Breaking ciphers was one of my hobbies growing up the 60's. I wasn't particularly good at it, but I understood the methods used--I read everything I could find

Breaking ciphers was one of my hobbies growing up the 60's. I wasn't particularly good at it, but I understood the methods used--I read everything I could find on the subject that was available in the open literature. See the bibliography below if you'd like to try some interesting cryptography on paper and pencil methods. In graduate school I studied CS and I proposed to my Ph.D. advisor that I would like to do research into cryptography (this was 1983) and he told me that all the interesting things about cryptography have already been discovered and that I should work on something else. In 1983 Byte magazine, volume 3, an article proposed using a program based on the Bazeries Cylinder, see [6, 7], to obtain a practically unbreakable cipher. I didn't own a personal computer at the time, so as soon as I could get together with my best friend, a fellow grad student that owned a PC, we were able to break the cipher in just one evening. (Unfortunately, we were the second to do so and missing out on the $10 prize for the first person that broke the cipher.) There are paper and pencil ciphers that are well designed and are much stronger than the Zodiac Killer's ciphers as I understand them. One designed for Soviet spies, known as the VIC cipher, resisted US cryptographers (as far as I know) and is explained in an interesting Scientific American in the July 1966 edition, see [7]. See also [8]. * Pre-computer age cryptography [1] Helen Fouché Gaines, Cryptanalysis, https://archive.org/details/cryptanalysis00hele https://archive.org/details/cryptanalysis00hele [2] William F. Friedman, Riverbank Publications, https://en.wikipedia.org/wiki/Riverbank_Publications https://en.wikipedia.org/wiki/Riverbank_Publications [3] William F. Friedman, The Friedman Lectures on Cryptography, https://www.nsa.gov/Portals/70/documents/news-features/declassified-documents/friedman-documents/publications/ACC15281/41785109082412.pdf https://www.nsa.gov/Portals/70/documents/news-features/decla... * Interesting historical information, there are so many to choose from now but two of my favorites (one old and one more recent) [4] David Kahn, The Code Breakers, https://en.wikipedia.org/wiki/The_Codebreakers https://en.wikipedia.org/wiki/The_Codebreakers [5] Leo Marks, Between Silk and Cyanide: a Codemaker's Story 1941-1945 (this is less about cryptography and more about the practical problems of secret code and ciphers during WWII). * The Thomas Jefferson wheel cipher or Bazeries Cylinder [6] https://en.wikipedia.org/wiki/Jefferson_disk https://en.wikipedia.org/wiki/Jefferson_disk [7] https://archive.org/details/eu_BYTE-1983-03_OCR/page/n3/mode/2up?q=Bazeries https://archive.org/details/eu_BYTE-1983-03_OCR/page/n3/mode... * The (once) unbreakable VIC cipher [7] David Kahn, Sci American, Vol 215, No 1 (July 1966), pp 38--47. [8] https://en.wikipedia.org/wiki/VIC_cipher https://en.wikipedia.org/wiki/VIC_cipher