security: decrypt and sign dApp approvals in the popup (closes #157 )

The dApp transaction and signature approval paths sent the user's plaintext password to the background over runtime.sendMessage and decrypted there. Both now decrypt in the popup, where the password is typed, and put only the signed artifact on the wire: the raw signed transaction, or the signature. Neither the password, the recovery phrase, the xprv nor the private key crosses the messaging boundary any more. This matches what the popup-side eth_sendTransaction path in confirmTx.js already did. The popup runs the same sequence ethers' own sendTransaction() runs internally (populateTransaction, then signTransaction), so nonce, gas, fee and chain id population are unchanged. The background keeps broadcast and approval resolution, and when the popup cannot produce an artifact it reports the error over the same message so the requesting page still gets a failure rather than hanging. Moving the secret out of the background must not turn the background into a blind relay, so it re-derives the signer from the artifact and checks it against the approval it is holding before acting: shared/approvalVerify.js asserts that a raw transaction is the approved transaction signed by the approved address, and that a signature covers the approved payload and recovers to the approved address. A wrong password is now caught in the popup before anything is sent, so it fails with an inline full-sentence error and leaves the pending approval alive to retry; previously it reached the background and destroyed the approval. Rejection still resolves with EIP-1193 code 4001, and approvals still survive popup close and reopen. Removes the four standing TODO(security) markers, now that the flaw is gone.
feat: add About well to settings with build info and debug easter egg (#145 )
2026-08-09 02:50:50 +00:00 · 2026-07-26 18:39:09 +02:00
18 changed files with 1009 additions and 2461 deletions
--- a/.dockerignore
+++ b/.dockerignore
@@ -1,4 +1,3 @@
-.git
 node_modules
 .DS_Store
 dist
--- a/TODO.md
+++ b/TODO.md
@@ -23,6 +23,10 @@ get review, merge to main.

 # Completed Steps

+- 2026-08-09: dApp approval signing moved into the popup — the password no
+  longer crosses the extension messaging boundary; the background broadcasts and
+  resolves approvals only, and verifies the signed artifact against the approval
+  it holds (#157).
 - 2026-07-07 Adopted scripts-to-rule-them-all: `script/` entrypoints, Makefile
  shims, README Entrypoints section
 - 2026-03-01: About well in settings with build info and easter egg (in flight
--- a/build.js
+++ b/build.js
@@ -11,9 +11,51 @@ function ensureDir(dir) {
    fs.mkdirSync(dir, { recursive: true });
 }

+function getBuildInfo() {
+    const pkg = JSON.parse(
+        fs.readFileSync(path.join(__dirname, "package.json"), "utf8"),
+    );
+    let commitHash = "unknown";
+    try {
+        commitHash = execSync("git rev-parse --short HEAD", {
+            encoding: "utf8",
+        }).trim();
+    } catch (_) {
+        // not a git repo or git not available
+    }
+    let commitHashFull = "unknown";
+    try {
+        commitHashFull = execSync("git rev-parse HEAD", {
+            encoding: "utf8",
+        }).trim();
+    } catch (_) {
+        // not a git repo or git not available
+    }
+    return {
+        version: pkg.version,
+        license: pkg.license,
+        author: pkg.author,
+        commitHash,
+        commitHashFull,
+        buildDate: new Date().toISOString().slice(0, 10),
+    };
+}
+
 async function build() {
    console.log("Building AutistMask extension...");

+    const buildInfo = getBuildInfo();
+    console.log("Build info:", buildInfo);
+
+    const define = {
+        __BUILD_VERSION__: JSON.stringify(buildInfo.version),
+        __BUILD_LICENSE__: JSON.stringify(buildInfo.license),
+        __BUILD_AUTHOR__: JSON.stringify(buildInfo.author),
+        __BUILD_COMMIT__: JSON.stringify(buildInfo.commitHash),
+        __BUILD_COMMIT_FULL__: JSON.stringify(buildInfo.commitHashFull),
+        __BUILD_DATE__: JSON.stringify(buildInfo.buildDate),
+    };
+
    // compile tailwind CSS
    console.log("Compiling Tailwind CSS...");
    const tailwindInput = path.join(SRC, "popup", "styles", "main.css");
@@ -38,6 +80,7 @@ async function build() {
            platform: "browser",
            target: ["chrome110", "firefox110"],
            minify: true,
+            define,
        });

