15. A decryption system for decrypting user information encrypted on a storage device associated with an identity document of a user, the system comprising: a server configured to collect user identity document data and user identification information from the user and to construct a token comprising the user identity document data, wherein the server is further configured to send the token to a mobile device associated with the user for storing the token at the mobile device and wherein the mobile device is physically separate from said storage device; a machine reader configured to read the data from the token by radio frequency identification communication with the mobile device, wherein the reader uses the user identity document data read from the token, stored on the mobile device, to decrypt the user information stored on said storage device; a comparator for comparing the data read from the token stored on the mobile device and the user information decrypted from said storage device associated with the user identity document; and authentication means for authenticating the user depending upon the result of the comparison.
15. A decryption system for decrypting user information encrypted on a storage device associated with an identity document of a user, the system comprising: a server configured to collect user identity document data and user identification information from the user and to construct a token comprising the user identity document data, wherein the server is further configured to send the token to a mobile device associated with the user for storing the token at the mobile device and wherein the mobile device is physically separate from said storage device; a machine reader configured to read the data from the token by radio frequency identification communication with the mobile device, wherein the reader uses the user identity document data read from the token, stored on the mobile device, to decrypt the user information stored on said storage device; a comparator for comparing the data read from the token stored on the mobile device and the user information decrypted from said storage device associated with the user identity document; and authentication means for authenticating the user depending upon the result of the comparison. 16. A decryption system according to claim 15 wherein the reader is a portable reader or scanner or a mobile telephone.