BIP 197: Hashed Time-Locked Collateral Contract

matthewjablack commented at 2:30 pm on March 27, 2019: contributor

Hello all,

This proposal went through the mailing list: https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2019-March/016805.html without any further discussion. Currently this proposal has been implemented by in the ChainAbstractionLayer (https://github.com/liquality/chainabstractionlayer/tree/dev). I would like to kindly ask for BIP # assignment and have this merged into upstream bips.

Cheers,

Matthew Black

matthewjablack renamed this:
~~BIP 200: Hashed Time-Locked Collateral Contract transactions~~
BIP 200: Hashed Time-Locked Collateral Contract
on Mar 27, 2019

matthewjablack renamed this:
~~BIP 200: Hashed Time-Locked Collateral Contract~~
BIP ???: Hashed Time-Locked Collateral Contract
on Mar 27, 2019

matthewjablack renamed this:
~~BIP ???: Hashed Time-Locked Collateral Contract~~
BIP 200: Hashed Time-Locked Collateral Contract
on Mar 27, 2019

luke-jr renamed this:
~~BIP 200: Hashed Time-Locked Collateral Contract~~
New BIP: Hashed Time-Locked Collateral Contract
on Mar 28, 2019

luke-jr added the label New BIP on Mar 28, 2019

luke-jr commented at 0:24 am on March 28, 2019: member

Never self-assign BIP numbers.

luke-jr commented at 0:24 am on March 28, 2019: member

(BIP 200 is already reserved for something else)

in bip-0200.mediawiki:32 in ef79fffc50 outdated

27+These funds are locked into two scripts. Refundable Collateral and Seizable Collateral scripts. The funds sent to these scripts represent the percentage of collateral that each party is entitled to in the case that repayment fails, and the parties don't opt for liquidation.
28+
29+The Refundable Collateral script takes the following form:
30+
31+    OP_IF
32+        OP_SIZE OP_PUSHDATA(1) <secret b2 length> OP_EQUALVERIFY [HASHOP] <secret b2> OP_EQUALVERIFY OP_DUP OP_HASH160 <borrower pubkey hash> OP_EQUALVERIFY OP_CHECKSIG

luke-jr commented at 0:28 am on March 28, 2019:

This doesn’t make sense to me. Secret b2 length must always be 1 for EQUALVERIFY to pass… And then you’re hashing the size of the 2nd stack item and comparing it to secret b2???

matthewjablack commented at 6:56 am on March 28, 2019:

So the purpose of this script is not to ensure that secret b2 length must always be 1, it is actually using the OP_SIZE opcode to check the length of the secret. That pops the length of the secret to the stack, and then pushes secret b2 length to the stack, which is compared with OP_EQUALVERIFY.

Example: The next item on the stack is a secret of length 32 bytes. OP_SIZE is called, which pushes 20 to the stack. <secret b2 length> is 20, which pushes 20 to the stack. OP_EQUALVERIFY succeeds.

So an example of items pushed to the stack would be

01. 01
12. 6443b923b04a21839c44c8f5e54c360af7b5a4541f11511584b6e413a358aa80
23. 02dbf5bf2e114c5e778c904cf8569c77cc18bb32df27bd3d3c539d898ea7150f15
34. 3045022100b302c7fb9cab9978df85ab25be7f8705367e8168c3a6c5c40014acca150c1f6d0220776a0a595b3cec56fe5452a272729cc1215b029c61a2f49a8dffc6ddb96a90a6

Where

is OPCODE 51
is the secret
is the pubkey
is the signature

within btcdeb this would look like this

0btcdeb --txin=0100000001899afa569a843d13bb5b1002f1ba1e9122db5ae7a6a8d913d6cb32cad698e85b010000006b483045022100e408b398b2850c8c8130964fbd4c596aa450ecb5e4c063893b1db49847ac9fea02204d35647416be8a9d2a25484361c5d190afdcab3d79673eade297d207a274427b012102068b045421cc93a1100fa8bfbd81d5edb82c70b44f92666742e4edd46af847bbffffffff02a08601000000000017a914536f6b5a66eb7db8d729c30954da27a1ba748f3187a23fd211000000001976a9140bb2fc4ea28987e8138420c07c95c40b3433e48f88ac00000000 --tx=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

Let me know if that makes sense @luke-jr and if this requires more documentation for the BIP

luke-jr commented at 7:16 am on March 28, 2019:

But you have an OP_PUSHDATA(1) after OP_SIZE

matthewjablack commented at 7:29 am on March 28, 2019:

Ah! yes my bad. Thanks for catching that. That should be simply 01

matthewjablack commented at 7:37 am on March 28, 2019:

Updated

in bip-0200.mediawiki:11 in ef79fffc50 outdated

 6+          Tony Cai <tony@atomicloans.io>
 7+          Atomic Loans team <info@atomicloans.io>
 8+  Comments-Summary: No comments yet.
 9+  Comments-URI: TBD
10+  Status: Proposal
11+  Type: Informational

luke-jr commented at 0:31 am on March 28, 2019:

This should be Standards Track

in bip-0200.mediawiki:10 in ef79fffc50 outdated

 5+  Author: Matthew Black <matthew@atomicloans.io>
 6+          Tony Cai <tony@atomicloans.io>
 7+          Atomic Loans team <info@atomicloans.io>
 8+  Comments-Summary: No comments yet.
 9+  Comments-URI: TBD
10+  Status: Proposal

luke-jr commented at 0:31 am on March 28, 2019:

This should be Draft

luke-jr commented at 0:31 am on March 28, 2019: member

For a BIP number to be assigned, you must add a Backwards compatibility section.

in bip-0200.mediawiki:32 in 6d88fae317 outdated

27+These funds are locked into two scripts. Refundable Collateral and Seizable Collateral scripts. The funds sent to these scripts represent the percentage of collateral that each party is entitled to in the case that repayment fails, and the parties don't opt for liquidation.
28+
29+The Refundable Collateral script takes the following form:
30+
31+    OP_IF
32+        OP_SIZE <secret b2 length> OP_EQUALVERIFY [HASHOP] <secret hash b2> OP_EQUALVERIFY OP_DUP OP_HASH160 <borrower pubkey hash> OP_EQUALVERIFY OP_CHECKSIG

luke-jr commented at 7:46 am on March 28, 2019:

Why are you checking the length and the hash separately? If the hash is secure, only two identical items of the same length will match. Additionally, SHA2 hashes explicitly commit to the length.

matthewjablack commented at 7:51 am on March 28, 2019:

This script checks the length because it’s being used alongside the HTLPC (initially Ethereum with ERC 1850 https://github.com/ethereum/EIPs/pull/1850). The SHA256 function in Ethereum takes up to 32 bytes, no more. Therefore, it is necessary to ensure that the secret b2 cannot be more than 32 bytes. Otherwise, you could end up with a situation where the secret corresponds to the correct secrethash on Bitcoin, but not Ethereum.

matthewjablack commented at 7:56 am on March 28, 2019:

Ex. btcdeb 216443b923b04a21839c44c8f5e54c360af7b5a4541f11511584b6e413a358aa8080a8 will be a different result than btcdeb 206443b923b04a21839c44c8f5e54c360af7b5a4541f11511584b6e413a358aa80a8 which is problematic for Ethereum

luke-jr commented at 8:43 am on March 28, 2019:

You should write this up in the (currently non-existent) Rationale section. ;)

(There’s also too many Ethereum references elsewhere - remember BIPs are about Bitcoin, so probably it only makes sense to reference Ethereum-side stuff in Rationale)

matthewjablack commented at 11:29 pm on March 28, 2019:

Great idea! Reduced talk of Ethereum and added Rationale section.

matthewjablack cross-referenced this on Mar 28, 2019 from issue ERC 1850 - Hashed Time-Locked Principal Contract Standard by matthewjablack

matthewjablack cross-referenced this on Mar 28, 2019 from issue ERC 1850 Discussion by matthewjablack

luke-jr renamed this:
~~New BIP: Hashed Time-Locked Collateral Contract~~
BIP 197: Hashed Time-Locked Collateral Contract
on Mar 29, 2019

luke-jr commented at 5:46 am on March 29, 2019: member

Please use BIP number 197 (and purge the incorrect number from the git branch history)

matthewjablack force-pushed on Mar 29, 2019

New BIP (0197) - HLTCC transactions 823f6ac0db

matthewjablack force-pushed on Mar 29, 2019

in bip-0197.mediawiki:7 in 823f6ac0db outdated

0@@ -0,0 +1,156 @@
1+<pre>
2+  BIP: 197
3+  Layer: Applications
4+  Title: Hashed Time-Locked Collateral Contract
5+  Author: Matthew Black <matthew@atomicloans.io>
6+          Tony Cai <tony@atomicloans.io>
7+          Atomic Loans team <info@atomicloans.io>

luke-jr commented at 9:39 pm on March 29, 2019:

Not sure teams can be authors; either way, this needs to match what’s in README

matthewjablack commented at 9:54 pm on March 29, 2019:

Removed Atomic Loans team <info@atomicloans.io> from Author list

Remove team email from Author list c260fcb69a

Fix readme for BIP-197 to match title 26cff22dbb

in bip-0197.mediawiki:4 in 823f6ac0db outdated

0@@ -0,0 +1,156 @@
1+<pre>
2+  BIP: 197
3+  Layer: Applications
4+  Title: Hashed Time-Locked Collateral Contract

luke-jr commented at 9:39 pm on March 29, 2019:

Needs to match README

matthewjablack commented at 9:55 pm on March 29, 2019:

Changed title in README for BIP 197 to Hashed Time-Locked Collateral Contract

luke-jr merged this on Mar 29, 2019

luke-jr closed this on Mar 29, 2019

BIP 197: Hashed Time-Locked Collateral Contract #773