Verifolio offers certificates that are trustless and censorship-resistant. This means our certificates will always remain verifiable and can't be tampered with by any third party, including Verifolio. All this comes from the fact that they are partially stored on public blockchains. But how can a certificate stored online be private? Turns out that commitment schemes can help.
Blockchains are immutable ledger systems. This means that once an entry is recorded on the blockchain, it cannot be changed or deleted. Naturally, as ledgers are a fundamental tool in accounting, their first use case is financial transactions, which they are most known for. This entire side of blockchains does not concern us for the purpose of this article. Blockchains have other uses - for example, they can be used to store certificates, because due to their immutability, they are great sources of truth. The authenticity of the data from blockchains is already used in court cases nowadays. However, putting certificates on public blockchains faces two challenges, namely privacy and cost. Verifolio overcomes these hurdles with cryptographic techniques. Let's first review classic solutions.
Privacy can be partially tackled using symmetric cryptography. Use AES-256 encryption to encrypt the certificate and store it on the blockchain. This way, the certificate content is only known to owners of the AES secret key. However, it does not solve the problem of cost. It also introduces a lot of complexity and vulnerability with secret handling.
Costs can be tackled using cryptographic hashes, like SHA-256. Instead of storing the whole certificate content on the blockchain, store only the hash of the certificate, while the actual content is stored separately. This way, the certificate content can still be proved authentic. Surprisingly, it does not solve the problem of privacy. If a certificate content can be guessed, it can be confirmed to be correct using information from the blockchain. This is unacceptable for certificates, so Verifolio ups the game with something better.
Commitment schemes are conceptually similar to cryptographic hashes. They are also used to prove the authenticity of data using derived information of small size. The difference is that with a commitment scheme, we would like it to be impossible for other parties to guess the data before we reveal it. The name "commitment scheme" comes from analysing game theoretic concepts, but it's a powerful tool that can be used in many other contexts. Imagine someone good at cheating at rock paper scissors - they modify their choice midair depending on how their opponent plays. Commitment schemes prevent this by locking in choices, ensuring privacy until the reveal. In the same way, we give privacy to certificates stored on public blockchains. We lock in the certificate content, ensuring privacy until it's shared with others.
Commitment schemes are used in various cryptographic protocols like zero-knowledge proofs and secure computation. They have various implementations of varying sophistication that often extend the properties described above. A simple commitment scheme can be implemented using a cryptographic hash. What we need is a random cryptographic salt. We add this salt to the certificates and then compute a hash of the combined result. With the added random portion, the content of the certificate is no longer guessable, and hence the hash can no longer be used to figure out the content. This trick amends a critical weakness of cryptographic hashes for the purpose of storing certificates on public blockchains.
At Verifolio, we utilize the power of commitment schemes to deliver certificates that are private, authentic, and affordable, all while leveraging the unmatched security of public blockchains. By storing only a cryptographic commitment on-chain, we ensure your sensitive documents remain confidential yet verifiable, giving you the ability to own and share certificates without compromising privacy. Whether you’re a professional showcasing qualifications or an organization verifying records, you can leverage Verifolio’s focus on building trust in the digital age. Join us in building a future where your certificates are secure, portable, and truly yours.