| The emergence of public cloud storage server has solved rapid expansion of data management costs due to the diversification of information. At the same time, frequent public cloud server data breaches warn us that although cloud server provides the convenience for data storage, it caused considerable security risks in recent years. This paper uses file splitting to disperse the overall information of the target file,making sure users have the original document of self-management, thereby to protect data privacy security. The study of encrypted splitting images has realistic meaning and practical value.Considering the major data transmission formats of today, the study focuses on images and aims to enhance the security of the images on public cloud storage servers. Firstly, a chaos encryption algorithm is built on iOS, which shifts the pixel gray value of images to hide away their original information and disorganize the relevance of the pixels, so that it's no longer possible to reconstruct the images from the adjacent pixels' relevance or the overall gray level distribution of the image. Pretreatment of the image is thus accomplished. Next, on the file level, generate a random sequence with random function, and using that random sequence, split the original file into cryptograph and keys. With part of the original file as the keys, its information integrity is compromised and its safety secured. Lastly, a cloud storage server and a private server are built and connected with the client respectively. The keys and cryptograph will then be uploaded to the two servers to finish the encryption process.Tests of the whole encryption process shows that the step to spilt the file takes less than 1% of the time in the process, adding almost no time complexity to the chaos encryption algorithm; the original image's information is successfully hide away by the encryption, and the encrypted images can withstand the common decoding methods. Expected objective is reached. |
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