RSA Factorisation

RootMe Challenge: Decrypt the password : The validation password was encrypted using this public key.

ciphertext :

e8oQDihsmkvjT3sZe+EE8lwNvBEsFegYF6+OOFOiR6gMtMZxxba/bIgLUD8pV3yEf0gOOfHuB5bC3vQmo7bE4PcIKfpFGZBA

1. Decode the base64 ciphertext

2. Use RsaCtfTool

3. Decrypt message with openssl

Resources

• Cryptanalysis of short RSA secret exponents

• DROWN: Breaking TLS using SSLv2

• Chosen ciphertext attacks against protocols based on the RSA encryption standard - Daniel Bleichenbacher

• Continued Fractions