This paper presents a simplified Attribute-Based Signature (ABS) scheme leveraging the RSA cryptosystem. In this scheme, users sign messages based on their possession of specific attributes, where each attribute is linked to a unique RSA key pair. The signing process ensures that users can only generate valid signatures if their attribute set satisfies the required policy. The verification algorithm verifies the signature’s legitimacy using the public keys corresponding to the required attributes, while maintaining the security guarantees of RSA. We provide a correctness proof demonstrating that any valid signature generated using the signing algorithm will be accepted by the verifier. Furthermore, we prove the unforgeability of the scheme under the RSA assumption, showing that an adversary cannot forge a signature without possessing the appropriate private keys corresponding to the attributes specified in the policy. This simplified ABS scheme provides a basic framework for attribute-based cryptographic protocols using RSA, offering security guarantees grounded in the computational hardness of the RSA problem.