        // bundle background script
@@ -49,6 +92,7 @@ async function build() {
            platform: "browser",
            target: ["chrome110", "firefox110"],
            minify: true,
+            define,
        });

        // bundle content script
@@ -60,6 +104,7 @@ async function build() {
            platform: "browser",
            target: ["chrome110", "firefox110"],
            minify: true,
+            define,
        });

        // bundle inpage script (injected into page context, separate file)
@@ -71,6 +116,7 @@ async function build() {
            platform: "browser",
            target: ["chrome110", "firefox110"],
            minify: true,
+            define,
        });

        // copy popup HTML
--- a/scripts/apply-enrichment.mjs
+++ b/scripts/apply-enrichment.mjs
@@ -1,161 +0,0 @@
-#!/usr/bin/env node
-// Apply enrichment data to tokenList.js: add name + url fields to each token.
-
-import { readFileSync, writeFileSync } from "fs";
-
-const enrichment = JSON.parse(
-    readFileSync("scripts/token-enrichment.json", "utf8"),
-);
-
-// Well-known URLs for major tokens not in ethereum-lists.
-// These are official project websites verified from public sources.
-const EXTRA_URLS = {
-    "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2": "https://weth.io",
-    "0xdAC17F958D2ee523a2206206994597C13D831ec7": "https://tether.to",
-    "0xB8c77482e45F1F44dE1745F52C74426C631bDD52": "https://www.bnbchain.org",
-    "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48": "https://www.circle.com/usdc",
-    "0xdC035D45d973E3EC169d2276DDab16f1e407384F": "https://sky.money",
-    "0x2AF5D2aD76741191D15Dfe7bF6aC92d4Bd912Ca3": "https://www.bitfinex.com",
-    "0x514910771AF9Ca656af840dff83E8264EcF986CA": "https://chain.link",
-    "0x4c9EDD5852cd905f086C759E8383e09bff1E68B3": "https://ethena.fi",
-    "0x8d0D000Ee44948FC98c9B98A4FA4921476f08B0d":
-        "https://www.worldlibertyfinancial.com",
-    "0x6B175474E89094C44Da98b954EedeAC495271d0F": "https://makerdao.com",
-    "0x6c3ea9036406852006290770BEdFcAbA0e23A0e8":
-        "https://www.paypal.com/us/digital-wallet/manage-money/crypto/pyusd",
-    "0x95aD61b0a150d79219dCF64E1E6Cc01f0B64C4cE": "https://shibatoken.com",
-    "0xdA5e1988097297dCdc1f90D4dFE7909e847CBeF6":
-        "https://www.worldlibertyfinancial.com",
-    "0xA0b73E1Ff0B80914AB6fe0444E65848C4C34450b": "https://crypto.com",
-    "0x582d872A1B094FC48F5DE31D3B73F2D9bE47def1": "https://ton.org",
-    "0x68749665FF8D2d112Fa859AA293F07A622782F38": "https://gold.tether.to",
-    "0x196C20DA81Fbc324EcdF55501e95Ce9f0bD84d14": "https://polkadot.network",
-    "0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984": "https://uniswap.org",
-    "0x45804880De22913dAFE09f4980848ECE6EcbAf78":
-        "https://www.paxos.com/paxgold",
-    "0x3c3a81e81dc49A522A592e7622A7E711c06bf354": "https://www.mantle.xyz",
-    "0x7Fc66500c84A76Ad7e9c93437bFc5Ac33E2DDaE9": "https://aave.com",
-    "0x75231F58b43240C9718Dd58B4967c5114342a86c": "https://www.okx.com",
-    "0x6982508145454Ce325dDbE47a25d4ec3d2311933": "https://www.pepe.vip",
-    "0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599": "https://wbtc.network",
-    "0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84": "https://lido.fi",
-    "0x5A98FcBEA516Cf06857215779Fd812CA3beF1B32": "https://lido.fi",
-    "0xC18360217D8F7Ab5e7c516566761Ea12Ce7F9D72": "https://ens.domains",
-    "0x7D1AfA7B718fb893dB30A3aBc0Cfc608AaCfeBB0": "https://polygon.technology",
-    "0x9f8F72aA9304c8B593d555F12eF6589cC3A579A2": "https://makerdao.com",
