fix: wipe the exported private key from the DOM on any view leave (closes #221)

src/popup/views/addWallet.js

@@ -1,4 +1,11 @@
-const { $, showView, showFlash, goBack, clearViewStack } = require("./helpers");
+const {
+    $,
+    showView,
+    showFlash,
+    goBack,
+    clearViewStack,
+    onViewLeave,
+} = require("./helpers");
 const {
     generateMnemonic,
     hdWalletFromMnemonic,
@@ -66,13 +73,23 @@ function switchMode(mode) {
     $("add-wallet-password-hint").textContent = PASSWORD_HINTS[mode];
 }
 
-function show() {
+// Wipe the secret material this screen holds in the DOM: a generated or
+// pasted recovery phrase, an imported private key or extended private key,
+// and the password that would encrypt them. Registered as the view-leave
+// handler as well as run on entry, so none of it survives in the hidden
+// view after the user navigates away by any route, including the Settings
+// gear and the import itself.
+function clear() {
     $("wallet-mnemonic").value = "";
     $("import-private-key").value = "";
     $("import-xprv-key").value = "";
     $("add-wallet-password").value = "";
     $("add-wallet-password-confirm").value = "";
     $("add-wallet-phrase-warning").style.visibility = "hidden";
+}
+
+function show() {
+    clear();
     switchMode("mnemonic");
     showView("add-wallet");
 }
@@ -288,6 +305,8 @@ async function importXprvKey(ctx) {
 }
 
 function init(ctx) {
+    onViewLeave("add-wallet", clear);
+
     // Tab click handlers
     $("tab-mnemonic").addEventListener("click", () => switchMode("mnemonic"));
     $("tab-privkey").addEventListener("click", () => switchMode("privkey"));

src/popup/views/addressDetail.js

@@ -2,7 +2,6 @@ const {
     $,
     showView,
     showFlash,
-    flashCopyFeedback,
     balanceLinesForAddress,
     addressDotHtml,
     addressTitle,
@@ -27,8 +26,7 @@ const {
 } = require("./send");
 const { log } = require("../../shared/log");
 const makeBlockie = require("ethereum-blockies-base64");
-const { decryptWithPassword } = require("../../shared/vault");
-const { getSignerForAddress } = require("../../shared/wallet");
+const exportPrivkey = require("./exportPrivkey");
 const { walletDefect } = require("../../shared/walletDefects");
 
 // The defect of the wallet the selected address belongs to, or null. Both the
@@ -321,81 +319,12 @@ function init(_ctx) {
             showFlash(defect.shortMessage);
             return;
         }
-        pushCurrentView();
-        const wallet = state.wallets[state.selectedWallet];
-        const addr = wallet.addresses[state.selectedAddress];
-        const blockieEl = $("export-privkey-jazzicon");
-        blockieEl.innerHTML = "";
-        const bImg = document.createElement("img");
-        bImg.src = makeBlockie(addr.address);
-        bImg.width = 48;
-        bImg.height = 48;
-        bImg.style.imageRendering = "pixelated";
-        bImg.style.borderRadius = "50%";
-        blockieEl.appendChild(bImg);
-        $("export-privkey-title").textContent =
-            wallet.name + " \u2014 Address " + (state.selectedAddress + 1);
-        const exportAddrContainer = $("export-privkey-dot").parentElement;
-        exportAddrContainer.innerHTML = renderAddressHtml(addr.address);
-        attachCopyHandlers(exportAddrContainer);
-        $("export-privkey-password").value = "";
-        $("export-privkey-flash").textContent = "";
-        $("export-privkey-flash").style.visibility = "hidden";
-        $("export-privkey-password-section").classList.remove("hidden");
-        $("export-privkey-result").classList.add("hidden");
-        $("export-privkey-value").textContent = "";
-        showView("export-privkey");
+        // No pushCurrentView() here: exportPrivkey.show() can return
+        // without navigating, so it does its own push.
+        exportPrivkey.show(state.selectedWallet, state.selectedAddress);
     });
 
