lect03 - Anonymity - Beginnings Early (pre-computer) uses...

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Unformatted text preview: Anonymity - Beginnings Early (pre-computer) uses for social reasons (ability to act more freely, have work accepted without prejudice, etc.) Traffic analysis an issue prior to computers (e.g., Bodyguard of Lies) Computer TAP solvable with cryptography With public-key cryptography, theoretical possibility for anonymity and pseudonymity Forms of Anonymity Traffic Analysis Prevention Sender, Recipient, Message Anonymity Voter Anonymity Pseudonymity Revokable anonymity Data anonymity Anonymity Mechanisms Cryptography Steganography Traffic Analysis Prevention (TAP) Mixes, crowds Data sanitization/scrubbing k-anonymity Adversaries Global vs. Restricted All links vs. some links All network nodes vs. some or no nodes Passive vs. Active Passive listen only Active remove, modify, replay, or inject new messages Cryptography Assumptions All unencrypted contents are observable All encrypted contents are not, without key Symmetric Key Cryptography One key, K ab , associated with entities A and B Same key used for encryption and decryption: C=E(M,K ab ), M=D(C,K ab )=D(E(M,K ab )K ab ) For message M, ciphertext C = {M}K Anyone with K ab can form ciphertext Anyone with K ab can decrypt C For message M, MIC or MAC uses hash fcn If only A and B have K ab , then MAC If group key, then MIC Public Key Cryptography Two keys, K and K-1 , associated with entity A K is public key, K-1 is private key Keys are inverses: {{M}K}K-1 = {{M}K-1 }K = M For message M, ciphertext C = {M}K...
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This note was uploaded on 01/18/2012 for the course CIS 4930 taught by Professor Staff during the Fall '08 term at University of Florida.

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lect03 - Anonymity - Beginnings Early (pre-computer) uses...

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