Sockets Layer (SSL):– Most common form of securing channels ofcommunication; used toestablish a secure negotiated session (client-server sessionin which URL of requested document, along withcontents, is encrypted)• S-HTTP:– Alternative method; provides a secure message-orientedcommunications protocol designed for use in conjunctionwith HTTP• Virtual Private Networks (VPNs):– Allow remote users to securely access internal networksvia the Internet, using Point-to-Point Tunneling Protocol(PPTP)
  • 8. SECURE NEGOTIATED SESSIONS USING SSL
  • 9. PROTECTING NETWORKS: FIREWALLS ANDPROXY SERVERS• Firewall: Hardware or software filterscommunications packets; prevents somepackets from entering the network based on asecurity policy• Firewall methods include:– Packet filters– Application gateways• Proxy servers: Software servers that handle allcommunications originating from or being sentto the Internet
  • 10. FIREWALLS AND PROXY SERVERS
  • 11. PROTECTING SERVERS AND CLIENTSOperating system controls: Authentication andaccess control mechanisms• Anti-virus software: Easiest and leastexpensive way to prevent threats to systemintegrity
  • 12. POLICIES, PROCEDURES & LAW:DEVELOPING AN E-COMMERCE SECURITY PLAN