-    $("btn-export-privkey-confirm").addEventListener("click", async () => {
-        const password = $("export-privkey-password").value;
-        if (!password) {
-            $("export-privkey-flash").textContent = "Password is required.";
-            $("export-privkey-flash").style.visibility = "visible";
-            return;
-        }
-        const btn = $("btn-export-privkey-confirm");
-        btn.disabled = true;
-        btn.classList.add("text-muted");
-        const wallet = state.wallets[state.selectedWallet];
-        try {
-            const secret = await decryptWithPassword(
-                wallet.encryptedSecret,
-                password,
-            );
-            const signer = getSignerForAddress(
-                wallet,
-                state.selectedAddress,
-                secret,
-            );
-            const privateKey = signer.privateKey;
-            $("export-privkey-password-section").classList.add("hidden");
-            $("export-privkey-value").textContent = privateKey;
-            $("export-privkey-result").classList.remove("hidden");
-            $("export-privkey-flash").style.visibility = "hidden";
-        } catch {
-            $("export-privkey-flash").textContent = "Wrong password.";
-            $("export-privkey-flash").style.visibility = "visible";
-        } finally {
-            btn.disabled = false;
-            btn.classList.remove("text-muted");
-        }
-    });
-
-    $("export-privkey-value").addEventListener("click", () => {
-        const key = $("export-privkey-value").textContent;
-        if (key) {
-            navigator.clipboard.writeText(key);
-            showFlash("Copied!");
-            flashCopyFeedback($("export-privkey-value"));
-        }
-    });
-
-    $("btn-export-privkey-back").addEventListener("click", () => {
-        $("export-privkey-value").textContent = "";
-        $("export-privkey-password").value = "";
-        goBack();
-    });
+    exportPrivkey.init();
 }
 
 module.exports = { init, show };

src/popup/views/approval.js

@@ -7,6 +7,7 @@ const {
     hideError,
     renderAddressHtml,
     attachCopyHandlers,
+    onViewLeave,
 } = require("./helpers");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const {
@@ -461,7 +462,24 @@ function findActiveWallet() {
     return null;
 }
 
+// Drop the password from the DOM when either approval screen is left. The
+// approval window navigates on after a signature — approve-tx goes to the
+// wait screen — and the password must not sit in the hidden view for the
+// life of that window.
+function clearTxPassword() {
+    $("approve-tx-password").value = "";
+    hideError("approve-tx-error");
+}
+
+function clearSignPassword() {
+    $("approve-sign-password").value = "";
+    hideError("approve-sign-error");
+}
+
 function init(ctx) {
+    onViewLeave("approve-tx", clearTxPassword);
+    onViewLeave("approve-sign", clearSignPassword);
+
     $("approve-remember").addEventListener("change", async () => {
         state.rememberSiteChoice = $("approve-remember").checked;
         await saveState();

src/popup/views/confirmTx.js

@@ -21,6 +21,7 @@ const {
     renderAddressHtml,
     attachCopyHandlers,
     goBack,
+    onViewLeave,
 } = require("./helpers");
 const { state, currentNetwork } = require("../../shared/state");
 const { getSignerForAddress } = require("../../shared/wallet");
@@ -390,7 +391,17 @@ async function checkRecipientHistory(txInfo) {
     }
 }
 
+// Drop the password from the DOM. Registered as the view-leave handler so
+// it does not sit in the hidden view once the screen navigates on — to the
+// wait screen after a send, or anywhere else the user goes.
+function clearPassword() {
+    $("confirm-tx-password").value = "";
+    hideError("confirm-tx-password-error");
+}
+
 function init(ctx) {
+    onViewLeave("confirm-tx", clearPassword);
+
     $("btn-confirm-send").addEventListener("click", async () => {
         const password = $("confirm-tx-password").value;
         if (!password) {

src/popup/views/deleteWallet.js

@@ -1,4 +1,11 @@
-const { $, showView, showFlash, goBack, clearViewStack } = require("./helpers");
+const {
+    $,
+    showView,
+    showFlash,
+    goBack,
+    clearViewStack,
+    onViewLeave,
+} = require("./helpers");
 const { state, saveState } = require("../../shared/state");
 const { decryptWithPassword } = require("../../shared/vault");
 const {
@@ -9,22 +16,34 @@ const {
 let deleteWalletIndex = null;
 let ctx = null;
 
