Digital Signatures (cont.) RSA ENCRYPTION CAN BE USED TO ENSURE MESSAGE AUTHENTICITY AND PREVENT REPUDIATION BECAUSE EITHER KEY IN A PAIR CAN DECRYPT MESSAGES ENCRYPTED WITH THE OTHER. IF ALICE IS CONFIDENT SHE KNOWS BOB'S PUBLIC KEY ... BOB CAN ENCRYPT MESSAGES SENT TO ALICE WITH HIS PRIVATE KEY. IF ALICE CAN DECRYPT SUCH A MESSAGE USING BOB'S PUBLIC KEY, SHE CAN BE SURE HE SENT IT. ALICE CAN ALSO CONVINCE OTHERS BOB SENT THE MESSAGE SINCE HIS PUBLIC KEY IS PUBLIC! UNFORTUNATELY: ANYONE COULD READ BOB'S MESSAGE. ALICE MUST BE SURE SHE KNOWS BOB'S PUBLIC KEY.

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This page is part of a section of lecture slides related to " Authentication " within the topic "Privacy Issues and Encryption". Other slides within this section and other sections of slides for the topic "Privacy Issues and Encryption" can be accessed using the links below. Electronic Privacy Threats Internet Eavesdropping Who can you Trust? Secure Web Communications Traditional Cryptography Encryption Basics Cryptographic Notation The Caesar Cipher Key-based Encryption Schemes Generalizing the Caesar Cipher More Notation Key Properties Vigenere Cypher Vigenere Cypher (cont.) The Key Distribution Problem Public Key Cryptography Public Key Cryptography Public Key Distribution The RSA Cryptosystem Some Details of the RSA Cryptosystem Some Details of the RSA Cryptosystem (cont.) Properties of the RSA Cryptosystem Authentication Authentication Authentication and the Internet Authentication and Cryptography Digital Signatures? Digital Signatures (cont.) Authenticity with Secrecy Certifying Authorities Certifying Authorities (cont.) Data Gathering vs. Privacy "Passive" Privacy Threats HTTP Protocol Headers Server Response Headers Web Browser Headers What are "Magic Cookies"? Magic Cookies Data Mining Passive Privacy and Encryption Techniques Digital Cash Anonymous Internet Financial Transactions Commutative Encryption Blank Bills Withdrawal Symptoms Making Money A Spending Spree