ctf-crypto

Name: ctf-crypto
Author: ljagiello

2.8kstars330forks

How to install ctf-crypto?

ljagiello/ctf-skills/ctf-crypto

$npx -y skills add ljagiello/ctf-skills --skill ctf-crypto

Installs into the current project.

Summary

Provides cryptography attack techniques for CTF challenges. Use when attacking encryption, hashing, signatures, ZKP, PRNG, or mathematical crypto problems involving RSA, AES, ECC, lattices, LWE, CVP, number theory, Coppersmith, Pollard, Wiener, padding oracle, GCM, key derivation

Files · 1

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SKILL.md

1	# CTF Cryptography
2
3	Quick reference for crypto CTF challenges. Each technique has a one-liner here; see supporting files for full details with code.
4
5	## Prerequisites
6
7	Python packages (all platforms):
8	```bash
9	pip install pycryptodome z3-solver sympy gmpy2 hashpumpy fpylll py_ecc
10	```
11
12	Linux (apt):
13	```bash
14	apt install hashcat sagemath
15	```
16
17	macOS (Homebrew):
18	```bash
19	brew install hashcat
20	```
21
22	Manual install:
23	- SageMath — Linux: `apt install sagemath`, macOS: `brew install --cask sage`
24	- RsaCtfTool — `git clone https://github.com/RsaCtfTool/RsaCtfTool` (automated RSA attacks)
25
26	> Note: `gmpy2` requires libgmp — Linux: `apt install libgmp-dev`, macOS: `brew install gmp`.
27
28	## Additional Resources
29
30	- [classic-ciphers.md](classic-ciphers.md) - Classic ciphers: Vigenere (+ Kasiski examination), Atbash, substitution wheels, XOR variants (+ multi-byte frequency analysis), deterministic OTP, cascade XOR, book cipher, OTP key reuse / many-time pad, variable-length homophonic substitution, grid permutation cipher keyspace reduction, image-based Caesar shift ciphers, XOR key recovery via file format headers
31	- [modern-ciphers.md](modern-ciphers.md) - Modern cipher attacks: AES (CFB-8, ECB leakage), CBC-MAC/OFB-MAC, padding oracle, S-box collisions, GF(2) elimination, LCG partial output recovery, affine cipher over composite modulus, AES-GCM with derived keys, AES-GCM nonce reuse (forbidden attack), Ascon-like reduced-round differential cryptanalysis, custom linear MAC forgery, CBC padding oracle (full block decryption), Bleichenbacher RSA PKCS#1 v1.5 padding oracle (ROBOT), birthday attack / meet-in-the-middle, CRC32 collision signature forgery, AES key recovery via byte-by-byte zeroing oracle, AES-CBC ciphertext forging via error-message decryption oracle
32	- [modern-ciphers-2.md](modern-ciphers-2.md) - Modern cipher attacks (Part 2): Blum-Goldwasser bit-extension oracle, hash length extension, compression oracle (CRIME-style), hash function time reversal via cycle detection, OFB mode invertible RNG backward decryption, weak key derivation via public key hash XOR, HMAC-CRC linearity attack, DES weak keys in OFB mode, SRP protocol bypass, modified AES S-Box brute-force, square attack on reduced-round AES, AES-ECB byte-at-a-time chosen plaintext, AES-ECB cut-and-paste block manipulation, AES-CBC IV bit-flip auth bypass, Rabin LSB parity oracle, PBKDF2 pre-hash bypass, MD5 multi-collision via fastcol
33	- [modern-ciphers-3.md](modern-ciphers-3.md) - Modern cipher attacks (Part 3): custom hash state reversal, CRC32 brute-force for small payloads, noisy RSA LSB oracle error correction, sponge hash MITM collision, CBC IV forgery + block truncation, padding oracle to CBC bitflip RCE, SPN S-box intersection attack, AES-CFB IV recovery from timestamp-seeded PRNG, three-round XOR protocol key cancellation, AES-CBC UnicodeDecodeError side-channel oracle, SHA-256 basis attack for XOR-aggregate hash bypass, custom MAC forgery via XOR block cancellation, HMAC key recovery via XOR+addition arithmetic
34	- [stream-ciphers.md](stream-ciphers.md) - Stream cipher attacks: LFSR (Berlekamp-Massey, correlation attack, known-plaintext, Galois vs Fibonacci, Galois tap recovery via autocorrelation), RC4 second-byte bias, XOR consecutive byte correlation
35	- [rsa-attacks.md](rsa-attacks.md) - RSA attacks: small e (cube root), common modulus, Wiener's, Pollard's p-1, Hastad's broadcast, Hastad with linear padding (Coppersmith), Franklin-Reiter related message (e=3), Coppersmith linearly-related primes, Fermat/consecutive primes, multi-prime, restricted-digit, Coppersmith structured primes, Manger oracle, polynomial hash
36	- [rsa-attacks-2.md](rsa-attacks-2.md) - RSA attacks (specialized): RSA p=q validation bypass, cube root CRT gcd(e,phi)>1, factoring from phi(n) multiple, multiplicative homomorphism signature forgery, weak keygen via base representation, RSA with gcd(e,phi)>1 exponent reduction, batch GCD shared prime factoring, partial key recovery from dp/dq/qinv, RSA-CRT fault attack, homomorphic decryption oracle bypass, small prime CRT decomposition, Montgomery reduction timing attack, Bleichenbacher low-exponent signature forgery, RSA signature bypass with e=1 and crafted modulus
37	- [ecc-attacks.md](ecc-attacks.md) - ECC attacks: small subgroup, invalid curve, Smart's attack (anomalous, with Sage code), fault injection, clock group DLP,

