Merge pull request #2167 from antonilol/taproot-fee-tooltip

Add Taproot transaction feature tooltip with fee saving information

frontend/src/app/bitcoin.utils.ts

@@ -5,22 +5,27 @@ const P2SH_P2WSH_COST  = 35 * 4; // the WU cost for the non-witness part of P2SH
 
 export function calcSegwitFeeGains(tx: Transaction) {
   // calculated in weight units
-  let realizedGains = 0;
+  let realizedBech32Gains = 0;
   let potentialBech32Gains = 0;
   let potentialP2shGains = 0;
+  let potentialTaprootGains = 0;
+  let realizedTaprootGains = 0;
 
   for (const vin of tx.vin) {
     if (!vin.prevout) { continue; }
 
-    const isP2pkh = vin.prevout.scriptpubkey_type === 'p2pkh';
+    const isP2pk         = vin.prevout.scriptpubkey_type === 'p2pk';
-    const isP2sh  = vin.prevout.scriptpubkey_type === 'p2sh';
+    // const isBareMultisig = vin.prevout.scriptpubkey_type === 'multisig'; // type will be unknown, so use the multisig helper from the address labels
-    const isP2wsh = vin.prevout.scriptpubkey_type === 'v0_p2wsh';
+    const isBareMultisig = !!parseMultisigScript(vin.prevout.scriptpubkey_asm);
-    const isP2wpkh = vin.prevout.scriptpubkey_type === 'v0_p2wpkh';
+    const isP2pkh        = vin.prevout.scriptpubkey_type === 'p2pkh';
-    const isP2tr  = vin.prevout.scriptpubkey_type === 'v1_p2tr';
+    const isP2sh         = vin.prevout.scriptpubkey_type === 'p2sh';
+    const isP2wsh        = vin.prevout.scriptpubkey_type === 'v0_p2wsh';
+    const isP2wpkh       = vin.prevout.scriptpubkey_type === 'v0_p2wpkh';
+    const isP2tr         = vin.prevout.scriptpubkey_type === 'v1_p2tr';
 
     const op = vin.scriptsig ? vin.scriptsig_asm.split(' ')[0] : null;
     const isP2sh2Wpkh = isP2sh && !!vin.witness && op === 'OP_PUSHBYTES_22';
-    const isP2sh2Wsh = isP2sh && !!vin.witness && op === 'OP_PUSHBYTES_34';
+    const isP2sh2Wsh  = isP2sh && !!vin.witness && op === 'OP_PUSHBYTES_34';
 
     switch (true) {
       // Native Segwit - P2WPKH/P2WSH (Bech32)
@@ -28,41 +33,123 @@ export function calcSegwitFeeGains(tx: Transaction) {
       case isP2wsh:
       case isP2tr:
         // maximal gains: the scriptSig is moved entirely to the witness part
-        realizedGains += witnessSize(vin) * 3;
+        realizedBech32Gains += witnessSize(vin) * 3;
         // XXX P2WSH output creation is more expensive, should we take this into consideration?
         break;
 
       // Backward compatible Segwit - P2SH-P2WPKH
       case isP2sh2Wpkh:
         // the scriptSig is moved to the witness, but we have extra 21 extra non-witness bytes (48 WU)
-        realizedGains += witnessSize(vin) * 3 - P2SH_P2WPKH_COST;
+        realizedBech32Gains += witnessSize(vin) * 3 - P2SH_P2WPKH_COST;
         potentialBech32Gains += P2SH_P2WPKH_COST;
         break;
 
       // Backward compatible Segwit - P2SH-P2WSH
       case isP2sh2Wsh:
         // the scriptSig is moved to the witness, but we have extra 35 extra non-witness bytes
-        realizedGains += witnessSize(vin) * 3 - P2SH_P2WSH_COST;
+        realizedBech32Gains += witnessSize(vin) * 3 - P2SH_P2WSH_COST;
         potentialBech32Gains += P2SH_P2WSH_COST;
         break;
 
-      // Non-segwit P2PKH/P2SH
+      // Non-segwit P2PKH/P2SH/P2PK/bare multisig
       case isP2pkh:
       case isP2sh:
+      case isP2pk:
+      case isBareMultisig: {
         const fullGains = scriptSigSize(vin) * 3;
         potentialBech32Gains += fullGains;
         potentialP2shGains += fullGains - (isP2pkh ? P2SH_P2WPKH_COST : P2SH_P2WSH_COST);
         break;
+      }
+    }
 
