This document proposes a key-aggregate encryption scheme called Input Cumulative Cryptosystem for secure and scalable data sharing in cloud computing. The scheme allows a data owner to generate a constant-size aggregate decryption key that can decrypt multiple ciphertexts. The key has the combined decryption power of all individual secret keys. An intrusion detection system also monitors communication between hosts to only allow data sharing between trusted hosts, improving security. The proposed system aims to address issues with existing approaches that require distributing multiple decryption keys or have fixed hierarchies for access control. It allows flexible delegation of decryption rights for dynamic sets of ciphertexts in cloud storage.