**Abstract**

Cryptography is the science that concerns protecting information by transforming its comprehensible form into an incomprehensible one. The conception of a robust cryptosystem is a challenge. In this paper, an improved hybrid cryptosystem for numerical image protection is presented. First, the initial secret key is generated by a secure hash function (keccak). Secondly, the plain image is encrypted through the advanced encryption standard (AES) with CTR mode. Finally, a Rivest-Shamir-Adleman (RSA) algorithm is used to secure the symmetric key transmitted over the insecure channel and owner signature. Our cryptosystem is implemented in hardware and evaluated by different tools mainly identified from the image cryptography community using numerous kinds of standard images. The experimental and analytical findings prove that our framework security gives a trade-off between robustness and performance, which can be used in several domains like medicine, military, and community privacy.

**Keywords:** hybrid scheme, encryption/decryption, signature/verification
