Novel Encryption Method of GPS Information in Image File Using Format-Preserving Encryption.

Global Positioning System (GPS) information is stored in EXchangeable Image File Format (EXIF) in the image file. It is considered personal information; therefore, sharing it without the owner's consent could lead to personal information disclosure. GPS information is embedded on the images uploaded by many people on social network services or stored in the Cloud. Images must be encrypted to prevent GPS information from being disclosed. However, there are no existing methods to encrypt them in EXIF. Using block cipher for encryption can exceed the tag value range of EXIF. In this paper, we propose a method to encrypt the GPS information of an image file using Format-Preserving Encryption, which preserves the length and format of the plaintext. We confirmed that GPS information can be secured by encrypting it in image files.