-    "0xD533a949740bb3306d119CC777fa900bA034cd52": "https://curve.fi",
-    "0x111111111117dC0aa78b770fA6A738034120C302": "https://1inch.io",
-    "0x163f8C2467924be0ae7B5347228CABF260318753": "https://worldcoin.org",
-    "0xba100000625a3754423978a60c9317c58a424e3D": "https://balancer.fi",
-    "0xC011a73ee8576Fb46F5E1c5751cA3B9Fe0af2a6F": "https://synthetix.io",
-    "0x1a7e4e63778B4f12a199C062f3eFdD288afCBce8": "https://www.euler.finance",
-    "0xBBbbCA6A901c926F240b89EacB641d8Aec7AEafD": "https://loopring.org",
-    "0xC669928185DbCE49d2230CC9B0979BE6DC797957": "https://bitstable.finance",
-    "0x7f39C581F595B53c5cb19bD0b3f8dA6c935E2Ca0": "https://lido.fi",
-    "0xBe9895146f7AF43049ca1c1AE358B0541Ea49704":
-        "https://www.coinbase.com/cbeth",
-    "0xfAbA6f8e4a5E8Ab82F62fe7C39859FA577269BE3": "https://ondo.finance",
-    "0x0C10bF8FcB7Bf5412187A595ab97a3609160b5c6": "https://decentraland.org",
-    "0x6De037ef9aD2725EB40118Bb1702EBb27e4Aeb24": "https://www.render.com",
-    "0x4a220E6096B25EADb88358cb44068A3248254675": "https://www.quant.network",
-    "0xba5BDe662c17e2aDFF1075610382B9B691296350": "https://superrare.com",
-    "0x15D4c048F83bd7e37d49eA4C83a07267Ec4203dA": "https://galxe.com",
-    "0xc00e94Cb662C3520282E6f5717214004A7f26888": "https://compound.finance",
-    "0xE41d2489571d322189246DaFA5ebDe1F4699F498": "https://0x.org",
-    "0x0bc529c00C6401aEF6D220BE8C6Ea1667F6Ad93e": "https://yearn.fi",
-    "0x6fB3e0A217407EFFf7Ca062D46c26E5d60a14d69": "https://iotex.io",
-    "0xD31a59c85aE9D8edEFec411D448f90841571b89c": "https://solana.com",
-    "0xa1faa113cbE53436Df28FF0aEe54275c13B40975": "https://alphafinance.io",
-    "0xF57e7e7C23978C3cAEC3C3548E3D615c346e79fF": "https://immutable.com",
-    "0x0f5D2fB29fb7d3CFeE444a200298f468908cC942": "https://decentraland.org",
-    "0x3845badAde8e6dFF049820680d1F14bD3903a5d0": "https://www.sandbox.game",
-    "0x4d224452801ACEd8B2F0aebE155379bb5D594381": "https://apecoin.com",
-    "0x6810e776880C02933D47DB1b9fc05908e5386b96": "https://gnosis.io",
-    "0x5f98805A4E8be255a32880FDeC7F6728C6568bA0": "https://www.liquity.org",
-    "0xd26114cd6EE289AccF82350c8d8487fedB8A0C07": "https://omg.network",
-    "0x0D8775F648430679A709E98d2b0Cb6250d2887EF":
-        "https://basicattentiontoken.org",
-    "0xc944E90C64B2c07662A292be6244BDf05Cda44a7": "https://thegraph.com",
-    "0x1985365e9f78359a9B6AD760e32412f4a445E862": "https://augur.net",
-    "0x4E15361FD6b4BB609Fa63C81A2be19d873717870": "https://fantom.foundation",
-    "0x853d955aCEf822Db058eb8505911ED77F175b99e": "https://frax.finance",
-    "0x0000000000085d4780B73119b644AE5ecd22b376": "https://www.trueusd.com",
-    "0x0cEC1A9154Ff802e7934Fc916Ed7Ca50bDE6844e": "https://polymesh.network",
-    "0x956F47F50A910163D8BF957Cf5846D573E7f87CA": "https://fei.money",
-    "0x3432B6A60D23Ca0dFCa7761B7ab56459D9C964D0": "https://frax.finance",
-    "0xf939E0A03FB07F59A73314E73794Be0E57ac1b4E": "https://curve.fi",
-    "0x0100546F2cD4C9D97f798fFC9755E47865FF7Ee6": "https://alchemix.fi",
-    "0x808507121B80c02388fAd14726482e061B8da827": "https://pendle.finance",
-    "0xCa14007Eff0dB1f8135f4C25B34De49AB0d42766": "https://starknet.io",
-    "0x8457CA5040ad67fdebbCC8EdCE889A335Bc0fbFB": "https://alt.layer",
-    "0x4C19596f5aAfF459fA38B0f7eD92F11AE6543784": "https://www.truflation.com",
-    "0xB50721BCf8d664c30412Cfbc6cf7a15145234ad1": "https://arbitrum.io",
-    "0x912CE59144191C1204E64559FE8253a0e49E6548": "https://arbitrum.io",
-    "0x6985884C4392D348587B19cb9eAAf157F13271cd": "https://layerzero.network",
