A system for tracking an asset including one or more processing devices that identify a spatial region in a complex number space, the spatial region being associated with the asset, receive a user defined password, identify a plurality of key locations within the spatial region at least in part using the user defined password, calculate key numerical values at each of the plurality of key locations using a defined complex number formula and use the key numerical values to generate an encryption key. The asset can be associated with a user by storing an asset record in a database which is indicative of an asset identifier, the spatial region and an encrypted payload derived using the encryption key.