Here's the ultimate guide to all the amazing cryptography resources!

I have the links that were the most helpful for me last season in bold. However, don’t underestimate the other ones! There’s a lot left out there that I haven’t yet made much use of.

Your Bread and Butter (The Holy Grail)

https://cryptograms.puzzlebaron.com/ - an online source for basic aristocrats; don’t underestimate how much this website can help you (it’s basically all I did last season)

• Create an account and hit the “play” option to participate in the monthly competitions for accuracy, speed, or total points.

By the National Supervisors

https://toebes.com/codebusters/index.html - all the practice tests you could ever want. You can also create your own tests or look at step-by-step walkthroughs on some of the sample questions. John Toebes is also a pretty nice guy, and if you want to win him over just mention that you’ve used his website before.

• https://toebes.com/codebusters/TestGuidance.html - When making a test, be sure to make good use of this guide. It also gives you a sense of the point value spread you’ll need to get used to in order to find out which ciphers you’ll prioritize.

http://www.gregorybard.com/cryptogram.html - has a good amount of information to digest and goes very in-depth with different helpful links, books, and various examples waiting for you at the bottom of the page. Unlike John Toebes, this guy is a weirdo. Do not talk to him about zebra skeletons.

General

https://scioly.org/wiki/index.php/Codebusters - a good introduction to the different cipher types and strategies 

https://docs.google.com/document/d/1orxg1_WwpUYa33pdfXweEYa9mmm0SSo73XAHUWP3fdk/edit?usp=sharing - common word patterns! 

For Studying

http://practicalcryptography.com/ - has good readings and practice for many ciphers; peruse the entirety of website as this link will really help you become more knowledgeable and competitive

https://crypto.interactive-maths.com/ - Practical Cryptography and Crypto Corner are the most helpful study links I came across last year

Frequencies

https://www3.nd.edu/~busiforc/handouts/cryptography/cryptography%20hints.html - basic frequencies

http://practicalcryptography.com/cryptanalysis/letter-frequencies-various-languages/english-letter-frequencies/ - English letter/n-gram frequencies

http://practicalcryptography.com/cryptanalysis/letter-frequencies-various-languages/spanish-letter-frequencies/ - Spanish letter/n-gram frequencies

https://www.wordfrequency.info/free.asp?s=y - don’t get too overwhelmed

https://www.vistawide.com/spanish/top_100_spanish_words.htm - same deal in Spanish

Further Reading

https://math.ucsd.edu/~crypto/java/EARLYCIPHERS/Monoalphabetic.html - plaintext attack (monosubs)

https://www.khanacademy.org/computing/computer-science/cryptography - use this entire playlist (even what seems unneeded). It’ll help you later on with the mathematical side of Code (especially Hill and RSA)

Cipher Specific

Vigenere:

http://www.martani.net/2011/04/cracking-vigenere.html 

https://pages.mtu.edu/~shene/NSF-4/Tutorial/VIG/Vig-Kasiski.html

• Both dedicated to solving Vigenere ciphers without a given key (the most popular technique being Kasiski’s Method)

Pollux/Morbit: 

Fractionating Ciphers - Crypto Corner

fractionated morse cipher

Morbit Cipher - Decoder, Encoder, Solver, Translator

RSA: (use the Khan Academy videos provided above first for a better understanding)

https://brilliant.org/wiki/rsa-encryption/ (explanation)

https://people.csail.mit.edu/rivest/RivestKaliski-RSAProblem.pdf (reading)

https://www.cs.drexel.edu/~jpopyack/IntroCS/HW/RSAWorksheet.html (tutorial and calculator)

https://www.cs.drexel.edu/~introcs/Fa11/notes/10.1_Cryptography/RSA_Express_EncryptDecrypt.html (calculator)

Tools

http://www.cryptogram.org/ - not to be confused with the first link way up there. Under the “Resources” tab you will find a cipher solver when you are stuck, explanations of various ciphers (way more than you’ll ever need to understand), and word lists in a ton of languages.

https://www.dcode.fr/en - decoder

https://cryptii.com/ - decoder with a cleaner user interface

http://rumkin.com/tools/cipher/substitution.php - substitution encoder

https://www.cryptoclub.org/ - interactive learning through games