-    "0xFe0c30065B384F05761f15d0CC899D4F9F9Cc0eB": "https://ethfi.org",
-    "0x18084fbA666a33d37592fA2633fD49a74DD93a88": "https://tbtc.network",
-    "0x9D39A5DE30e57443BfF2A8307A4256c8797A3497": "https://suilend.fi",
-    "0x5283D291DBCF85356A21bA090E6db59121208b44": "https://blur.io",
-    "0x43Dfc4159D86F3A37A5A4B3D4580b888ad7d4DDd": "https://dydx.exchange",
-    "0xCf0C122c6b73ff809C693DB761e7BaeBe62b6a2E": "https://floki.com",
-    "0xe53EC727dbDEB9E2d5456c3be40cFF031AB40A55": "https://superfarm.com",
-    "0x32353A6C91143bfd6C7d363B546e62a9A2489A20": "https://www.agora.finance",
-    "0x1aBaEA1f7C830bD89Acc67eC4af516284b1bC33c": "https://www.euro-coin.com",
-    "0x1a03eF3d1a80b5f214e468ACD97F55714E049393": "https://gemspad.io",
-    "0x7122985656e38BDC0302Db86685bb972b145bD3C": "https://stone.fi",
-    "0xa35923162C49cF95e6BF26623385eb431ad920D3": "https://www.turbo-eth.com",
-    "0xdBdb4d16EdA451D0503b854CF79D55697F90c8DF": "https://alchemix.fi",
-    "0x08c32b0726C5684024ea6e141C50aDe9690bBdcc": "https://stratis.io",
-    "0x65Ef703f5594D2573eb71Aaf55BC0CB548492df4": "https://multichain.org",
-    "0x1151CB3d861920e07a38e03eEAd12C32178567F6": "https://bonk.com",
-    "0x090185f2135308BaD17527004364eBcC2D37e5F6": "https://spell.club",
-    "0xAf5191B0De278C7286d6C7CC6ab6BB8A73bA2Cd6": "https://stargate.finance",
-};
-
-// Apply extra URLs where enrichment has none
-for (const [addr, url] of Object.entries(EXTRA_URLS)) {
-    const e = enrichment[addr];
-    if (e && !e.url) {
-        e.url = url;
-    }
-}
-
-// Read original tokenList.js
-const original = readFileSync("src/shared/tokenList.js", "utf8");
-
-// Replace each token block: add name and url after decimals
-let result = original;
-let replacements = 0;
-
-for (const [addr, data] of Object.entries(enrichment)) {
-    // Escape special regex characters in the address
-    const escaped = addr.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
-
-    // Match the token block: { address: "...", symbol: "...", decimals: N, }
-    // The closing }, may have trailing whitespace
-    const blockRe = new RegExp(
-        `(\\{\\s*address:\\s*"${escaped}",\\s*symbol:\\s*"[^"]+",\\s*decimals:\\s*\\d+),?(\\s*\\})`,
-    );
-
-    const match = result.match(blockRe);
-    if (!match) {
-        console.error(`WARNING: Could not find block for ${addr}`);
-        continue;
-    }
-
-    // Build replacement: original fields + name + url
-    const nameEscaped = data.name.replace(/\\/g, "\\\\").replace(/"/g, '\\"');
-    const urlEscaped = data.url.replace(/\\/g, "\\\\").replace(/"/g, '\\"');
-    const replacement =
-        match[1] +
-        `,\n        name: "${nameEscaped}",` +
-        `\n        url: "${urlEscaped}",` +
-        match[2];
-
-    result = result.replace(blockRe, replacement);
-    replacements++;
-}
-
-console.error(`Applied ${replacements} enrichments to tokenList.js`);
-writeFileSync("src/shared/tokenList.js", result);
-console.error("Done!");
--- a/scripts/enrich-tokens.mjs
+++ b/scripts/enrich-tokens.mjs
@@ -1,87 +0,0 @@
-#!/usr/bin/env node
-// Temporary script: fetch name + homepage URL for every token in tokenList.js
-// Phase 1: CoinGecko /coins/list (1 bulk call) for names — gets 100%
-// Phase 2: ethereum-lists GitHub repo for project URLs — gets ~15%
-
-import { readFileSync, writeFileSync } from "fs";
-
-const src = readFileSync("src/shared/tokenList.js", "utf8");
-
-const tokens = [];
-const re =
-    /\{\s*address:\s*"(0x[a-fA-F0-9]{40})",\s*symbol:\s*"([^"]+)",\s*decimals:\s*(\d+)/g;
-let m;
-while ((m = re.exec(src)) !== null) {