-    // TODO: should we also consider P2PK and pay-to-bare-script (non-p2sh-wrapped) as upgradable to P2WPKH and P2WSH?
+    if (isP2tr) {
+      if (vin.witness.length === 1) {
+        // key path spend
+        // we don't know if this was a multisig or single sig (the goal of taproot :)),
+        // so calculate fee savings by comparing to the cheapest single sig input type: P2WPKH and say "saved at least ...%"
+        // the witness size of P2WPKH is 1 (stack size) + 1 (size) + 72 (low s signature) + 1 (size) + 33 (pubkey) = 108 WU
+        // the witness size of key path P2TR is 1 (stack size) + 1 (size) + 64 (signature) = 66 WU
+        realizedTaprootGains += 42;
+      } else {
+        // script path spend
+        // complex scripts with multiple spending paths can often be made around 2x to 3x smaller with the Taproot script tree
+        // because only the hash of the alternative spending path has the be in the witness data, not the entire script,
+        // but only assumptions can be made because the scripts themselves are unknown (again, the goal of taproot :))
+        // TODO maybe add some complex scripts that are specified somewhere, so that size is known, such as lightning scripts
+      }
+    } else {
+      const script = isP2sh2Wsh || isP2wsh ? vin.inner_witnessscript_asm : vin.inner_redeemscript_asm;
+      let replacementSize: number;
+      if (
+        // single sig
+        isP2pk || isP2pkh || isP2wpkh || isP2sh2Wpkh ||
+        // multisig
+        isBareMultisig || parseMultisigScript(script)
+      ) {
+        // the scriptSig and scriptWitness can all be replaced by a 66 witness WU with taproot
+        replacementSize = 66;
+      } else if (script) {
+        // not single sig, not multisig: the complex scripts
+        // rough calculations on spending paths
+        // every OP_IF and OP_NOTIF indicates an _extra_ spending path, so add 1
+        const spendingPaths = script.split(' ').filter(op => /^(OP_IF|OP_NOTIF)$/g.test(op)).length + 1;
+        // now assume the script could have been split in ${spendingPaths} equal tapleaves
+        replacementSize = script.length / 2 / spendingPaths +
+        // but account for the leaf and branch hashes and internal key in the control block
+          32 * Math.log2((spendingPaths - 1) || 1) + 33;
+      }
+      potentialTaprootGains += witnessSize(vin) + scriptSigSize(vin) * 4 - replacementSize;
     }
   }
 
   // returned as percentage of the total tx weight
-  return { realizedGains: realizedGains / (tx.weight + realizedGains) // percent of the pre-segwit tx size
+  return {
-         , potentialBech32Gains: potentialBech32Gains / tx.weight
+    realizedBech32Gains: realizedBech32Gains / (tx.weight + realizedBech32Gains), // percent of the pre-segwit tx size
-         , potentialP2shGains: potentialP2shGains / tx.weight
+    potentialBech32Gains: potentialBech32Gains / tx.weight,
-         };
+    potentialP2shGains: potentialP2shGains / tx.weight,
+    potentialTaprootGains: potentialTaprootGains / tx.weight,
+    realizedTaprootGains: realizedTaprootGains / tx.weight
+  };
+}
+
+/** extracts m and n from a multisig script (asm), returns nothing if it is not a multisig script */
+export function parseMultisigScript(script: string): void | { m: number, n: number } {
+  if (!script) {
+    return;
+  }
+  const ops = script.split(' ');
+  if (ops.length < 3 || ops.pop() !== 'OP_CHECKMULTISIG') {
+    return;
+  }
+  const opN = ops.pop();
+  if (!opN.startsWith('OP_PUSHNUM_')) {
+    return;
+  }
+  const n = parseInt(opN.match(/[0-9]+/)[0], 10);
+  if (ops.length < n * 2 + 1) {
+    return;
+  }
+  // pop n public keys
+  for (let i = 0; i < n; i++) {
+    if (!/^0((2|3)\w{64}|4\w{128})$/.test(ops.pop())) {
+      return;
+    }
+    if (!/^OP_PUSHBYTES_(33|65)$/.test(ops.pop())) {
+      return;
+    }
+  }
+  const opM = ops.pop();
+  if (!opM.startsWith('OP_PUSHNUM_')) {
+    return;
+  }
+  const m = parseInt(opM.match(/[0-9]+/)[0], 10);
+
+  if (ops.length) {
+    return;
+  }
+
+  return { m, n };
 }
 
 // https://github.com/shesek/move-decimal-point
@@ -128,7 +215,7 @@ export const formatNumber = (s, precision = null) => {
 };
 
 // Utilities for segwitFeeGains
-const witnessSize = (vin: Vin) => vin.witness.reduce((S, w) => S + (w.length / 2), 0);
+const witnessSize = (vin: Vin) => vin.witness ? vin.witness.reduce((S, w) => S + (w.length / 2), 0) : 0;
 const scriptSigSize = (vin: Vin) => vin.scriptsig ? vin.scriptsig.length / 2 : 0;
 
