feat: Liquid claim covenant

lib/liquid/TreeSort.ts

@@ -0,0 +1,64 @@
+import { Tapleaf } from '../consts/Types';
+import { LiquidSwapTree } from './consts/Types';
+
+type ProbabilityNode<T> = { probability: number; value: T };
+
+type TreeNode<T> = Tree<T> | T;
+type Tree<T> = [TreeNode<T>, TreeNode<T>];
+
+const subSortTree = <T>(nodes: ProbabilityNode<T>[]): TreeNode<T> => {
+  if (nodes.length === 1) {
+    return nodes[0].value;
+  } else if (nodes.length === 2) {
+    return [nodes[0].value, nodes[1].value];
+  }
+
+  const sum = nodes.reduce((sum, node) => sum + node.probability, 0);
+
+  let mid = 0;
+  let midSum = 0;
+
+  while (midSum < sum / 2) {
+    midSum += nodes[mid].probability;
+    mid++;
+  }
+
+  return [subSortTree(nodes.slice(0, mid)), subSortTree(nodes.slice(mid))];
+};
+
+export const sortTree = <T>(nodes: ProbabilityNode<T>[]): TreeNode<T> =>
+  subSortTree(nodes.sort((a, b) => b.probability - a.probability));
+
+export const assignTreeProbabilities = (
+  tree: Omit<LiquidSwapTree, 'tree'>,
+): ProbabilityNode<Tapleaf>[] => {
+  if (tree.covenantClaimLeaf) {
+    return [
+      {
+        probability: 51,
+        value: tree.covenantClaimLeaf,
+      },
+      {
+        probability: 25,
+        value: tree.claimLeaf,
+      },
+      {
+        probability: 24,
+        value: tree.refundLeaf,
+      },
+    ];
+  }
+
+  return [
+    {
+      probability: 51,
+      value: tree.claimLeaf,
+    },
+    {
+      probability: 49,
+      value: tree.refundLeaf,
+    },
+  ];
+};
+
+export { Tree, TreeNode, ProbabilityNode };

lib/liquid/Utils.ts

@@ -1,3 +1,5 @@
+import ops from '@boltz/bitcoin-ops';
+import { crypto, script } from 'bitcoinjs-lib';
 import { TxOutput, confidential } from 'liquidjs-lib';
 import { confidentialLiquid } from './init';
 
@@ -17,3 +19,32 @@ export const getOutputValue = (
       )
     : confidential.confidentialValueToSatoshi(output.value);
 };
+
+const getScriptIntrospectionWitnessScript = (outputScript: Buffer) =>
+  outputScript.subarray(2, 40);
+
+export const getScriptIntrospectionValues = (
+  outputScript: Buffer,
+): { version: number; script: Buffer } => {
+  const dec = script.decompile(outputScript)!;
+
+  switch (dec[0]) {
+    case ops.OP_1:
+      return {
+        version: 1,
+        script: getScriptIntrospectionWitnessScript(outputScript),
+      };
+
+    case ops.OP_0:
+      return {
+        version: 0,
+        script: getScriptIntrospectionWitnessScript(outputScript),
+      };
+
+    default:
+      return {
+        version: -1,
+        script: crypto.sha256(outputScript),
+      };
+  }
+};

lib/liquid/consts/Ops.ts

@@ -0,0 +1,6 @@
+// Reference: https://github.com/ElementsProject/elements/blob/master/doc/tapscript_opcodes.md#new-opcodes-for-additional-functionality
+export default {
+  OP_INSPECTOUTPUTSCRIPTPUBKEY: 0xd1,
+  OP_INSPECTOUTPUTASSET: 0xce,
+  OP_INSPECTOUTPUTVALUE: 0xcf,
+};

lib/liquid/consts/Types.ts

@@ -1,12 +1,18 @@
+import { BIP32Interface } from 'bip32';
+import { ECPairInterface } from 'ecpair';
 import { Transaction, TxOutput } from 'liquidjs-lib';
-import { RefundDetails } from '../../consts/Types';
+import { RefundDetails, SwapTree, Tapleaf } from '../../consts/Types';
 
-export type LiquidRefundDetails = Omit<RefundDetails, 'value'> &
+export type LiquidSwapTree = SwapTree & { covenantClaimLeaf?: Tapleaf };
+
+export type LiquidRefundDetails = Omit<RefundDetails, 'value' | 'swapTree'> &
   TxOutput & {
     legacyTx?: Transaction;
+    swapTree?: LiquidSwapTree;
     blindingPrivateKey?: Buffer;
   };
 
-export type LiquidClaimDetails = LiquidRefundDetails & {
+export type LiquidClaimDetails = Omit<LiquidRefundDetails, 'keys'> & {
   preimage: Buffer;
+  keys?: ECPairInterface | BIP32Interface;
 };

lib/liquid/index.ts

@@ -1,18 +1,29 @@
 import { getOutputValue } from './Utils';
+import * as Utils from './Utils';
 import Networks from './consts/Networks';
+import ops from './consts/Ops';
 import { LiquidClaimDetails, LiquidRefundDetails } from './consts/Types';
 import { init } from './init';
 import { constructClaimTransaction } from './swap/Claim';
 import { constructRefundTransaction } from './swap/Refund';
+import reverseSwapTree, {
+  Feature,
+  FeatureOption,
+} from './swap/ReverseSwapTree';
 import * as TaprootUtils from './swap/TaprootUtils';
 
