Same here, but I think you meant DPGPT. There are many, many other words with that pattern, (at least 185, including proper names) but there is one that is much more common. Once you try it, the puzzle is automatic.
As the result of on a discussion on this thread last weekend I found a very interesting book on cryptography, link below. I think all the participants here would enjoy it. I borrowed a copy from Minuteman Library systems, which includes about 100 libraries in eastern Massachusetts. There were only two copies, one in Brookline, one at Dean College. The copy I got, which came from the Dean College Library, looked like it had barely, or even never, been opened. I picked it up Friday.
The treatment is slightly mathematical, but not particularly dense.
Chapter 2 covers Monoalphetic Substitution Ciphers (MASC), of which cryptoquotes are an example. Cryptoquotes simplify things by providing punctuation and spaces. He includes a simple test for vowels, that is probably not useful for solving these puzzles, but is of some interest, and easy to implement on a computer. It consists of identifying the number of different letters any letter in the ciphertext is next to. The letters with the highest number of associations are probably vowels. Combinations in plaintext like BZ and XK are rare, but vowels pair with anyting.
Chapter 3 explores polyalphabetic subsititution ciphers, including the Vigenère cipher, and running key ciphers. Running key ciphers use a key length as long as the message. Cryptoquotes and other MASC, for example, have a key length of one. A Vigenère cipher increases the key length, but has the weakness that every substitution alphabet is a Caesar code. One popular form of running key is using a book as the key. He shows simply and clearly why this is actually a very poor form of key. After only eight characters, the probability of decryption by brute force is almost 100%.
Another form of running key cipher that is indecipherable without the key is the one time pad, using a random key. (Assuming the key is truly random. German diplomatic - not enigma - ciphers in use during World War II used a defective random key generator that the U.S. Army was able to defeat.) In this chapter he also shows why reusing a one time pad was not more secure than using a book as a key. If two messages are encrypted using the same key, the cryptologists, knowing this, can readily reduce the problem to the a running key using a book (text in the same language as the message.)
A note about VENONA decrypts. Though they often reused the same key, the messages themselves were coded, and then superenciphered using as “sometime” pad (as opposed to a one time pad). A coded message is “translated” into code, where the code words are arbitrary and may not even be real words. In order to decrypt the VENONA traffic the cryptologist needed to recreate the code books by inference from context, a truly daunting task.
Chapter 4 is on transposition ciphers.
I’m on Chapter 5, which covers historical topics.
Chapter 20 discusses quantum computing related to cryptography, and I look forward to reading it.
Anyway, that’s the reading assignment for this week.