An example operation may include one or more of receiving a new identifier from a user device associated with a user account, creating a hash based on the new identifier, comparing the hash to a hash value associated with one or more identifiers stored in a blockchain, identifying a match of the hash and the hash value associated with the one or more identifiers, authorizing the user account, responsive to identifying the match of the hash and the hash value associated with the one or more identifiers, and deleting the hash, the new identifier, and the hash value associated with the one or more identifiers stored in the blockchain responsive to authorizing the user account.