The security of data transmission across networks is paramount, where encryption poses a formidable challenge in network security. While chaos-based image encryption algorithms have garnered considerable research attention at the bit level in recent years, exploration into bit-level encryption algorithms remains limited. This paper proposes an encryption scheme based on chaotic tent mapping. Initially, a standard image is converted into two binary bit planes of identical sizes, with a permutation vector employed to nullify correlations between adjacent pixels. Through the design of diffusion strategies, the two sequences undergo mutual diffusion. Subsequently, leveraging the control afforded by tent mapping, chaotic sequences characterized by robust distribution and randomness are generated. This encryption scheme entails just one round of encryption and showcases commendable encryption performance. Simulation results and performance analysis demonstrate that this algorithm is a secure and reliable image encryption.