Blockchains do not require huge peer-to-peer networks to become secure and useful. With the new technology of the Back-Step Blockchain it is possible to create reliable chains where you can easily proof that the integrity of the chain is untampered. These are the prerequisites to enable personal chains for each one of us. As we have personal databases and personal files already. The difference is that the blocks cannot be altered and external parties can trust your data. We show here how this works.
The new technology with the Back-Step Blockchain is the value that runs from the future to the past. This value is calculated in Hardware and is unique for each chain. Different to the cryptocurrencies where you need thousands of identical chains spread over the internet, your chain is unique.

The unique back-step value travels all the way to your first block in your chain. This first block is called the genesis block. It has no predecessor and the field for the previous hash is therefore empty, normally filled with 0’s. We are different, we take the first back-step value and make one additional one-way operation and fold the result back and use it in the genesis block instead of filling with 0’s.

How do you know that the chain is yours? If the payload of the first record(s) contains your digital identity in the form of a certificate, which describes you and if this certificate is signed by a trusted authority, then you can use that blockchain like your credit card.

For the engineers among the readers, there are two minor things to know. The own certificate has a related private key, which is kept secret in a hardware chip. To proof to externals, that its your chain, they can encrypt a random number with your public key, send it to you. After its placed into your chain the back-step hardware decrypts the number and places it in the next block. Now you have 2 blocks, one with the challenge (encrypted) and one with the decrypted result. The external party can now see this two blocks, verify that the random number is correctly decrypted and calculate the back-step value from the current block back to the previous one. This also proves that you are in possession of the physical back-step generator.

This article shall inspire the creativity of application developers and open for them a completely new area of opportunities.

The two diagrams visualize a standard back-step chain and a chain with fold-back and identity block.

Figure 1: Begin of a chain with genesis block

Figure 2: Begin of chain with one-way fold back and identity in the genesis block