Memperkuat File to Image Encryption Terhadap Known Plaintext Attack Menggunakan Blum Blum Shub Generator dan 2D Arnold's Cat Map

File to Image Encryption (FTIE) is a method for encrypting plainfile (plaintext in the form of a file) into cipherimage. This method is weak against known plaintext attack (KPA) because by exploiting the encryption-decryption equation in Randomized Text encryption (RT), the attacker may obtain the key with the time complexity of O(n_p). This research is proposed to strengthen the security of the keystream on FTIE by implementing Blum-Blum-Shub pseudo-random number generator (BBS) and two-dimensional Arnold's Cat Map (2D ACM). BBS is cryptographically secure to produce a keystream, where the algorithm to attack BBS is categorized as one of NP-complete problem. Implementing 2D ACM is highly reduce the encryption and decryption execution time, and it is also a strong matrix transposition by using a proper parameters. Our experiments and theoretical analyses prove that the proposed method is secure against KPA and the execution time is faster than the previous method.