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...
This blog post is about De Bruijn sequences and its relationship to cryptography. We focus here on De Bruijn sequences over the alphabet $A=\{0,1\}$. Definition [De Bruijn sequence (binary)] . A binary string of length $2^n$ is called a De Bruijn sequence of order $n$ if each possible $n$-bit string occurs exactly once (incl. wrap-around) as a substring. Picture 1 - DeBruijn graph for n=3 De Bruijn sequences are the shortest possible bitstring that contains all possible $n$-bit substrings. For each $n$ there are $$\frac{2^{2^{n-1}}}{2^n}$$ possible De Bruijn sequences. For example, a De Bruijn sequence of order $n=3$ is $$00011101$$ and of order $n=4$ is $$0000101100111101$$ There are several ways to create De Bruijn sequences. One way is walk along an Hamiltonian Cycle in the corresponding De Bruijn graph (see Picture 1) . A De Bruijn graph is a directed graph of degree $2$ which has $2^n$ vertices. There is an edge from vertex $i$ to the two vertices $$(2i\;...