Top Ten Best Cryptography SitesThis is a list of best sites to learn cryptography from beginner to expert.
Learn Cryptography is a resource for understanding how and why the cryptographic systems you use every day work to secure your communications and protect your privacy.
This is the best resource ever. The description of complex concepts is simplified to the very basics, making it the first place to look for cryptography-related questions and solutions. The presentation layout is also very conducive to learning and very effective.
CryptoLab provides a suite of 20+ cryptography-related tools for a broad selection of ciphers - from classical (Caesar, Vigenère, etc.) to modern (RC4, DES, and RSA). It can be used to practice encryption and decryption using various techniques, and even to view the real-time intermediate steps for advanced ciphers like RC4 and DES modes.
The Code Book is a history of cryptography, all the way from Caesar shift ciphers to quantum cryptography. It is engaging and accessible, even to those with minimal skills in mathematics.
The best part of The Code Book is its Cipher Challenge: a series of ten encrypted texts using ciphers from the book.
I would strongly recommend getting the texts from the website. There is nothing more frustrating than being stymied by one of the challenges only to find that you've transcribed the text incorrectly. I would also recommend skipping the Beale/book cipher - Challenge 5 - as it is extremely difficult to crack.
If you are looking for further cryptological practice, check out the National Cipher Challenge:
Challenges on this site provide puzzles on crypto and it is one of the best sites to practice cryptography. Each puzzle tries to cover a special cipher algorithm or method. Besides challenges, there are some game puzzles like MortalCoil and Runway Robot, which are good for your brain when you are bored.
This site will host all eight sets of our crypto challenges, with solutions in most mainstream languages.
Crack ciphers, discover secrets, and improve your math skills! Games, challenges, and tools are available to make and break secret codes. Encrypt and decrypt your own messages or try ours.
Learn by doing. Learn how to exploit common cryptographic flaws, armed with nothing but a little time and your favorite programming language. Forge administrator cookies, recover passwords, and even backdoor your own random number generator.