---
title: "Receipt chain: definition | KYA glossary"
url: https://knowyouragent.ch/en/knowledge/glossary/receipt-chain
lang: en
updated: 2026-10-12
license: © Innopulse Consulting GmbH
---

# Receipt chain

A receipt chain is a sequence of execution receipts in which every entry contains its predecessor's hash, so that any change or gap breaks the chain.

In the kya-chain/1 format every entry hash is the SHA-256 over the entry's canonical JSON. A chain alone proves its internal integrity, but not that it was not rebuilt entirely. Timestamps and signatures help against that.

## Example

An agent carries out five orders in one day; each creates a receipt containing the hash of the previous one. If someone later changes an amount in the third receipt, the hash values no longer match from that point on.

## How it differs

A database stores entries that can be changed; a receipt chain makes every change detectable. A blockchain spreads the chain across many participants; a receipt chain does not need that, as a [timestamp](https://knowyouragent.ch/en/knowledge/glossary/rfc-3161-timestamp) is enough as an independent anchor.

## In practice

- Store the chain so that entries can only be appended. A correction is a new entry, never a change to an existing one.
- Anchor the latest hash of the chain regularly with a timestamp from an independent authority; this also proves that the chain was not rebuilt afterwards.
- For audits or disputes, export the chain together with mandate and decision as an [evidence pack](https://knowyouragent.ch/en/knowledge/glossary/evidence-pack), so third parties can verify everything in one step.

## Role in KYA

KYA recomputes every hash in the chain and checks the chaining as well as the link to decision and mandate. The example “Tampered receipt chain” on the verification page shows how a later change is detected.

Related check: [Cryptographic integrity](https://knowyouragent.ch/en/method/checks) (`cryptographic_integrity`). Are signatures, disclosures, hash chains and manifest unchanged?

Receipt chains are kept, for example, by the reference implementation [Mandact](https://mandact.com/en/protocol?utm_source=knowyouragent.ch&utm_medium=referral&utm_campaign=glossar-beleg-kette) (from the operator of KYA); KYA recomputes every link.

[Verify now: open a matching example](https://knowyouragent.ch/en/verify?beispiel=manipuliert)

## Frequently asked questions

### What is a receipt chain?

A sequence of receipts in which every entry contains the hash of the previous one. This makes any later change detectable.

### Is a receipt chain a blockchain?

No. It uses the same chaining via hash values but needs no distributed network. A timestamp can anchor the time independently.

### How does KYA detect tampering?

KYA recomputes the hash values. If one differs, the chain is no longer intact from that point, and the verdict is “invalid”.

### How often should a receipt chain be timestamped?

That depends on the risk. For payments, a timestamp per transaction or per hour is common; the shorter the interval, the more precisely a point in time can be proven.

### Can a receipt chain be shortened?

Not unnoticed. Removing entries at the end changes the latest hash; if that hash was timestamped before, the shortening shows. That is why regular timestamps are worthwhile.

## Sources

- [KYA verification profile](https://knowyouragent.ch/en/standard/verification-profile)

## Related terms

- [Execution receipt](https://knowyouragent.ch/en/knowledge/glossary/execution-receipt)
- [Timestamp (RFC 3161)](https://knowyouragent.ch/en/knowledge/glossary/rfc-3161-timestamp)

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Quelle: https://knowyouragent.ch/en/knowledge/glossary/receipt-chain · KYA – Know Your Agent