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Hashed Time-Locked Collateral Contract

BIP 197. Matthew Black.

BIP 197, Hashed Time-Locked Collateral Contract. A script for generalized debt agreement contract based on Hashed Time-Lock Contract (BIP 199) transactions according to the Atomic Loans specification (https://arxiv.org/pdf/1901.05117.pdf).

Status in the source: Draft. A reading of the public specification, not a copy of it and not a certification.

Hashed Time-Locked Collateral Contract is worth reading for the rule it actually adds: A script for generalized debt agreement contract based on Hashed Time-Lock Contract (BIP 199) transactions according to the Atomic Loans specification (https://arxiv.org/pdf/1901.05117.pdf).
Evidence
Primary paper
Re-measured
No
Assumptions
3
Records linked
8

Code

Source, repository, and what is actually hosted

  • BIP 197https://bips.dev/197
  • The source URL is not a GitHub repository. No code remote is invented.
  • Full text is not mirrored. Public availability is not a licence to copy the file onto this site.
  • Add to a reading list

01 Claim ledger

What the paper is allowed to say

Each row is a sentence already in the study. The status is the same on every row: a model claim, not a live measurement.

  1. Claim 01 · Paper model

    The rule

    A script for generalized debt agreement contract based on Hashed Time-Lock Contract (BIP 199) transactions according to the Atomic Loans specification (https://arxiv.org/pdf/1901.05117.pdf).

  2. Claim 02 · Paper model

    What was already failing

    A payment or a bridge that cannot name the dispute path is a custodial promise with extra steps.

  3. Claim 03 · Paper model

    What the number does not mean

    The source marks this draft. It is not a live consensus rule just because it has a number.

  4. Claim 04 · Paper model

    What a builder should be able to point at

    An implementation either constrains HTLCC, P2SH or it is a different design.

02 Three cuts

Observation, model, falsifier

A desk does not stop at the summary. Each claim is cut three ways, using only this study's own assumptions and checks. Nothing here is a new figure.

  1. 01 The rule

    Observation

    What the study says

    A script for generalized debt agreement contract based on Hashed Time-Lock Contract (BIP 199) transactions according to the Atomic Loans specification (https://arxiv.org/pdf/1901.05117.pdf).

    Model

    What has to hold

    You are implementing BIP 197 at the status the text itself states: Draft.

    Falsifier

    What would retire it

    What is the timeout in Hashed Time-Locked Collateral Contract, and who can take the coins when it expires?

  2. 02 What was already failing

    Observation

    What the study says

    A payment or a bridge that cannot name the dispute path is a custodial promise with extra steps.

    Model

    What has to hold

    The object that has to change is HTLCC, P2SH. A neighbouring document with a similar name is not this one.

    Falsifier

    What would retire it

    Which chain, if any, adjudicates the dispute?

  3. 03 What the number does not mean

    Observation

    What the study says

    The source marks this draft. It is not a live consensus rule just because it has a number.

    Model

    What has to hold

    You are implementing BIP 197 at the status the text itself states: Draft.

    Falsifier

    What would retire it

    Which fields are committed: HTLCC, P2SH?

  4. 04 What a builder should be able to point at

    Observation

    What the study says

    An implementation either constrains HTLCC, P2SH or it is a different design.

    Model

    What has to hold

    The object that has to change is HTLCC, P2SH. A neighbouring document with a similar name is not this one.

    Falsifier

    What would retire it

    Which fields are committed: HTLCC, P2SH?

03 Sequence

One action, as an operating tape

  1. 01Open BIP 197 and read the status line before the examples.
  2. 02Write down the rule in one sentence. A fair version of that sentence is: A script for generalized debt agreement contract based on Hashed Time-Lock Contract (BIP 199) transactions according to the Atomic Loans specification (https://arxiv.org/pdf/1901.05117.pdf).
  3. 03Name the object that changes: HTLCC, P2SH.
  4. 04Ask what an old client, an old contract, or an offline counterparty does. If the document is silent, the silence is part of the design.

04 Load-bearing

The argument, and where a pitch drops it

  1. What the text is allowed to settle

    The cut

    Bitcoin Improvement Proposal 197 can settle the shape of Hashed Time-Locked Collateral Contract. It cannot settle whether a later client, a later fork, or a later wallet still does this.

    Why it carries weight

    If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.

    Where it is dropped

    A later client, parameter or reward formula is a different object from this paragraph.

  2. What this page will not pretend

    The cut

    There is no benchmark, no adoption number, and no claim that the mechanism is safe outside the assumptions written in the source.

    Why it carries weight

    If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.

    Where it is dropped

    The source marks this draft. It is not a live consensus rule just because it has a number.

05 Register

What has to be true

  • Model · Not re-measured

    You are implementing BIP 197 at the status the text itself states: Draft.

  • Model · Not re-measured

    The object that has to change is HTLCC, P2SH. A neighbouring document with a similar name is not this one.

  • Model · Not re-measured

    This page is not a guide to moving funds.

06 Divergence

What happened after the paper

The source marks this draft. It is not a live consensus rule just because it has a number. Later documents can narrow, replace, or ignore this one. Cite the number you mean.

A later client, parameter set, or reward formula is a different object. Cite this paper for the mechanism. Cite a primary release for the network. This desk has not re-run the proof.

07 Pre-mortem

What to check before you use the idea

  4. 0 of 3 marked on this browser. A mark is a reading note, not a pass, a rating, or a recommendation.

08 Anatomy

The paper, in the order a builder needs

The problem it names

A payment or a bridge that cannot name the dispute path is a custodial promise with extra steps.

What the design proposes

  • A script for generalized debt agreement contract based on Hashed Time-Lock Contract (BIP 199) transactions according to the Atomic Loans specification (https://arxiv.org/pdf/1901.05117.pdf).
  • A Hashed Time-Locked Collateral Contract (HTLCC) consists of two scripts that permit a designated party (the "borrower") to lock funds on the Bitcoin chain for a specified amount of time as collateral in a debt agreement where the loan principal is denominated in a currency on another blockchain.
  • We denote the blockchain on which the loan principal is issued the principal blockchain.

How the mechanism is specified

  • Taken from the specification, the next constraint is: A Hashed Time-Locked Collateral Contract (HTLCC) consists of two scripts that permit a designated party (the "borrower") to lock funds on the Bitcoin chain for a specified amount of time as collateral in a debt agreement where the loan principal is denominated in a currency on another blockchain.
  • Locate HTLCC, P2SH in BIP 197 and apply it to one transaction or call.
  • Then check the failure the class of rule always has: a node that did not upgrade, a reverted call, a replayed signature, or a peer that does not speak the message.

What this page does not treat as proven

  • A specification of a hash lock is not a working route, and not a guarantee the counterparty is online.
  • This page is not a guide to moving funds.
  • The source marks this draft. It is not a live consensus rule just because it has a number.

Why the desk still reads it

Use BIP 197 when a pitch says 'Hashed Time-Locked Collateral Contract' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.

09 Lexicon

Terms, opened into the record

BIP 197
The public text titled Hashed Time-Locked Collateral Contract.
Draft
The document's own label for how finished the text is. It is not a market fact.

10 Repository

Every linked record on this page

Underlined words open a page that already exists: a concept, a protocol profile, a failure record, or another paper. If a word is not underlined, this desk does not have a record for it.

Protocols

This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.

Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.