 // Power of ten wrapper
@@ -160,4 +247,4 @@ export function selectPowerOfTen(val: number) {
   }
 
   return selectedPowerOfTen;
-}
+}

frontend/src/app/components/address-labels/address-labels.component.ts

@@ -1,6 +1,7 @@
 import { Component, ChangeDetectionStrategy, Input, OnChanges } from '@angular/core';
 import { Vin, Vout } from '../../interfaces/electrs.interface';
 import { StateService } from 'src/app/services/state.service';
+import { parseMultisigScript } from 'src/app/bitcoin.utils';
 
 @Component({
   selector: 'app-address-labels',
@@ -98,41 +99,11 @@ export class AddressLabelsComponent implements OnChanges {
   }
 
   detectMultisig(script: string) {
-    if (!script) {
+    const ms = parseMultisigScript(script);
-      return;
-    }
-    const ops = script.split(' ');
-    if (ops.length < 3 || ops.pop() !== 'OP_CHECKMULTISIG') {
-      return;
-    }
-    const opN = ops.pop();
-    if (!opN.startsWith('OP_PUSHNUM_')) {
-      return;
-    }
-    const n = parseInt(opN.match(/[0-9]+/)[0], 10);
-    if (ops.length < n * 2 + 1) {
-      return;
-    }
-    // pop n public keys
-    for (let i = 0; i < n; i++) {
-      if (!/^0((2|3)\w{64}|4\w{128})$/.test(ops.pop())) {
-        return;
-      }
-      if (!/^OP_PUSHBYTES_(33|65)$/.test(ops.pop())) {
-        return;
-      }
-    }
-    const opM = ops.pop();
-    if (!opM.startsWith('OP_PUSHNUM_')) {
-      return;
-    }
-    const m = parseInt(opM.match(/[0-9]+/)[0], 10);
 
-    if (ops.length) {
+    if (ms) {
-      return;
+      this.label = $localize`:@@address-label.multisig:Multisig ${ms.m}:multisigM: of ${ms.n}:multisigN:`;
     }
-
-    this.label = $localize`:@@address-label.multisig:Multisig ${m}:multisigM: of ${n}:multisigN:`;
   }
 
