Abstract: There is provided herein a disrupted block chain cryptocurrency system for securement against unauthorised transactions from the theft of private keys wherein the mining computing devices thereof comprise transaction pre-processors which, for each cryptocurrency transaction received, identifies an address associated with the cryptocurrency transaction and searches the block chain ledger for at least one previous cryptocurrency transaction of a specific format associated with the address. If such a transaction is found, the transaction is held in a memory pool for security as opposed to adding to a block for hashing and a further address is identified from the at least one previous transaction. The transaction is held in the memory pool until a further cryptocurrency transaction from the further address is pre-processed which comprises meta data identifying a transaction ID of the transaction stored within the memory pool for removal and adding to a block for hashing.