+// Drop the password from the DOM and the wallet selection from the
+// closure. Registered as the view-leave handler as well as run on entry,
+// so the typed password does not sit in the hidden view after the user
+// navigates away by any route, including the Settings gear.
+function clear() {
+    deleteWalletIndex = null;
+    $("delete-wallet-password").value = "";
+    $("delete-wallet-flash").textContent = "";
+    $("delete-wallet-flash").style.visibility = "hidden";
+}
+
 function show(walletIdx) {
+    clear();
     deleteWalletIndex = walletIdx;
     const wallet = state.wallets[walletIdx];
     $("delete-wallet-name").textContent =
         wallet.name || "Wallet " + (walletIdx + 1);
-    $("delete-wallet-password").value = "";
-    $("delete-wallet-flash").textContent = "";
-    $("delete-wallet-flash").style.visibility = "hidden";
     showView("delete-wallet-confirm");
 }
 
 function init(_ctx) {
     ctx = _ctx;
 
+    onViewLeave("delete-wallet-confirm", clear);
+
+    // No wipe here: goBack() routes through showView(), which runs the
+    // leave hook.
     $("btn-delete-wallet-back").addEventListener("click", () => {
-        deleteWalletIndex = null;
         goBack();
     });
 

src/popup/views/exportPrivkey.js

@@ -0,0 +1,174 @@
+// Private key export for a single address.
+//
+// The key controls the address outright — anyone holding it can move every
+// token in it, from any device, forever — so this screen is handled under
+// the same rules as the recovery phrase screen (./showPhrase.js):
+//
+//   1. Nothing is decrypted, no key is derived, and nothing is written into
+//      the DOM until decryptWithPassword has accepted the password.
+//   2. Leaving the screen by any path wipes it, via the onViewLeave hook,
+//      and a decrypt still in flight when that happens is discarded
+//      instead of written (revealGeneration).
+//   3. The key never reaches the logger. This module deliberately does not
+//      import src/shared/log.js.
+//
+// The key is also never assigned to `state`, so it cannot be persisted to
+// extension storage, and "export-privkey" is excluded from RESTORABLE_VIEWS
+// so the popup can never reopen onto it.
+
+const {
+    $,
+    showView,
+    showFlash,
+    flashCopyFeedback,
+    goBack,
+    onViewLeave,
+    pushCurrentView,
+    renderAddressHtml,
+    attachCopyHandlers,
+} = require("./helpers");
+const { state } = require("../../shared/state");
+const { decryptWithPassword } = require("../../shared/vault");
+const { getSignerForAddress } = require("../../shared/wallet");
+const makeBlockie = require("ethereum-blockies-base64");
+
+const VIEW = "export-privkey";
+
+let walletIndex = null;
+let addressIndex = null;
+
+// Bumped by every clear(), which is what leaving the screen runs. reveal()
+// captures it before awaiting the decrypt and refuses to touch the DOM if
+// it has moved: a decrypt still in flight when the screen is left would
+// otherwise write the key *after* the wipe, with nothing scheduled to wipe
+// it again, leaving it in the hidden view for the life of the popup.
+let revealGeneration = 0;
+
+// True only if the reveal that captured `generation` is still the live one:
+// the screen has not been left, cleared, or re-entered for another address
+// since it started.
+function isCurrentReveal(generation) {
+    return (
+        generation === revealGeneration &&
+        walletIndex !== null &&
+        addressIndex !== null &&
+        state.currentView === VIEW
+    );
+}
+
+function fail(message) {
+    $("export-privkey-flash").textContent = message;
+    $("export-privkey-flash").style.visibility = "visible";
+}
+
+// Wipe every trace of the key and drop the address selection. Safe to call
+// when nothing was ever revealed, and safe to call twice.
+function clear() {
+    walletIndex = null;
