A method for the tamper-proof storing of data (310, 248) in an electronic memory using a bidirectionally linked blockchain structure (100, 312) which comprises at least a first and a last block (102, 110), wherein the method comprises the steps of: • providing a bidirectionally linked blockchain structure (100, 312), • providing the data (310, 248) to be stored, • generating an additional block to extend the blockchain structure (100, 312), which block comprises the data to be stored (310, 248) and is intended to be bidirectionally linked to the last block of the blockchain structure (100, 312), wherein the last block of the blockchain structure (100, 312) comprises stored data, • calculating a first check value of the last block for bidirectionally linking the additional block to the last block of the blockchain structure (100, 312), wherein the first check value of the last block is calculated using a first hash value, the calculation of which comprises applying a hash function to the data stored in the last block and the data (310, 248) to be stored in the additional block, • calculating a check value (224, 242) of the additional block for bidirectionally linking the additional block to the last block of the blockchain structure (100, 312), wherein the check value (224, 242) of the additional block is calculated using a second hash value, the calculation of which comprises applying the hash function to the data stored in the last block and the data (310, 248) to be stored in the additional block, • adding the first check value of the last block to the last block, • adding the check value (224, 242) of the additional block to the additional block, • storing the blockchain structure (100, 312) extended by the additional block. • providing a bidirectionally linked blockchain structure (100, 312), • providing the data (310, 248) to be stored, • generating an additional block to extend the blockchain structure (100, 312), which block comprises the data to be stored (310, 248) and is intended to be bidirectionally linked to the last block of the blockchain structure (100, 312), wherein the last block of the blockchain structure (100, 312) comprises stored data, • calculating a first check value of the last block for bidirectionally linking the additional block to the last block of the blockchain structure (100, 312), wherein the first check value of the last block is calculated using a first hash value, the calculation of which comprises applying a hash function to the data stored in the last block and the data (310, 248) to be stored in the additional block, • calculating a check value (224, 242) of the additional block for bidirectionally linking the additional block to the last block of the blockchain structure (100, 312), wherein the check value (224, 242) of the additional block is calculated using a second hash value, the calculation of which comprises applying the hash function to the data stored in the last block and the data (310, 248) to be stored in the additional block, • adding the first check value of the last block to the last block, • adding the check value (224, 242) of the additional block to the additional block, • storing the blockchain structure (100, 312) extended by the additional block.