chore(utxo-core): added helper function to create attestation

TICKET: BTC-2047

Author: christopher-fong

modules/utxo-core/src/paygo/psbt/PayGoUtils.ts

@@ -11,6 +11,8 @@ import {
   ErrorPayGoAddressProofFailedVerification,
 } from './Errors';
 
+const NILLUUID = '00000000-0000-0000-0000-000000000000';
+
 /** This function adds the entropy and signature into the PSBT output unknown key vals.
  * We store the entropy so that we reconstruct the message <ENTROPY><ADDRESS><UUID>
  * to later verify.
@@ -45,7 +47,6 @@ export function addPayGoAddressProof(
 export function verifyPayGoAddressProof(
   psbt: utxolib.bitgo.UtxoPsbt,
   outputIndex: number,
-  uuid: string,
   verificationPubkey: Buffer
 ): void {
   const psbtOutputs = checkForOutput(psbt.data.outputs, outputIndex);
@@ -74,7 +75,7 @@ export function verifyPayGoAddressProof(
   const addressFromOutput = utxolib.address.fromOutputScript(output.script, psbt.network);
 
   // We construct our message <ENTROPY><ADDRESS><UUID>
-  const message = Buffer.concat([entropy, Buffer.from(addressFromOutput), Buffer.from(uuid)]);
+  const message = createPayGoAttestationBuffer(addressFromOutput, entropy);
 
   if (!verifyMessage(message.toString(), verificationPubkey, signature, utxolib.networks.bitcoin)) {
     throw new ErrorPayGoAddressProofFailedVerification();
@@ -108,3 +109,15 @@ export function getPayGoAddressProofOutputIndex(psbt: utxolib.bitgo.UtxoPsbt): n
 export function psbtOutputIncludesPaygoAddressProof(psbt: utxolib.bitgo.UtxoPsbt): boolean {
   return getPayGoAddressProofOutputIndex(psbt) !== undefined;
 }
+
+/** This function reconstructs the proof <ENTROPY><ADDRESS><UUID>
+ * given the address and entropy.
+ *
+ * @param address
+ * @param entropy
+ * @returns
+ */
+export function createPayGoAttestationBuffer(address: string, entropy: Buffer): Buffer {
+  const addressBuffer = Buffer.from(address);
+  return Buffer.concat([entropy, addressBuffer, Buffer.from(NILLUUID)]);
+}

modules/utxo-core/test/paygo/psbt/PayGoUtils.ts

@@ -8,6 +8,7 @@ import { checkForOutput } from 'bip174/src/lib/utils';
 
 import {
   addPayGoAddressProof,
+  createPayGoAttestationBuffer,
   getPayGoAddressProofOutputIndex,
   psbtOutputIncludesPaygoAddressProof,
   verifyPayGoAddressProof,
@@ -37,7 +38,7 @@ const attestationPubKey = dummyPub1.user.publicKey;
 const attestationPrvKey = dummyPub1.user.privateKey!;
 
 // UUID structure
-const nilUUID = '00000000-0000-0000-0000-000000000000';
+const nillUUID = '00000000-0000-0000-0000-000000000000';
 
 // our xpub converted to base58 address
 const addressToVerify = utxolib.address.toBase58Check(
@@ -47,7 +48,7 @@ const addressToVerify = utxolib.address.toBase58Check(
 );
 
 // this should be retuning a Buffer
-const addressProofBuffer = generatePayGoAttestationProof(nilUUID, Buffer.from(addressToVerify));
+const addressProofBuffer = generatePayGoAttestationProof(nillUUID, Buffer.from(addressToVerify));
 const addressProofMsgBuffer = parseVaspProof(addressProofBuffer);
 // We know that that the entropy is a set 64 bytes.
 const addressProofEntropy = addressProofMsgBuffer.subarray(0, 65);
@@ -73,25 +74,12 @@ describe('addPaygoAddressProof and verifyPaygoAddressProof', () => {
       });
   }
 
-  it('should fail a proof verification with wrong UUID', () => {
-    const outputIndex = 0;
-    const psbt = getTestPsbt();
-    addPayGoAddressProof(psbt, outputIndex, sig, addressProofEntropy);
-    const output = checkForOutput(psbt.data.outputs, outputIndex);
-    const proofInPsbt = getPaygoProprietaryKey(output.unknownKeyVals!);
-    assert(proofInPsbt.length === 1);
-    assert.throws(
-      () => verifyPayGoAddressProof(psbt, 0, '00000000-0000-0000-0000-000000000001', attestationPubKey),
-      (e: any) => e.message === 'Cannot verify the paygo address signature with the provided pubkey.'
-    );
-  });
-
   it('should add and verify a valid paygo address proof on the PSBT', () => {
     const psbt = getTestPsbt();
     psbt.addOutput({ script: utxolib.address.toOutputScript(addressToVerify, network), value: BigInt(10000) });
     const outputIndex = psbt.data.outputs.length - 1;
     addPayGoAddressProof(psbt, outputIndex, sig, addressProofEntropy);
-    verifyPayGoAddressProof(psbt, outputIndex, nilUUID, attestationPubKey);
+    verifyPayGoAddressProof(psbt, outputIndex, attestationPubKey);
   });
 
   it('should throw an error if there are multiple PayGo proprietary keys in the PSBT', () => {
@@ -104,7 +92,7 @@ describe('addPaygoAddressProof and verifyPaygoAddressProof', () => {
     assert(proofInPsbt.length !== 0);
     assert(proofInPsbt.length > 1);
     assert.throws(
-      () => verifyPayGoAddressProof(psbt, outputIndex, nilUUID, attestationPubKey),
+      () => verifyPayGoAddressProof(psbt, outputIndex, attestationPubKey),
       (e: any) => e.message === 'There are multiple paygo address proofs encoded in the PSBT. Something went wrong.'
     );
   });
@@ -114,7 +102,7 @@ describe('verifyPaygoAddressProof', () => {
   it('should throw an error if there is no PayGo address in PSBT', () => {
     const psbt = getTestPsbt();
     assert.throws(
-      () => verifyPayGoAddressProof(psbt, 0, nilUUID, attestationPubKey),
+      () => verifyPayGoAddressProof(psbt, 0, attestationPubKey),
       (e: any) => e.message === 'There is no paygo address proof encoded in the PSBT at output 0.'
     );
   });
@@ -146,3 +134,21 @@ describe('getPaygoAddressProofIndex', () => {
     );
   });
 });
+
+describe('createPayGoAttestationBuffer', () => {
+  it('should create a PayGo Attestation proof matching with original proof', () => {
+    const payGoAttestationProof = createPayGoAttestationBuffer(addressToVerify, addressProofEntropy);
+    assert.strictEqual(payGoAttestationProof.toString(), addressProofMsgBuffer.toString());
+    assert(Buffer.compare(payGoAttestationProof, addressProofMsgBuffer) === 0);
+  });
+
+  it('should create a PayGo Attestation proof that does not match with different uuid', () => {
+    const addressProofBufferDiffUuid = generatePayGoAttestationProof(
+      '00000000-0000-0000-0000-000000000001',
+      Buffer.from(addressToVerify)
+    );
+    const payGoAttestationProof = createPayGoAttestationBuffer(addressToVerify, addressProofEntropy);
+    assert.notStrictEqual(payGoAttestationProof.toString(), addressProofBufferDiffUuid.toString());
+    assert(Buffer.compare(payGoAttestationProof, addressProofBufferDiffUuid) !== 0);
+  });
+});