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Kryptos - The Cipher (Part 4) - Correctly positioned decryption of the word BERLIN

EASTNORTHEAST - This is not exactly the hint Jim Sanborn (JS) gave for K4 on the 29th of January this year. He only gave NORTHEAST - which refers to the positions 26-34 of K4's plaintext.  Beside BERLIN and CLOCK it is the third revealed plaintext word of K4. However, also this hint does not seem to help much.  However, it just so happened, that a member in the yahoo kryptos group had a conversation with Jim Sanborn due to a submitted solution. Sandborn's answer to the question contained again the last clue which surprisingly was EASTNORTHEAST at position 22-34. Jim Sanborns compass rose at CIA There is disagreement if Jim revealed this on purpose or he did it accidentially, but the new extended clue seem to be serious and valid.Interestingly, EASTNORTHEAST is exactly the direction which is illustrated on the compass rose on one of the stones around kryptos, also created by Jim Sanborn. Actually, i dont really kn...
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[Paper Review] Non-uniform cracks in the concrete: the power of free precomputation

Again, another paper discussion. It is the paper from D.J. Bernstein and T. Lange that will be presented on the Asiacrypt this year. It is a very special paper with the titel "Non-uniform cracks in the concrete: the power of free precomputation". It subtle criticizes the way security proofs are made in the area of provable cryptography. They describe that the current proofs do not cover the free will of an attacker correctly. E.g., they argue, that the proofs do not consider the possibility of precomputation or the option for an attacker to trade success probability for an easier to find algorithm. # Background # Koeblitz and Menenzes did something similar before and they were criticized due to scratching at the base elements of provable cryptography. From my point of view, i can understand both sides and i don't like blaming the other side for having a different opinion. All the achievements in provable cryptography gave us nice and beautiful tools to work with....
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[Paper Review] A new index calculus algorithm with complexity $L(1/4 + o(1))$ in small characteristic.

Scientific breakthroughs are rare events. And I can not directly judge if this is indeed a breakthrough or not, but there are people out there, which do so. It is the paper from Antoine Joux. It introduces a new techniques for the index calculus algorithm and improves the running time to $L(1/4+o(1))$. And it is also the follow up paper by Razvan Barbulescu, Pierrick Gaudry, Antoine Joux and Emmanuel Thomé. The later improves (heuristically) the running time even to quasi-polynomial complexity, i.e., $n^{\mathcal{O}(\log n)}$.
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[Paper Review] Efficient Cryptosystems From $2^k$-th Power Residue Symbols

Today i want to present a paper from the 2013 Eurocrypt conference. The paper is written by Marc Joye and Benoît Libert with the name Efficient Cryptosystems From $2^k$-th Power Residue Symbols [1]. It describes a cryptosystem that is a generalization of the Goldwasser-Micali cryptosystems [2] from quadratic residues to $2^k$-th power residues. The scheme provides indistinguishable encryption under the $k$-QR assumption  a small ciphertext expansion rate  a fast decryption algorithm additive homomorphic operations a (more) efficient Lossy Trapdoor Function Just as the Goldwasser-Micali cryptosystem the Joye-Libert cryptosystems works in the ring $\mathbb{Z}_N$ for a RSA-modulus $N$. The factorization of $N = pq$ is chosen to be $p \equiv q  \equiv 1\pmod{2^k}$. Then they make use of the $n$-th power residue symbol: Definition.  [$n$-th power residue symbol]. Let $p$ be an odd prime and let $n \geq 2$ such that $n | (p-1)$. Then the symbol $$ \bin...
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