bitcoin manual withdraw when exchange has btc currency

packages/taler-util/package.json

@@ -40,6 +40,7 @@
     "typescript": "^4.5.5"
   },
   "dependencies": {
+    "bech32-buffer": "^0.2.0",
     "big-integer": "^1.6.51",
     "jed": "^1.1.1",
     "tslib": "^2.3.1"

packages/taler-util/src/bitcoin.ts

@@ -0,0 +1,63 @@
+/*
+ This file is part of GNU Taler
+ (C) 2019 Taler Systems S.A.
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+import { AmountJson } from "."
+import { Amounts, } from "./amounts"
+import { getRandomBytes, decodeCrock, encodeCrock } from "./talerCrypto"
+import { encode as segwitEncode } from "bech32-buffer"
+/**
+ *
+ * @author sebasjm
+ */
+
+export interface SegwitAddrs {
+  segwitAddr1: string,
+  segwitAddr2: string,
+}
+
+function buf2hex(buffer: Uint8Array) { // buffer is an ArrayBuffer
+  return [...new Uint8Array(buffer)]
+    .map(x => x.toString(16).padStart(2, '0'))
+    .join('');
+}
+
+export function generateSegwitAddress(reservePub: string): SegwitAddrs {
+  const pub = decodeCrock(reservePub)
+
+  const first_rnd = getRandomBytes(4)
+  const second_rnd = new Uint8Array(first_rnd.length)
+  second_rnd.set(first_rnd)
+
+  first_rnd[0] = first_rnd[0] & 0b0111_1111
+  second_rnd[0] = second_rnd[0] | 0b1000_0000
+
+  const first_part = new Uint8Array(first_rnd.length + pub.length / 2)
+  first_part.set(first_rnd, 0)
+  first_part.set(pub.subarray(0, 16), 4)
+  const second_part = new Uint8Array(first_rnd.length + pub.length / 2)
+  second_part.set(first_rnd, 0)
+  second_part.set(pub.subarray(16, 32), 4)
+
+  return {
+    segwitAddr1: segwitEncode("bc", first_part),
+    segwitAddr2: segwitEncode("bc", second_part),
+  }
+}
+
+// https://github.com/bitcoin/bitcoin/blob/master/src/policy/policy.cpp
+export function segwitMinAmount(): AmountJson {
+  return Amounts.parseOrThrow("BTC:0.00000294")
+}

packages/taler-util/src/index.ts

@@ -23,6 +23,7 @@ export { fnutil } from "./fnutils.js";
 export * from "./kdf.js";
 export * from "./talerCrypto.js";
 export * from "./http-status-codes.js";
+export * from "./bitcoin.js";
 export {
   randomBytes,
   secretbox,

packages/taler-wallet-webextension/src/wallet/ReserveCreated.stories.tsx

@@ -51,3 +51,15 @@ export const IBAN = createExample(TestedComponent, {
   },
   exchangeBaseUrl: "https://exchange.demo.taler.net",
 });
+
+export const Bitcoin = createExample(TestedComponent, {
+  reservePub: "0ZSX8SH0M30KHX8K3Y1DAMVGDQV82XEF9DG1HC4QMQ3QWYT4AF00",
+  payto:
+    "payto://bitcoin/bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4?amount=BTC:0.1&subject=0ZSX8SH0M30KHX8K3Y1DAMVGDQV82XEF9DG1HC4QMQ3QWYT4AF00",
+  amount: {
+    currency: "BTC",
+    value: 0,
+    fraction: 14000000,
+  },
+  exchangeBaseUrl: "https://exchange.demo.taler.net",
+});

