A secure storage device with the external dimensions of a PCMCIA card, for securing digital camera data at the acquisition stage. Original digital camera data is saved in the memory of the secure storage device which has the capability of performing one or more security functions, including encryption, creation of an authentication file, adding data to the image data such as fingerprinting, and adding secure annotations such as separate data included in an image-header. The device prepares original authentication data from original digital camera data, and encrypts and stores both the original authentication data and the original image data. The use of the device includes downloading the original image data to a first computer, and encrypted original authentication data to a second computer. The second computer can be programmed with software whereby the encrypted original authentication data can be decrypted by a user having a key. The software then allows the user to prepare corresponding second authentication data from second image data of questionable authenticity. If the second authentication data is the same as the original authentication data, the questionable second image data is deemed to be an accurate copy of the original image data.