Cryptopals

These are my solutions to the original 6 sets of Cryptopals crypto challenges (also called the Matasano challenges). These solutions are written in Python 3.

Set 1: Basics

• 01. Convert hex to base64
• 02. Fixed XOR
• 03. Single-byte XOR cipher
• 04. Detect single-character XOR
• 05. Implement repeating-key XOR
• 06. Break repeating-key XOR
• 07. AES in ECB mode
• 08. Detect AES in ECB mode

Set 2: Block Crypto

• 09. Implement PKCS#7 padding
• 10. Implement CBC mode
• 11. An ECB/CBC detection oracle
• 12. Byte-at-a-time ECB decryption (Simple)
• 13. ECB cut-and-paste
• 14. Byte-at-a-time ECB decryption (Harder)
• 15. PKCS#7 padding validation
• 16. CBC bitflipping attacks

Set 3: Block & Stream Crypto

• 17. The CBC padding oracle
• 18. Implement CTR, the stream cipher mode
• 19. Break fixed-nonce CTR mode using substitions
• 20. Break fixed-nonce CTR statistically
• 21. Implement the MT19937 Mersenne Twister RNG
• 22. Crack an MT19937 seed
• 23. Clone an MT19937 RNG from its output
• 24. Create the MT19937 stream cipher and break it

Set 4: Stream Crypto & Randomness

• 25. Break "random access read/write" AES CTR
• 26. CTR bitflipping
• 27. Recover the key from CBC with IV=Key
• 28. Implement a SHA-1 keyed MAC
• 29. Break a SHA-1 keyed MAC using length extension
• 30. Break an MD4 keyed MAC using length extension
• 31. Implement and break HMAC-SHA1 with an artificial timing leak
• 32. Break HMAC-SHA1 with a slightly less artificial timing leak

Set 5: Diffie-Hellman and Friends

• 33. Implement Diffie-Hellman
• 34. Implement a MITM key-fixing attack on Diffie-Hellman with parameter injection
• 35. Implement DH with negotiated groups, and break with malicious "g" parameters
• 36. Implement Secure Remote Password (SRP)
• 37. Break SRP with a zero key
• 38. Offline dictionary attack on simplified SRP
• 39. Implement RSA
• 40. Implement an E=3 RSA Broadcast attack

Set 6: RSA and DSA

• 41. Implement unpadded message recovery oracle
• 42. Bleichenbacher's e=3 RSA Attack
• 43. DSA key recovery from nonce
• 44. DSA nonce recovery from repeated nonce
• 45. DSA parameter tampering
• 46. RSA parity oracle
• 47. Bleichenbacher's PKCS 1.5 Padding Oracle (Simple Case)
• 48. Bleichenbacher's PKCS 1.5 Padding Oracle (Complete Case)

Still to come

• Refactoring of solutions to Sets 1-6
• Solutions to Sets 7 and 8 (beyond the "original" challenges)