How Beleg Works

Every entry you add gets a "hash" — a digital fingerprint created by running the entry's contents (title, body, date, timestamp) through a mathematical function called SHA-256. The same input always produces the same fingerprint. Even changing one character produces a completely different fingerprint.

Each entry's hash is computed from two things: the entry's own contents, and the previous entry's hash. This links them into a chain. The first entry links to a special "genesis" value (all zeros). Entry #2 links to entry #1. Entry #3 links to entry #2. And so on.

If anyone changed entry #1 after the fact, its hash would change. But entry #2's hash depends on entry #1's hash — so entry #2's hash would also change. And entry #3 depends on entry #2. The entire chain after the edit breaks. That's why it's called "append-only" — you can only add to the end, never change the past.

When you open a public proof page, the "Verify chain" button runs entirely in your browser. It downloads every entry's data, recomputes every hash from scratch using the same SHA-256 function, and checks that every link holds. If everything matches, you see a green banner. If anything was tampered with, you see red — and it tells you exactly which entry broke.

This is important: the verification does not trust Beleg's server. Your browser does the math independently. Even if Beleg's database were compromised, the verifier would catch it — because the attacker would need to recompute every hash in the chain to make a forgery pass, and the anchoring (below) makes even that impossible.

When a third party confirms an entry, their confirmation is itself added to the chain as a new sealed entry. It gets its own hash, linking to whatever came before it. So attestations carry the same tamper-evidence as everything else — they can't be edited, backdated, or removed after the fact.

Periodically, the latest hash in your chain is submitted to the Bitcoin blockchain via OpenTimestamps — a free, open protocol. Bitcoin's blockchain is a public ledger maintained by thousands of independent computers worldwide. Once your hash is recorded there, it is provably timestamped against infrastructure that nobody — not Beleg, not you, not anyone — controls or can rewrite.

This means: even if Beleg disappeared tomorrow, anyone with the .ots proof file could independently verify that your ledger existed at that date, using only open-source tools and the public Bitcoin blockchain. No trust in any company required.

Beleg proves integrity (nothing changed) and timing (when it was recorded). It does not prove truth (whether the claim is accurate). A sealed entry saying "shipped the prototype" proves you wrote those words on that date — proving the prototype actually shipped requires witnesses (attestations) and evidence (which future versions will support through verified email ingestion and payment connectors).

The SHA-256 hash function is a public standard — anyone can implement it. The chain structure is a standard Merkle-style linked list. OpenTimestamps is open source. Nothing about Beleg's verification requires proprietary software or trusting a third party. That's the point.