Keyword ciphers like the one leading with "abcdefghijklmnopkrstuvwxyz" are used for: Periodic GROMARK - The Black Chamber
Because it is a substitution cipher, common letters (like 'E' or 'T') will still appear frequently, just represented by different letters. abcdefghijklmnopkrstuvwxyz
: The word "alphabet" is derived from the first two letters of the Greek alphabet, alpha and beta . abcdefghijklmnopkrstuvwxyz
When examining a cipher, such as those found on this reddit thread or in this university PDF , frequency analysis is crucial. Breaking the Cipher abcdefghijklmnopkrstuvwxyz