Smart Grid (SG) has gain popularity due to reliability, efficiency, and sustainability. They transmit periodically collected reading. The reading contains very sensitive data such as personal information and geometric locations. Therefore, transmission and storage of data have many security challenges such as eavesdropping and tampering attacks. This proposes a novel authentication encryption scheme that provides confidentiality, integrity, and authentication of the data. To achieve these objectives, we have hybrid the LEOPARD and chaotic tent map algorithm. The LEOPARD algorithm provides confidentiality and the chaotic tent map algorithm gives the authentication tag to verify the data integrity and authentication. The algorithm is simulated in MATLAB. The experimental results show that the proposed algorithm provides better results as compared to the existing algorithms in terms of PSNR, execution time, and security.