Cryptography Weekly Newsletter - Tuesday, March 31, 2015

Cryptography newsletter

Top new questions this week: The effect of truncated hash on entropy Suppose i have a 128 bits random binary string (128 bits of entropy), then i hash it using SHA-256, then i take the first 128 bits of the output hash. Does the taken bit string still have (almost) 128 ... hash entropy sha-256   asked by user40602 5 votes answered by fgrieu 3 votes Can machine learning analyze random number generator? I'm studying for random number generators(RNG) and I saw about machine learning a few days ago. So I searched analysis of RNG using machine learning. But I couldn't find such fields. Are there such ... cryptanalysis random-number-generator   asked by Tylor Yoo 4 votes answered by kaepora 1 vote Is this a valid scheme to authenticate through a 'human-readable' certificate? Let's say Alice wants to talk securely to Bob over the internet, and Eve is not only eavesdropping, but has managed to get into a MITM position. In this scheme Alice and Bob exchange $n$ (example $n ... authentication   asked by orlp 2 votes answered by tylo 1 vote During electronic voting, how does one hide the choice from Voting device? Assume the following: I want to cast a vote during an election through an electronic voting system. For our system we make the assumption that the device one uses to cast the vote is potentially ... anonymity voting   asked by WeGi 2 votes Can Poly1305-AES be used with AES-256? I'm reading through Bernstein's The Poly1305-AES message-authentication code. The MAC is predicated on 16-byte block ciphers like AES and produces 16-byte authentication tags. However, Bernstein does ... aes poly1305   asked by jww 2 votes answered by fgrieu 3 votes Stacked LFSR - why not used? New to cryptographic, weak in math. I have designed a PRG which consist of 33 LFSR's, each 32 bits wide. I use one of the LFSR's as "selector", using the 5 LSB from this register to select one of ... encryption cryptanalysis   asked by H. Circlebeach 2 votes answered by kodlu 1 vote Practical brute-force attack on 128 bit encryption In brute-force attack calculations cryptographers say we should assume an attacker will find the key after $2^{(n/2)}$ tries. If n=128, then n/2=64. We know that this is practical (A 64 bit key is ... encryption brute-force-attack birthday-attack   asked by user40602 2 votes answered by Maarten Bodewes 13 votes Greatest hits from previous weeks: Google is using RC4, but isn't RC4 considered unsafe? Why is Google using RC4 for their HTTPS/SSL? $ openssl s_client -connect www.google.com:443 | grep "Cipher is" New, TLSv1/SSLv3, Cipher is RC4-SHA Isn't RC4 unsafe to use? ssl rc4   asked by jonasl 28 votes answered by Thomas Pornin 33 votes How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint? If cryptanalysts today were to crack the original Enigma machine, how fast/ how easily could they do it? What methods would they use? The original cracking was significantly helped by operator ... history enigma   asked by vsz 8 votes answered by e-sushi 9 votes

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