Learn about cryptography through the Proof of Existence (PoE) feature of the Bitcoin blockchain

Proof of Existence (PoE) is a feature built into the Bitcoin blockchain that allows anyone to store records in an immutable manner.

Storing records on the Bitcoin blockchain

Records stored on the blockchain may not be legally binding at the moment, but they may be in the near future. For example, the US state of Arizona has approved a bill recognizing blockchain-based contracts as legally binding. Even so, using a distributed database like the blockchain to protect specific data will ensure that your records are cemented in the history books. These records can include documents such as wills, land titles, digital copyrights, and more. Storing your records digitally on the Bitcoin blockchain requires some practice that anyone can accomplish.

RSA encryption, message digests, and Bitcoin public chain

The best way to create storage files that remain private on a public blockchain is to encrypt the data. The first thing to do is to create some public and private keys using your computer. Linux and Mac OS users can generate these keys using a program like sshkeygen, while Windows users can use a software called Puttygen.

Public key or asymmetric cryptography uses mathematical keys to allow for encryption and decryption protocols. With Puttygen, users simply launch the program and click "generate RSA keys," enter a unique key password, and then save the newly created public and private keys.

Use Puttygen to save private and public keys

Once you have received the key pair, the next step is to create a message digest, where you add a hash function to the file, record, or text. Message digest software can be downloaded online and can calculate a range of different encryption algorithms, such as MD2, MD4, MD5, and SHA-256. By creating this message digest, this will create a unique input for the data you recorded. Following this step, you can encrypt the message using your newly created private key and add your digital signature to the message. There are a few different ways to provide data for blockchain proof of existence (PoE). For example, software developer Chris Ellis explains on Github how to create a world citizen certificate through an XML or JSON document that uses digital signatures and blockchain.

Bind your private key to the message digest

Finally, if you want to tie this signed message digest to your document and add it to the Bitcoin blockchain. Then you have to remember that the Bitcoin blockchain can be used to hash this message digest string into a transaction, which is different from "attaching" the document to the blockchain. The document is not stored there, but only the key or string of numbers is connected to the transaction and recorded on the public chain. Essentially this is a digital signed "representation" of your document. Many other messages on the blockchain are hexadecimal codes, such as the Satoshi genesis block text. These specific kinds of blockchain messages are created by using 100 bytes of arbitrary text in the coinbase.

The Massachusetts Institute of Technology (MIT) is also working on a PoE certificate project that can record students' academic qualifications on the blockchain. However, when using these services, you have to remember that you need to trust the integrity of the data to a third party because they are the ones who record your academic information on the blockchain.

The Bitcoin blockchain hosts a vast array of hexadecimal propaganda texts, including a tribute to Nels Mandela, the Satoshi Nakamoto creation message, Wikileaks secrets and thousands of others. In addition, people have used the Bitcoin blockchain to record birth certificates, create global passports and marriage certificates.

Satoshi Nakamoto information found in the Genesis block

Prove ownership and learn cryptography

Proving digital ownership of a document is a great way to use the Proof of Existence (PoE) feature of the Bitcoin blockchain. The Bitcoin blockchain also timestamps transactions as soon as they are processed. This means that data is securely registered on a globally distributed network, allowing users to prove ownership at any time in the future through this digital signature. Because this eliminates the need for some third-party institutions in the future, this use case of the Bitcoin blockchain may affect the legal system, law firms, notary services, and more. Learning how to create private/public keys and apply secure documents to the powerful Bitcoin blockchain will make our crypto technology field fascinating.