A decryption system for decrypting user identification information encrypted on a storage device associated with a user identity document is disclosed. The system comprises: a server configured to collect user identity document data from the user and to construct a token including the user identity document data encoded in a machine readable form; a key construction unit communicatively coupled to a reader configured to read the data from the token and configured to read the data encoded on the storage device. The key construction unit uses the user identity document data read from the token to construct a key which enables the identity document reader to decrypt the user identification information stored on the storage device.