-    tokens.push({ address: m[1], symbol: m[2], decimals: parseInt(m[3]) });
-}
-console.error(`Parsed ${tokens.length} tokens`);
-
-const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
-
-// --- Phase 1: bulk names from CoinGecko ---
-console.error("Fetching CoinGecko coins list...");
-const listResp = await fetch(
-    "https://api.coingecko.com/api/v3/coins/list?include_platform=true",
-);
-if (!listResp.ok) throw new Error(`CoinGecko list HTTP ${listResp.status}`);
-const coins = await listResp.json();
-
-const addrMap = new Map();
-for (const coin of coins) {
-    const eth = (coin.platforms?.ethereum || "").toLowerCase().trim();
-    if (eth && eth.startsWith("0x")) {
-        addrMap.set(eth, { name: coin.name, id: coin.id });
-    }
-}
-console.error(`CoinGecko map: ${addrMap.size} Ethereum tokens`);
-
-const enriched = new Map();
-for (const t of tokens) {
-    const info = addrMap.get(t.address.toLowerCase());
-    enriched.set(t.address, { name: info?.name || t.symbol, url: "" });
-}
-console.error(
-    `Matched ${[...enriched.values()].filter((e) => e.name).length}/${tokens.length} names`,
-);
-
-// --- Phase 2: ethereum-lists GitHub for URLs ---
-console.error("Fetching URLs from ethereum-lists GitHub...");
-const CONCURRENT = 10;
-let urlsFound = 0;
-
-for (let i = 0; i < tokens.length; i += CONCURRENT) {
-    const batch = tokens.slice(i, i + CONCURRENT);
-    await Promise.allSettled(
-        batch.map(async (t) => {
-            try {
-                const r = await fetch(
-                    `https://raw.githubusercontent.com/ethereum-lists/tokens/master/tokens/eth/${t.address}.json`,
-                );
-                if (!r.ok) return;
-                const data = await r.json();
-                const website = (data.website || "").trim();
-                if (website && website !== "https://") {
-                    enriched.get(t.address).url = website;
-                    urlsFound++;
-                }
-            } catch {
-                // ignore
-            }
-        }),
-    );
-    if (i % 100 === 0) {
-        console.error(
-            `  GitHub: ${Math.min(i + CONCURRENT, tokens.length)}/${tokens.length}, ${urlsFound} URLs`,
-        );
-    }
-    await sleep(200);
-}
-console.error(`Phase 2 done: ${urlsFound} URLs from ethereum-lists`);
-
-// --- Output ---
-const output = {};
-for (const [addr, e] of enriched) {
-    output[addr] = { name: e.name, url: e.url };
-}
-writeFileSync("scripts/token-enrichment.json", JSON.stringify(output, null, 2));
-console.error(`Done! ${tokens.length} names, ${urlsFound} URLs.`);
--- a/scripts/token-enrichment.json
+++ b/scripts/token-enrichment.json
--- a/src/background/index.js
+++ b/src/background/index.js
@@ -5,7 +5,6 @@
 const { DEFAULT_RPC_URL } = require("../shared/constants");
 const { SUPPORTED_CHAIN_IDS, networkByChainId } = require("../shared/networks");
 const { onChainSwitch } = require("../shared/chainSwitch");
-const { getBytes } = require("ethers");
 const {
    state,
    loadState,
@@ -14,8 +13,7 @@ const {
 } = require("../shared/state");
 const { refreshBalances, getProvider } = require("../shared/balances");
 const { debugFetch } = require("../shared/log");
-const { decryptWithPassword } = require("../shared/vault");
-const { getSignerForAddress } = require("../shared/wallet");
+const { verifySignedTx, verifySignature } = require("../shared/approvalVerify");
 const {
    isPhishingDomain,
    updatePhishingList,
@@ -725,39 +723,28 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
            return true;
        }

