Rhysida's time-seeded PRNG cracked: attacker's own ciphertext yields a decryptor
Rhysida's Windows encryptor seeds its PRNG with srand(time(0)), so every per-file AES-256 key and IV in a run derives from one 32-bit timestamp. This signed preprint exploits that: the RSA-OAEP blob appended to each encrypted file acts as a validation oracle, letting you confirm candidate seeds by replaying the encryptor's own RSA step, with no plaintext needed. Seventeen variants carry the flaw; the recovery costs one RSA operation per candidate second.