Some Crypto CTF Challenges I solved as part of a course on Public Key Cryptography at TU Berlin, with extensive write-ups.
Topic: Chinese Remainder Theorem
Status: Flag captured
Topic: Addition Chains for faster modular exponentiation
Status: Flag captured
Topic: RSA with optimized decryption using Chinese Remainder Theorem
Status: Flag captured
Topic: Hastad Broadcast Attack on RSA
Status: Flag captured
Topic: GENERALIZED Hastad Broadcast Attack on RSA
Status: solved for own example, but flag not captured
Topic: Breaking a number of (trivial) padding schemes (in RSA)
Status: Flag captured
Topic: Common Modulus Attack on RSA
Status: Flag captured
Topic: Wiener's attack on small private RSA exponent, factoring RSA modulus using the private exponent d
Status: Flag captured
Topic: RSA signature forgery (small public exponent)
Status: Flag captured
Topic: RSA signature forgery (signature oracle)
Status: Flag captured
Topic: Factoring RSA modulus (using Fermat factorization)
Status: Flag captured
Topic: Discrete Log in the Symmetric Group (group-based crypto, Diffie-Hellman)
Status: some tricky detail keeping me from capturing the flag >:(