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Although there are already many answers here, I wanted to strongly advocate AGAINST MAC-then-encrypt. I fully agree with Thomas' first half of the answer, but completely disagree with the second half. The ciphertext is the ENTIRE ciphertext (including IV etc.), and this is what must be MACed. This is granted. However, if you MAC-then-encrypt in the ...


Here is a simple/laymans explanation of what the example is (most likely) about: Suppose you are given a new ciphering scheme (set of encryption and decryption algorithms) and you need to find out if it is secure. In cryptography, the security can be analyzed by issuing a challenge to the eavesdropper or adversary $A$. If the adversary wins the challenge, ...


What's the principle to design the functionality, if it aims to a new scene that Canetti hasn't treated? Are the ability to corrupt parties (by some unknown methods) required to be written into the functionality? What else (except the normal functions) should be written into it? Basically, you can design the ideal functionality as you wish. The ...


First, forget about the idea to use this approach for web-browsing. If you want to circumvent censorship while browsing TOR is your way, but can't provide full censorship-freedom. TOR works by establishing a tunnel through the internet (changed evey 10min) via three servers where the first received triple-encrypted contenet, the second double-encrypted and ...


Any peer to peer mesh network would be sufficient. If peers pass messages on to other peers then no peer can no for certain which peer a message is intended for. It would be possible to determine (with some degree of confidence) the source of the message. The real difficulty is handling all the other problems. How do you deal with malicious nodes, denial ...


Pretty much TLS can do this - by encrypting the link to the recipient's mailserver, any intercept would be unable to see the header info (and hence, which user of the mailserver is receiving the mail) Onionskin routing is better at hiding who is sending an email, but usually does not conceal the recipient (as the last hop is normal SMTP)


M.O.Rabin answered the question in 1981, named it oblivious transfer.

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