Cracking Codes with Python

Learn how to program in Python while making and breaking ciphers-algorithms used to create and send secret messages! After a crash course in Python programming basics, you'll learn to make, test, and hack programs that encrypt text with classical ciphers like the transposition cipher and Vigenère cipher. You'll begin with simple programs for the reverse and Caesar ciphers and then work your way up to public key cryptography, the type of encryption used to secure today's online transactions, including digital signatures, email, and Bitcoin.Each program includes the full code and a line-by-line explanation of how things work. By the end of the book, you'll have learned how to code in Python and you'll have the clever programs to prove it!You'll also learn how to:- Combine loops, variables, and flow control statements into real working programs- Use dictionary files to instantly detect whether decrypted messages are valid English or gibberish- Create test programs to make sure that your code encrypts and decrypts correctly- Code (and hack!) a working example of the affine cipher, which uses modular arithmetic to encrypt a message- Break ciphers with techniques such as brute-force and frequency analysisThere's no better way to learn to code than to play with real programs. Cracking Codes with Python makes the learning fun!

IntroductionChapter 1: Making Paper Cryptography ToolsChapter 2: Installing PythonChapter 3: The Interactive ShellChapter 4: Strings and Writing ProgramsChapter 5: The Reverse CipherChapter 6: The Caesar CipherChapter 7: Hacking the Caesar Cipher with the Brute-Force TechniqueChapter 8: Encrypting with the Transposition CipherChapter 9: Decrypting with the Transposition CipherChapter 10: Programming a Program to Test Our ProgramChapter 11: Encrypting and Decrypting FilesChapter 12: Detecting English ProgrammaticallyChapter 13: Hacking the Transposition CipherChapter 14: Making a Modular Arithmetic Module for the Multiplicative and Affine CiphersChapter 15: Programming the Affine CipherChapter 16: Hacking the Affine CipherChapter 17: The Simple Substitution CipherChapter 18: Hacking the Simple Substitution CipherChapter 19: The Vigenere CipherChapter 20: Frequency AnalysisChapter 21: Hacking the Viginere CipherChapter 22: The One-Time Pad CipherChapter 23: Finding Prime NumbersChapter 24: Generating Keys for the RSA CipherChapter 25: Public Key Cryptography and Programming the RSA CipherAppendix: Debugger