+    addressIndex = null;
+    revealGeneration += 1;
+    $("export-privkey-value").textContent = "";
+    $("export-privkey-password").value = "";
+    $("export-privkey-result").classList.add("hidden");
+    $("export-privkey-password-section").classList.remove("hidden");
+    $("export-privkey-flash").textContent = "";
+    $("export-privkey-flash").style.visibility = "hidden";
+}
+
+function show(walletIdx, addrIdx) {
+    const wallet = state.wallets[walletIdx];
+    const addr = wallet && wallet.addresses[addrIdx];
+    if (!addr) {
+        showFlash("That address is no longer available.");
+        return;
+    }
+    clear();
+    walletIndex = walletIdx;
+    addressIndex = addrIdx;
+
+    const blockieEl = $("export-privkey-jazzicon");
+    blockieEl.innerHTML = "";
+    const img = document.createElement("img");
+    img.src = makeBlockie(addr.address);
+    img.width = 48;
+    img.height = 48;
+    img.style.imageRendering = "pixelated";
+    img.style.borderRadius = "50%";
+    blockieEl.appendChild(img);
+
+    $("export-privkey-title").textContent =
+        wallet.name + " — Address " + (addrIdx + 1);
+    const addrContainer = $("export-privkey-dot").parentElement;
+    addrContainer.innerHTML = renderAddressHtml(addr.address);
+    attachCopyHandlers(addrContainer);
+
+    // Pushed here rather than by the caller: this function can return
+    // without navigating, and a push that happened anyway would leave an
+    // entry on the stack that no screen transition matches.
+    pushCurrentView();
+    showView(VIEW);
+}
+
+async function reveal() {
+    const password = $("export-privkey-password").value;
+    if (!password) {
+        fail("Password is required.");
+        return;
+    }
+    if (walletIndex === null) {
+        fail("No address is selected.");
+        return;
+    }
+    const wallet = state.wallets[walletIndex];
+
+    const btn = $("btn-export-privkey-confirm");
+    btn.disabled = true;
+    btn.classList.add("text-muted");
+    const generation = revealGeneration;
+    try {
+        const secret = await decryptWithPassword(
+            wallet.encryptedSecret,
+            password,
+        );
+        // The only suspension point in this view, and the gate on the only
+        // place a secret is written: if the screen was left while the
+        // decrypt ran, the wipe has already happened, so the key is not
+        // even derived, let alone written.
+        if (!isCurrentReveal(generation)) return;
+        const signer = getSignerForAddress(wallet, addressIndex, secret);
+        $("export-privkey-password").value = "";
+        $("export-privkey-password-section").classList.add("hidden");
+        $("export-privkey-value").textContent = signer.privateKey;
+        $("export-privkey-result").classList.remove("hidden");
+        $("export-privkey-flash").textContent = "";
+        $("export-privkey-flash").style.visibility = "hidden";
+    } catch {
+        if (!isCurrentReveal(generation)) return;
+        fail("That password is not correct. Please try again.");
+    } finally {
+        btn.disabled = false;
+        btn.classList.remove("text-muted");
+    }
+}
+
+function init() {
+    onViewLeave(VIEW, clear);
+
+    // No wipe here: goBack() routes through showView(), which runs the
+    // leave hook. A per-button wipe would only cover this one path.
+    $("btn-export-privkey-back").addEventListener("click", () => {
+        goBack();
+    });
+
+    $("btn-export-privkey-confirm").addEventListener("click", reveal);
+
+    $("export-privkey-value").addEventListener("click", () => {
+        const key = $("export-privkey-value").textContent;
+        if (!key) return;
+        navigator.clipboard.writeText(key);
+        showFlash("Copied!");
+        flashCopyFeedback($("export-privkey-value"));
+    });
+}
+
+module.exports = { init, show };