The present disclosure relates to secure and verifiable storage and retrieval of data, in particular in the context of product tracking. According to one aspect there is provided a computer-implemented verifiable data storage method comprising: receiving a product serial number; receiving an account identifier; producing a non-invertible hash by operating on the product serial number and the account identifier; and causing the hash to be written to a secure distributed data store. According to another aspect there is provided a computer-implemented verification method comprising: receiving a product serial number; receiving an account identifier; producing a non-invertible hash by operating on the product serial number and the account identifier; searching a secure distributed data store for the hash; and depending on a result of the searching, providing confirmation or denial of the hash's presence in the secure distributed data store.