An item open registry and authentication system comprising: one or more physical items each having an identity tag coupled to the item, the identity tags each storing a private key and a unique identifier and configured to enable the unique identifier to be wirelessly read but prevent the private key from being read from the tag; a mobile device configured to wirelessly read the unique identifier from one or more of the identity tags when proximate to the one or more of the tags; and an open registry storing the unique identifier, item information and a public key of each of the physical items, wherein the public key is associated with the private key stored on the identity tag coupled to the physical item, wherein the open registry is a blockchain and the item information includes a chain of ownership that defines a sequence of owners of the physical item and a sequence of transactions between pairs of the owners that conferred the ownership of the physical item between the pairs of the owners, the open registry being operable to; register the unique identifier and the public key of the item as an identifier/key pair; upload and associate each of one or more restricted-access websites with the identifier/key pair of the public key and the unique identifier; provide access to the public key and the unique identifier; and provide a private uploading option which when selected displays the public key and the unique identifier without presenting associated data identifying a source of the unique identifier and the public key; wherein the mobile device is configured to include an identity verification function that, upon reading the unique identifier of the identity tag of one of the physical items, causes the mobile device to: generate and transmit a challenge message to the identity tag; transmit the unique identifier to the open registry and access the public key associated with the unique identifier from the open registry; receive a digital signature from the identity tag; authenticate the item by determining if the digital signature was generated by the private key stored in the identity tag using the accessed public key; and if the physical item is authenticated, automatically access and present a network accessible location to a user on the mobile device, wherein the network accessible location is a website related to the item including information about the physical item. one or more physical items each having an identity tag coupled to the item, the identity tags each storing a private key and a unique identifier and configured to enable the unique identifier to be wirelessly read but prevent the private key from being read from the tag; a mobile device configured to wirelessly read the unique identifier from one or more of the identity tags when proximate to the one or more of the tags; and an open registry storing the unique identifier, item information and a public key of each of the physical items, wherein the public key is associated with the private key stored on the identity tag coupled to the physical item, wherein the open registry is a blockchain and the item information includes a chain of ownership that defines a sequence of owners of the physical item and a sequence of transactions between pairs of the owners that conferred the ownership of the physical item between the pairs of the owners, the open registry being operable to; register the unique identifier and the public key of the item as an identifier/key pair; upload and associate each of one or more restricted-access websites with the identifier/key pair of the public key and the unique identifier; provide access to the public key and the unique identifier; and provide a private uploading option which when selected displays the public key and the unique identifier without presenting associated data identifying a source of the unique identifier and the public key; wherein the mobile device is configured to include an identity verification function that, upon reading the unique identifier of the identity tag of one of the physical items, causes the mobile device to: generate and transmit a challenge message to the identity tag; transmit the unique identifier to the open registry and access the public key associated with the unique identifier from the open registry; receive a digital signature from the identity tag; authenticate the item by determining if the digital signature was generated by the private key stored in the identity tag using the accessed public key; and if the physical item is authenticated, automatically access and present a network generate and transmit a challenge message to the identity tag; transmit the unique identifier to the open registry and access the public key associated with the unique identifier from the open registry; receive a digital signature from the identity tag; authenticate the item by determining if the digital signature was generated by the private key stored in the identity tag using the accessed public key; and if the physical item is authenticated, automatically access and present a network accessible location to a user on the mobile device, wherein the network accessible location is a website related to the item including information about the physical item.