Seize The Index Of Coincidence And Its Applications In Cryptanalysis (Cryptographic Series , No 49) Curated By William F. Friedman Format Brochure

A revision of a paper with the same title published inby the Riverbank Laboratories, this material was classified Confidential for overyears.
This book provides two examples of cryptanalytic solution by means of tabulating coincidences and calculating their significance, One example deals with a substitution cipher wherein a series of messages employing up torandom mixed secondary alphabets can be solved without assuming a plaintext value for a single cipher letter.
Another example deals with a "multiple alphabet, combined substitutiontransposition" cipher, solved from but a single message of fair length.
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