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This page will take the ciphertext resulting from an application of a Vigenere Cipher, and with some presumed key length $k$, produce and analyze the sequence of every $k^{th}$ letter starting with the indicated position. The analysis will include calculating the frequency of each letter in the subsequence, and finding dot products with rotated versions of English frequencies.
Note: As a matter of notation, if English letter frequencies are given by $$(a,b,...,z) = (0.082, 0.015, ..., 0.001)$$ then $$v0 = (0.082, 0.015, ..., 0.001)\\v1 = (0.001, 0.082, 0.015, ...)$$