Glossary

Every term used on this site and in Entropa's product, explained in plain English. No background in AI, blockchains, or cryptography assumed — if a word here confuses you, that's a gap in this page, not in you.

AI agent

A piece of software that can make decisions on its own — reading information, deciding what to do, and taking an action — without a human clicking a button for every single step.

Sequencer

The single piece of software that receives submitted actions, puts them in order, and appends them to the log. Deliberately simple — one writer, one order, nothing to coordinate between independent parties.

Attestation (also: record)

One recorded, signed, priced fact — "this hash existed, at this time, and here's cryptographic proof of it." This is the actual product: $0.01 buys one attestation.

Receipt

The proof document you get back for a specific attestation — your record's content hash, its position in the chain (leaf index), and the block hash linking it to every record before it. You (or an auditor) can re-derive the hash chain independently to confirm nothing was altered.

Tamper-evident hash chain

An append-only structure where each record's block hash is computed from the record before it — the same core idea a blockchain uses, without the mining or consensus overhead. Every record is added to the end; changing anything already in the chain breaks every block hash that comes after it, which is what makes tampering detectable.

Record (also: leaf)

One entry in the log — the payload's content hash, its position (leaf index), the timestamp it was sequenced at, and the block hash linking it into the chain.

Block hash

A hash computed from the current record's content plus the previous record's block hash — this is what actually chains records together. Changing any past record changes every block hash after it, which is what makes tampering detectable without re-checking every record by hand.

Hash (also: fingerprint, digest)

A short string of letters and numbers computed from a piece of data, unique to that exact data. Change even one character of the original data, and the hash comes out completely different — so a matching hash proves nothing was altered.

202 Accepted

The HTTP response you get back the instant you submit — it means your submission has been queued, not that it's in the log yet. This is deliberate: your system is never left waiting on Entropa.

Tracking ID

A correlation handle returned with your 202 Accepted response, so you can find your submission again later. It is not itself proof of anything — the receipt you fetch afterward is.

Submission queue

Where an accepted submission waits, briefly, before it's actually appended to the log. This is what lets a burst of traffic get accepted immediately and sequenced moments later, instead of some of it being rejected outright.

Epoch

An isolated storage generation for the chain's history. Each epoch's data lives in its own permanently separate location, so one epoch's records can never be overwritten by another's — see the Durability section for why this matters.

API key

A private credential that identifies you as a specific customer when you submit an action to Entropa — like a password, but scoped specifically to this one purpose.

Scryon

Entropa's explorer — a website (scryon.entropa.space) demonstrating what your own private explorer looks like: browse and search records in a human-readable form, and generate a sample audit trail.

AML (anti-money laundering)

The set of laws, rules, and internal controls a bank or fintech must have to detect and report suspicious financial activity. An AI agent that screens transactions for AML purposes is exactly the kind of decision Entropa is built to make auditable.

KYC (know your customer)

The process of verifying who a customer actually is before doing business with them — identity documents, address, sometimes a liveness check. Often automated by an AI agent today, which is exactly what needs an independently verifiable record.

BSA (Bank Secrecy Act)

The main US federal law requiring financial institutions to keep records and file reports that help detect money laundering. Its recordkeeping rules are a primary reason a compliance program needs a tamper-evident audit trail, not just a database it controls itself.

FinCEN

The US Treasury bureau that writes and enforces the Bank Secrecy Act's rules, including what records a bank must keep to support its AML program's decisions.

Examiner

The regulator (or regulator's representative) who reviews a bank or fintech's compliance program, including asking it to justify specific automated decisions — sometimes years after the fact.

SR 11-7

Federal Reserve and OCC guidance on model risk management — it calls for documented, verifiable evidence of what a decisioning model actually did in production, not just how it was designed to behave.

HIPAA

A US law governing how healthcare information must be protected and handled.

HITRUST

A widely-recognized security certification, common in healthcare, that proves an organization meets a rigorous, independently-audited set of data-protection controls.

SOC 2

An independent audit report confirming a company has real, working controls around security, availability, and confidentiality of the systems it runs.

EU AI Act

European Union law regulating AI systems, with extra requirements for "high-risk" AI — including, under Article 12, automatic and tamper-resistant logging of what the AI system did.

NIST AI RMF

The US National Institute of Standards and Technology's voluntary framework for managing AI risk — it calls for documented, verifiable records of what an AI system actually did.