Electronic signature with blockchain verification
Every document signed in Validocus is anchored on the Avalanche blockchain by its SHA-256 hash. Immutable, publicly verifiable, with cryptographic proof of existence, integrity, and authorship.
What is a blockchain signature?
A blockchain signature is a technique that combines a traditional electronic signature with the publication of the document's cryptographic hash on a public blockchain. When you sign a PDF in Validocus, the platform computes a unique 256-bit identifier (the SHA-256 hash) that is mathematically impossible to reproduce from any other document. That hash is published as a transaction on the Avalanche network, recorded across thousands of independent nodes worldwide. The result: no one — not even Validocus — can alter the signed version without the change being immediately detectable by any external verifier.
Why Avalanche?
The choice of blockchain network matters: each network has tradeoffs in speed, cost, decentralization, and energy use. After evaluating the leading options, Validocus chose Avalanche for three concrete reasons.
Finality speed
Avalanche confirms transactions in 1–2 seconds with absolute finality. Bitcoin takes 10–60 minutes; Ethereum mainnet 12 seconds but without immediate finality. For a user who just signed, seeing the blockchain confirmation in real time reinforces the experience.
Predictable costs
Avalanche fees are pennies, even under load. This allows us to register thousands of documents without passing the cost on to the customer. Ethereum can charge several dollars per transaction at peak times, which would be unworkable for our volume.
Energy efficiency
Avalanche uses proof-of-stake, not proof-of-work like Bitcoin. Energy consumption per transaction is orders of magnitude lower. For companies with ESG commitments, registering legal evidence without contradicting their environmental policy matters.
Immutability: why it matters legally
In evidence law, one of the oldest problems with digital documents is how easily they can be altered without a trace. A PDF can be edited with free software; a Word file is trivial to modify. Traditional schemes rely on trusted custodians (notaries, registries, certified platforms), but every custodian is a single point of failure: anyone who compromises the system or gains access to its internal database can rewrite the document without the victim knowing. Blockchain eliminates that single point: the hash is written across thousands of independent nodes worldwide. To alter the document and erase the trace, someone would need to control more than 50% of the Avalanche network simultaneously — economically unfeasible. This makes blockchain registration the strongest technical method available today to prove that a document existed on a specific date and was not modified afterward.
Use cases
Intellectual property and authorship
Manuscripts, designs, software, formulas. Registering the hash on blockchain proves the document's existence on a specific date without depending on notaries or national registries.
Contracts with international partners
When parties are in different countries and jurisdictions, neutral blockchain proof (independent of any country's public faith) makes the signature easier to recognize in any forum.
Internal audit and compliance
Companies with external audit obligations can show auditors that their signed documents are immutable from issuance, simplifying SOX, SARLAFT, and similar controls.
Sensitive documents in litigation
In cases with a high risk of alteration or later repudiation, blockchain registration freezes the signed version and removes any debate about integrity.
How does it work?
- 1
Open the public Validocus validator at validocus.com (the Validate document section).
- 2
Upload the signed PDF or paste the unique document code that appears on the certificate.
- 3
The validator locally computes the SHA-256 hash of the PDF — the file is not sent to Validocus, only the hash is.
- 4
It queries the Avalanche blockchain and returns the transaction where the hash was published, the block, the timestamp, and the signers.
- 5
If you want to validate manually, copy the transaction hash and paste it into a public explorer such as SnowTrace.io.
Frequently asked questions
What does it mean for a document to be registered on blockchain?
It means the SHA-256 hash of the signed document has been published on a public, immutable blockchain. That record is written permanently and is verifiable by anyone, independently of Validocus. It is a crypto-notarial seal: the document existed exactly as it is, on that exact date, and was not modified afterward.
Why does Validocus use Avalanche instead of Ethereum or Bitcoin?
Avalanche has confirmation times of 1–2 seconds versus 10+ minutes for Bitcoin or 12 seconds to several minutes for Ethereum mainnet. Fees are fractions of a cent, which lets us register thousands of documents without passing the cost on to the user. The network is proof-of-stake, which is far more energy-efficient. For document hash anchoring, Avalanche offers the best speed/cost/security tradeoff.
What happens if someone modifies the PDF after signing?
Any modification, no matter how small, changes the file's SHA-256 hash. Since the original hash was published on Avalanche with a timestamp, recomputing the hash of the modified file no longer matches the blockchain record. Validocus detects this automatically and flags the document as tampered with in the public validator. That property — cryptographic immutability — is what gives blockchain registration its evidentiary force.
How do I verify a document is really on the blockchain?
At validocus.com/en/#validator upload the PDF or paste the document code. The validator computes the hash locally, queries the Avalanche blockchain, and shows: the transaction that registered the hash, the block, the timestamp, and the address that published it. You can also verify manually on public explorers such as SnowTrace by pasting the transaction.
Do I need to know anything about crypto to use a blockchain signature?
No. The user never interacts with wallets, gas, private keys, or anything from the crypto world. Validocus handles the infrastructure under the hood: you sign a PDF as usual, and internally the platform computes the hash and publishes it on Avalanche automatically. The technical complexity stays hidden; the benefit (immutability and public verification) remains available.
Does the blockchain signature replace the traditional electronic signature?
It doesn't replace it — it reinforces it. You still have an electronic signature with Law 527 validity, a signer stroke, identity data, and optional video evidence. Blockchain adds another layer: the guarantee that the signed set has not been altered or backdated. It is the difference between a signature that is valid and a signature that is valid and impossible to tamper with undetected.
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