go-cryptopals

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go-cryptopals

My solutions to the Cryptopals cryptography challenges 🔒 in well^{[citation needed]} commented Golang.

A lot of things are implemented from scratch for lolz: hex, base64, AES with various modes (plain, ECB, CBC, CTR), SHA-1, SHA-256, MD4, HMAC-SHA1, HMAC-SHA256.

A branch implements bigints from scratch but is currently too slow to be used to solve all the challenges.

The references folder contains a copy of various whitepapers and RFCs useful for solving these challenges.

I have solved sets 1 through 7. I hope to finish the final set 8 soon 🤞.

Set 1

• Convert hex to base64
• Fixed XOR
• Single-byte XOR cipher
• Detect single-character XOR
• Implement repeating-key XOR
• Break repeating-key XOR
• AES in ECB mode
• Detect AES in ECB mode

Set 2

• Implement PKCS#7 padding
• Implement CBC mode
• An ECB/CBC detection oracle
• Byte-at-a-time ECB decryption (Simple)
• ECB cut-and-paste
• Byte-at-a-time ECB decryption (Harder)
• PKCS#7 padding validation
• CBC bitflipping attacks

Set 3

• The CBC padding oracle
• Implement CTR, the stream cipher mode
• Break fixed-nonce CTR mode using substitutions
• Break fixed-nonce CTR statistically
• Implement the MT19937 Mersenne Twister RNG
• Crack an MT19937 seed
• Clone an MT19937 RNG from its output
• Create the MT19937 stream cipher and break it

Set 4

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

Set 5

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

Set 6

• Implement unpadded message recovery oracle
• Bleichenbacher's e=3 RSA Attack
• DSA key recovery from nonce
• DSA nonce recovery from repeated nonce
• DSA parameter tampering
• RSA parity oracle
• Bleichenbacher's PKCS 1.5 Padding Oracle (Simple Case)
• Bleichenbacher's PKCS 1.5 Padding Oracle (Complete Case)

Set 7

• CBC-MAC Message Forgery
• Hashing with CBC-MAC
• Compression Ratio Side-Channel Attacks
• Iterated Hash Function Multicollisions
• Kelsey and Schneier's Expandable Messages
• Kelsey and Kohno's Nostradamus Attack
• MD4 Collisions
• RC4 Single-Byte Biases

Set 8

• Diffie-Hellman Revisited: Small Subgroup Confinement
• Pollard's Method for Catching Kangaroos
• Elliptic Curve Diffie-Hellman and Invalid-Curve Attacks
• Single-Coordinate Ladders and Insecure Twists
• Duplicate-Signature Key Selection in ECDSA (and RSA)
• Key-Recovery Attacks on ECDSA with Biased Nonces
• Key-Recovery Attacks on GCM with Repeated Nonces
• Key-Recovery Attacks on GCM with a Truncated MAC
• Truncated-MAC GCM Revisited: Improving the Key-Recovery Attack via Ciphertext Length Extension
• Exploiting Implementation Errors in Diffie-Hellman

Set 9

I found an unofficial set 9 by Andrei Ilchenko.