Chaos-based encryption provides a practical way to protect the confidentiality of digital images nowadays. The increasing convenience (e.g., larger bandwidth) of data sharing stimulates the need for encrypting amounts of images in a fast manner. Yet most existing works aim to encrypt an image for each time. Although some parallel encryptions have been proposed, the speed is still far from satisfactory to proceed with the huge increasing number of images. This inspires us to consider another promising way, encrypting a batch of images parallelly for each time. We use maximum available number of threads in parallel computation for full use of processor resources. Considering the batch images as a shared resource, every thread competes with others to encrypt images in the shared resource in a preemptive manner for encryption. A classical permutation-diffusion architecture for chaos-based encryption is utilized for each thread, where logistic map and Lorenz system are used for generating keystream for permutation and diffusion, respectively. We make cryptographical analyses and perform experiments to confirm that the security is guaranteed. The results of efficiency tests demonstrate that the encryption speed is greatly improved compared with the state-of-art image encryption algorithms in parallel as well as serial modes.

基于混沌的加密为当今保护数字图像的机密性提供了一种实用的方法。越来越多的便利（例如，更大的带宽）的数据共享激发了对快速加密图像数量的需求。然而，大多数现有作品旨在每次都对图像进行加密。尽管已经提出了一些并行加密，但是对于大量增加的图像，速度仍然远远不能令人满意。这激发了我们考虑另一种有前途的方法，每次都并行加密一批图像。为了充分利用处理器资源，我们在并行计算中使用最大可用线程数。将批处理映像视为共享资源，每个线程都与其他线程竞争以抢先方式对共享资源中的映像进行加密。每个线程都采用了经典的置换扩散架构，用于基于混沌的加密，其中逻辑地图和Lorenz系统分别用于生成置换和扩散的密钥流。我们进行密码分析并进行实验以确认安全性。效率测试的结果表明，与并行和串行模式下的最新图像加密算法相比，加密速度大大提高。