packages/taler-wallet-webextension/src/wallet/ReserveCreated.tsx

@@ -1,4 +1,11 @@
-import { AmountJson, parsePaytoUri, i18n } from "@gnu-taler/taler-util";
+import {
+  AmountJson,
+  parsePaytoUri,
+  i18n,
+  generateSegwitAddress,
+  Amounts,
+  segwitMinAmount,
+} from "@gnu-taler/taler-util";
 import { Fragment, h, VNode } from "preact";
 import { BankDetailsByPaytoType } from "../components/BankDetailsByPaytoType";
 import { QR } from "../components/QR";
@@ -30,18 +37,62 @@ export function ReserveCreated({
       </div>
     );
   }
+  function TransferDetails(): VNode {
+    if (!paytoURI) return <Fragment />;
+    if (paytoURI.targetType === "bitcoin") {
+      const { segwitAddr1, segwitAddr2 } = generateSegwitAddress(reservePub);
+      const min = segwitMinAmount();
       return (
-    <Fragment>
         <section>
-        <h1>
-          <i18n.Translate>Exchange is ready for withdrawal</i18n.Translate>
-        </h1>
           <p>
             <i18n.Translate>
-            To complete the process you need to wire
+              Bitcoin exchange need a transaction with 3 output, one output is
-            <b>{amountToString(amount)}</b> to the exchange bank account
+              the exchange account and the other two are segwit fake address for
+              metadata with an minimum amount. Reserve pub : {reservePub}
             </i18n.Translate>
           </p>
+          <p>
+            <i18n.Translate>
+              In bitcoincore wallet use 'Add Recipient' button to add two
+              additional recipient and copy adresses and amounts
+            </i18n.Translate>
+            <ul>
+              <li>
+                {paytoURI.targetPath} {Amounts.stringifyValue(amount)} BTC
+              </li>
+              <li>
+                {segwitAddr1} {Amounts.stringifyValue(min)} BTC
+              </li>
+              <li>
+                {segwitAddr2} {Amounts.stringifyValue(min)} BTC
+              </li>
+            </ul>
+            <i18n.Translate>
+              In Electrum wallet paste the following three lines in 'Pay to'
+              field :
+            </i18n.Translate>
+            <ul>
+              <li>
+                {paytoURI.targetPath},{Amounts.stringifyValue(amount)}
+              </li>
+              <li>
+                {segwitAddr1},{Amounts.stringifyValue(min)}
+              </li>
+              <li>
+                {segwitAddr2},{Amounts.stringifyValue(min)}
+              </li>
+            </ul>
+            <i18n.Translate>
+              Make sure the amount show{" "}
+              {Amounts.stringifyValue(Amounts.sum([amount, min, min]).amount)}{" "}
+              BTC, else you have to change the base unit to BTC
+            </i18n.Translate>
+          </p>
+        </section>
+      );
+    }
+    return (
+      <section>
         <BankDetailsByPaytoType
           amount={amountToString(amount)}
           exchangeBaseUrl={exchangeBaseUrl}
@@ -57,10 +108,27 @@ export function ReserveCreated({
           </WarningBox>
         </p>
       </section>
+    );
+  }
+
+  return (
+    <Fragment>
+      <section>
+        <h1>
+          <i18n.Translate>Exchange is ready for withdrawal</i18n.Translate>
+        </h1>
+        <p>
+          <i18n.Translate>
+            To complete the process you need to wire{` `}
+            <b>{amountToString(amount)}</b> to the exchange bank account
+          </i18n.Translate>
+        </p>
+      </section>
+      <TransferDetails />
       <section>
         <p>
           <i18n.Translate>
-            Alternative, you can also scan this QR code or open
+            Alternative, you can also scan this QR code or open{" "}
             <a href={payto}>this link</a> if you have a banking app installed
             that supports RFC 8905
           </i18n.Translate>

pnpm-lock.yaml

@@ -164,6 +164,7 @@ importers:
     specifiers:
       '@types/node': ^17.0.17
       ava: ^4.0.1
+      bech32-buffer: ^0.2.0
       big-integer: ^1.6.51
       esbuild: ^0.14.21
       jed: ^1.1.1
@@ -172,6 +173,7 @@ importers:
       tslib: ^2.3.1
       typescript: ^4.5.5
     dependencies:
+      bech32-buffer: 0.2.0
       big-integer: 1.6.51
       jed: 1.1.1
       tslib: 2.3.1
@@ -8248,6 +8250,11 @@ packages:
       tweetnacl: 0.14.5
     dev: true
 
+  /bech32-buffer/0.2.0:
+    resolution: {integrity: sha512-Ez8s82a+Xnn/m3/ftGaQJUSFG4EwNIj9adIJBw8OrHASQsXgvwLSducbcJ9El0rsrwJYJ71yBhC/hZzz3FPSCQ==}
+    engines: {node: '>=8'}
+    dev: false
+
   /better-opn/2.1.1:
     resolution: {integrity: sha512-kIPXZS5qwyKiX/HcRvDYfmBQUa8XP17I0mYZZ0y4UhpYOSvtsLHDYqmomS+Mj20aDvD3knEiQ0ecQy2nhio3yA==}
     engines: {node: '>8.0.0'}