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ctf-crypto

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View on GitHub

How to install ctf-crypto?

ljagiello/ctf-skills/ctf-crypto

$npx -y skills add ljagiello/ctf-skills --skill ctf-crypto

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# CTF Cryptography
2
3	Quick reference for crypto CTF challenges. Each technique has a one-liner here; see supporting files for full details with code.
4
5	## Prerequisites
6
7	Python packages (all platforms):
8	```bash
9	pip install pycryptodome z3-solver sympy gmpy2 hashpumpy fpylll py_ecc
10	```
11
12	Linux (apt):
13	```bash
14	apt install hashcat sagemath
15	```
16
17	macOS (Homebrew):
18	```bash
19	brew install hashcat
20	```
21
22	Manual install:
23	- SageMath — Linux: `apt install sagemath`, macOS: `brew install --cask sage`
24	- RsaCtfTool — `git clone https://github.com/RsaCtfTool/RsaCtfTool` (automated RSA attacks)
25
26	> Note: `gmpy2` requires libgmp — Linux: `apt install libgmp-dev`, macOS: `brew install gmp`.
27
28	## Additional Resources
29
30	- [classic-ciphers.md](classic-ciphers.md) - Classic ciphers: Vigenere (+ Kasiski examination), Atbash, substitution wheels, XOR variants (+ multi-byte frequency analysis), deterministic OTP, cascade XOR, book cipher, OTP key reuse / many-time pad, variable-length homophonic substitution, grid permutation cipher keyspace reduction, image-based Caesar shift ciphers, XOR key recovery via file format headers
31	- [modern-ciphers.md](modern-ciphers.md) - Modern cipher attacks: AES (CFB-8, ECB leakage), CBC-MAC/OFB-MAC, padding oracle, S-box collisions, GF(2) elimination, LCG partial output recovery, affine cipher over composite modulus, AES-GCM with derived keys, AES-GCM nonce reuse (forbidden attack), Ascon-like reduced-round differential cryptanalysis, custom linear MAC forgery, CBC padding oracle (full block decryption), Bleichenbacher RSA PKCS#1 v1.5 padding oracle (ROBOT), birthday attack / meet-in-the-middle, CRC32 collision signature forgery, AES key recovery via byte-by-byte zeroing oracle, AES-CBC ciphertext forging via error-message decryption oracle
32	- [modern-ciphers-2.md](modern-ciphers-2.md) - Modern cipher attacks (Part 2): Blum-Goldwasser bit-extension oracle, hash length extension, compression oracle (CRIME-style), hash function time reversal via cycle detection, OFB mode invertible RNG backward decryption, weak key derivation via public key hash XOR, HMAC-CRC linearity attack, DES weak keys in OFB mode, SRP protocol bypass, modified AES S-Box brute-force, square attack on reduced-round AES, AES-ECB byte-at-a-time chosen plaintext, AES-ECB cut-and-paste block manipulation, AES-CBC IV bit-flip auth bypass, Rabin LSB parity oracle, PBKDF2 pre-hash bypass, MD5 multi-collision via fastcol
33	- [modern-ciphers-3.md](modern-ciphers-3.md) - Modern cipher attacks (Part 3): custom hash state reversal, CRC32 brute-force for small payloads, noisy RSA LSB oracle error correction, sponge hash MITM collision, CBC IV forgery + block truncation, padding oracle to CBC bitflip RCE, SPN S-box intersection attack, AES-CFB IV recovery from timestamp-seeded PRNG, three-round XOR protocol key cancellation, AES-CBC UnicodeDecodeError side-channel oracle, SHA-256 basis attack for XOR-aggregate hash bypass, custom MAC forgery via XOR block cancellation, HMAC key recovery via XOR+addition arithmetic
34	- [stream-ciphers.md](stream-ciphers.md) - Stream cipher attacks: LFSR (Berlekamp-Massey, correlation attack, known-plaintext, Galois vs Fibonacci, Galois tap recovery via autocorrelation), RC4 second-byte bias, XOR consecutive byte correlation
35	- [rsa-attacks.md](rsa-attacks.md) - RSA attacks: small e (cube root), common modulus, Wiener's, Pollard's p-1, Hastad's broadcast, Hastad with linear padding (Coppersmith), Franklin-Reiter related message (e=3), Coppersmith linearly-related primes, Fermat/consecutive primes, multi-prime, restricted-digit, Coppersmith structured primes, Manger oracle, polynomial hash
36	- [rsa-attacks-2.md](rsa-attacks-2.md) - RSA attacks (specialized): RSA p=q validation bypass, cube root CRT gcd(e,phi)>1, factoring from phi(n) multiple, multiplicative homomorphism signature forgery, weak keygen via base representation, RSA with gcd(e,phi)>1 exponent reduction, batch GCD shared prime factoring, partial key recovery from dp/dq/qinv, RSA-CRT fault attack, homomorphic decryption oracle bypass, small prime CRT decomposition, Montgomery reduction timing attack, Bleichenbacher low-exponent signature forgery, RSA signature bypass with e=1 and crafted modulus
37	- [ecc-attacks.md](ecc-attacks.md) - ECC attacks: small subgroup, invalid curve, Smart's attack (anomalous, with Sage code), fault injection, clock group DLP,

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