 export {
+  ops,
+  Utils,
+  Feature,
   Networks,
   TaprootUtils,
+  FeatureOption,
   LiquidClaimDetails,
   LiquidRefundDetails,
   init,
   getOutputValue,
+  reverseSwapTree,
   constructClaimTransaction,
   constructRefundTransaction,
 };

lib/liquid/swap/Claim.ts

@@ -21,7 +21,7 @@ import { reverseBuffer, varuint } from 'liquidjs-lib/src/bufferutils';
 import { Network } from 'liquidjs-lib/src/networks';
 import { getHexString } from '../../Utils';
 import { OutputType } from '../../consts/Enums';
-import { validateInputs } from '../../swap/Claim';
+import { isRelevantTaprootOutput, validateInputs } from '../../swap/Claim';
 import { scriptBuffersToScript } from '../../swap/SwapUtils';
 import { getOutputValue } from '../Utils';
 import Networks from '../consts/Networks';
@@ -36,6 +36,29 @@ const getSighashType = (type: OutputType) =>
     ? Transaction.SIGHASH_DEFAULT
     : Transaction.SIGHASH_ALL;
 
+const validateLiquidInputs = (
+  utxos: LiquidClaimDetails[],
+  isRefund: boolean,
+) => {
+  validateInputs(utxos);
+
+  const taprootInputs = utxos.filter(isRelevantTaprootOutput);
+
+  if (isRefund && taprootInputs.some((utxo) => utxo.keys === undefined)) {
+    throw 'not all Taproot refund inputs have keys';
+  }
+
+  if (
+    taprootInputs.some(
+      (utxo) =>
+        utxo.keys === undefined &&
+        utxo.swapTree!.covenantClaimLeaf === undefined,
+    )
+  ) {
+    throw 'not all Taproot signature claims have keys';
+  }
+};
+
 /**
  * Claim swaps
  *
@@ -58,7 +81,7 @@ export const constructClaimTransaction = (
   timeoutBlockHeight?: number,
   isRefund = false,
 ): Transaction => {
-  validateInputs(utxos);
+  validateLiquidInputs(utxos, isRefund);
 
   if (
     utxos.some(
@@ -133,10 +156,10 @@ export const constructClaimTransaction = (
     },
   ]);
 
-  const addFeeOutput = () => {
+  const addFeeOutput = (isUnblinded = false) => {
     updater.addOutputs([
       {
-        amount: fee,
+        amount: isUnblinded ? fee - 1 : fee,
         asset: network.assetHash,
       },
     ]);
@@ -149,15 +172,16 @@ export const constructClaimTransaction = (
       pset.addOutput(
         new CreatorOutput(
           network.assetHash,
-          0,
+          // TODO: figure out flakiness with blinding 0 amount outputs
+          1,
           Buffer.of(ops.OP_RETURN),
           ecpair.makeRandom().publicKey,
           0,
         ).toPartialOutput(),
       );
     }
 
-    addFeeOutput();
+    addFeeOutput(blindingKey === undefined);
 
     blindPset(pset, utxos);
   } else {
@@ -170,15 +194,15 @@ export const constructClaimTransaction = (
 
   for (const [i, utxo] of utxos.entries()) {
     if (utxo.type === OutputType.Taproot) {
-      if (utxo.cooperative) {
+      if (utxo.cooperative || (!isRefund && utxo.keys === undefined)) {
         signatures.push(dummyTaprootSignature);
         continue;
       }
 
       const leafHash = tapLeafHash(
         isRefund ? utxo.swapTree!.refundLeaf : utxo.swapTree!.claimLeaf,
       );
-      const signature = utxo.keys.signSchnorr(
+      const signature = utxo.keys!.signSchnorr(
         pset.getInputPreimage(
           i,
           getSighashType(utxo.type),
@@ -194,7 +218,7 @@ export const constructClaimTransaction = (
           tapScriptSigs: [
             {
               signature: signature,
-              pubkey: toXOnly(utxo.keys.publicKey),
+              pubkey: toXOnly(utxo.keys!.publicKey),
               leafHash,
             },
           ],
@@ -203,7 +227,7 @@ export const constructClaimTransaction = (
       );
     } else {
       const signature = script.signature.encode(
-        utxo.keys.sign(pset.getInputPreimage(i, getSighashType(utxo.type))),
+        utxo.keys!.sign(pset.getInputPreimage(i, getSighashType(utxo.type))),
         getSighashType(utxo.type),
       );
       signatures.push(signature);
@@ -212,7 +236,7 @@ export const constructClaimTransaction = (
         i,
         {
           partialSig: {
-            pubkey: utxo.keys.publicKey,
+            pubkey: utxo.keys!.publicKey,
             signature,
           },
         },
@@ -253,13 +277,19 @@ export const constructClaimTransaction = (
             dummyTaprootSignature,
           ]);
         } else {
+          const isCovenantClaim = utxo.keys === undefined;
+
           const tapleaf = isRefund
             ? utxo.swapTree!.refundLeaf
-            : utxo.swapTree!.claimLeaf;
+            : isCovenantClaim
+              ? utxo.swapTree!.covenantClaimLeaf!
+              : utxo.swapTree!.claimLeaf;
 
           const witness = isRefund
             ? [signatures[i]]
-            : [signatures[i], utxo.preimage];
+            : isCovenantClaim
+              ? [utxo.preimage]
+              : [signatures[i], utxo.preimage];
 
           finals.finalScriptWitness = witnessStackToScriptWitness(
             witness.concat([