   handleVout() {

frontend/src/app/components/tx-features/tx-features.component.html

@@ -1,13 +1,21 @@
-<span *ngIf="segwitGains.realizedGains && !segwitGains.potentialBech32Gains; else segwitTwo" class="badge badge-success mr-1" i18n-ngbTooltip="ngbTooltip about segwit gains" ngbTooltip="This transaction saved {{ segwitGains.realizedGains * 100 | number:  '1.0-0' }}% on fees by using native SegWit-Bech32" placement="bottom" i18n="tx-features.tag.segwit|SegWit">SegWit</span>
+<span *ngIf="segwitGains.realizedBech32Gains && !segwitGains.potentialBech32Gains; else segwitTwo" class="badge badge-success mr-1" i18n-ngbTooltip="ngbTooltip about segwit gains" ngbTooltip="This transaction saved {{ segwitGains.realizedBech32Gains * 100 | number:  '1.0-0' }}% on fees by using native SegWit-Bech32" placement="bottom" i18n="tx-features.tag.segwit|SegWit">SegWit</span>
 <ng-template #segwitTwo>
-  <span *ngIf="segwitGains.realizedGains && segwitGains.potentialBech32Gains else potentialP2shGains" class="badge badge-warning mr-1" i18n-ngbTooltip="ngbTooltip about double segwit gains" ngbTooltip="This transaction saved {{ segwitGains.realizedGains * 100 | number:  '1.0-0' }}% on fees by using SegWit and could save {{ segwitGains.potentialBech32Gains * 100 | number : '1.0-0' }}% more by fully upgrading to native SegWit-Bech32" placement="bottom" i18n="tx-features.tag.segwit|SegWit">SegWit</span>
+  <span *ngIf="segwitGains.realizedBech32Gains && segwitGains.potentialBech32Gains; else potentialP2shGains" class="badge badge-warning mr-1" i18n-ngbTooltip="ngbTooltip about double segwit gains" ngbTooltip="This transaction saved {{ segwitGains.realizedBech32Gains * 100 | number:  '1.0-0' }}% on fees by using SegWit and could save {{ segwitGains.potentialBech32Gains * 100 | number : '1.0-0' }}% more by fully upgrading to native SegWit-Bech32" placement="bottom" i18n="tx-features.tag.segwit|SegWit">SegWit</span>
   <ng-template #potentialP2shGains>
     <span *ngIf="segwitGains.potentialP2shGains" class="badge badge-danger mr-1" i18n-ngbTooltip="ngbTooltip about missed out gains" ngbTooltip="This transaction could save {{ segwitGains.potentialBech32Gains * 100 | number : '1.0-0' }}% on fees by upgrading to native SegWit-Bech32 or {{ segwitGains.potentialP2shGains * 100 | number:  '1.0-0' }}% by upgrading to SegWit-P2SH" placement="bottom"><del i18n="tx-features.tag.segwit|SegWit">SegWit</del></span>
   </ng-template>
 </ng-template>
-<span *ngIf="isTaproot; else noTaproot" class="badge badge-success mr-1" i18n-ngbTooltip="Taproot tooltip" ngbTooltip="This transaction uses Taproot" placement="bottom" i18n="tx-features.tag.taproot">Taproot</span>
+
-<ng-template #noTaproot>
+<span *ngIf="segwitGains.realizedTaprootGains && !segwitGains.potentialTaprootGains; else notFullyTaproot" class="badge badge-success mr-1" i18n-ngbTooltip="Tooltip about privacy and fees saved with taproot" ngbTooltip="This transaction uses Taproot and the user's thereby increased privacy and saved at least {{ segwitGains.realizedTaprootGains * 100 | number: '1.0-0' }}% on fees" placement="bottom" i18n="tx-features.tag.taproot|Taproot">Taproot</span>
-  <span class="badge badge-danger mr-1" i18n-ngbTooltip="No Taproot tooltip" ngbTooltip="This transaction could save on fees and improve privacy by using Taproot" placement="bottom"><del i18n="tx-features.tag.taproot">Taproot</del></span>
+<ng-template #notFullyTaproot>
+  <span *ngIf="segwitGains.realizedTaprootGains && segwitGains.potentialTaprootGains; else noTaproot" class="badge badge-warning mr-1" i18n-ngbTooltip="Tooltip about privacy and more fees that could be saved with more taproot" ngbTooltip="This transaction uses Taproot and thereby increased the user's privacy and already saved at least {{ segwitGains.realizedTaprootGains * 100 | number: '1.0-0' }}% on fees, but could save an additional {{ segwitGains.potentialTaprootGains * 100 | number: '1.0-0' }}% by fully using Taproot" placement="bottom" i18n="tx-features.tag.taproot|Taproot">Taproot</span>
+  <ng-template #noTaproot>
+    <span *ngIf="segwitGains.potentialTaprootGains; else taprootButNoGains" class="badge badge-danger mr-1" i18n-ngbTooltip="Tooltip about privacy and fees that could be saved with taproot" ngbTooltip="This transaction could increase the user's privacy and save {{ segwitGains.potentialTaprootGains * 100 | number: '1.0-0' }}% on fees by using Taproot" placement="bottom"><del i18n="tx-features.tag.taproot|Taproot">Taproot</del></span>
+    <ng-template #taprootButNoGains>
+      <span *ngIf="isTaproot" class="badge badge-success mr-1" i18n-ngbTooltip="Tooltip about privacy with taproot" ngbTooltip="This transaction uses Taproot and thereby increased the user's privacy" placement="bottom" i18n="tx-features.tag.taproot|Taproot">Taproot</span>
+    </ng-template>
+  </ng-template>
 </ng-template>
-<span *ngIf="isRbfTransaction; else rbfDisabled" class="badge badge-success" i18n-ngbTooltip="RBF tooltip" ngbTooltip="This transaction support Replace-By-Fee (RBF) allowing fee bumping" placement="bottom" i18n="tx-features.tag.rbf|RBF">RBF</span>
+
+<span *ngIf="isRbfTransaction; else rbfDisabled" class="badge badge-success" i18n-ngbTooltip="RBF tooltip" ngbTooltip="This transaction supports Replace-By-Fee (RBF) allowing fee bumping" placement="bottom" i18n="tx-features.tag.rbf|RBF">RBF</span>
 <ng-template #rbfDisabled><span class="badge badge-danger mr-1" i18n-ngbTooltip="RBF disabled tooltip" ngbTooltip="This transaction does NOT support Replace-By-Fee (RBF) and cannot be fee bumped using this method" placement="bottom"><del i18n="tx-features.tag.rbf|RBF">RBF</del></span></ng-template>

frontend/src/app/components/tx-features/tx-features.component.ts

@@ -12,9 +12,11 @@ export class TxFeaturesComponent implements OnChanges {
   @Input() tx: Transaction;
 
   segwitGains = {
-    realizedGains: 0,
+    realizedBech32Gains: 0,
     potentialBech32Gains: 0,
     potentialP2shGains: 0,
+    potentialTaprootGains: 0,
+    realizedTaprootGains: 0
   };
   isRbfTransaction: boolean;
   isTaproot: boolean;