+        // The popup signs; it reports back here when it could not. Fail the
+        // request the same way this handler used to when it did the signing.
+        if (msg.error) {
+            approval.resolve({ error: { message: msg.error } });
+            sendResponse({ error: msg.error });
+            return false;
+        }
+
        (async () => {
            try {
                await loadState();
                const activeAddress = await getActiveAddress();
-                let wallet, addrIndex;
-                for (const w of state.wallets) {
-                    for (let i = 0; i < w.addresses.length; i++) {
-                        if (w.addresses[i].address === activeAddress) {
-                            wallet = w;
-                            addrIndex = i;
-                            break;
-                        }
-                    }
-                    if (wallet) break;
-                }
-                if (!wallet) throw new Error("Wallet not found");
-                // TODO(security): Move decryption to popup to avoid sending password via runtime.sendMessage
-                let decrypted = await decryptWithPassword(
-                    wallet.encryptedSecret,
-                    msg.password,
+                // The popup holds the secret, but the background stays the
+                // authority on what is broadcast: the raw transaction must be
+                // the approved one, signed by the approved address.
+                verifySignedTx(
+                    msg.rawSignedTx,
+                    approval.txParams,
+                    activeAddress,
                );
-                const signer = getSignerForAddress(
-                    wallet,
-                    addrIndex,
-                    decrypted,
-                );
-                // Best-effort: clear decrypted secret after use.
-                // Note: JS strings are immutable; this nulls the reference but
-                // the original string may persist in memory until GC.
-                decrypted = null;
                const provider = getProvider(state.rpcUrl);
-                const connected = signer.connect(provider);
-                const tx = await connected.sendTransaction(approval.txParams);
+                const tx = await provider.broadcastTransaction(msg.rawSignedTx);
                approval.resolve({ txHash: tx.hash });
                sendResponse({ txHash: tx.hash });
            } catch (e) {
@@ -784,55 +771,23 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
            return true;
        }

+        // The popup signs; it reports back here when it could not. Fail the
+        // request the same way this handler used to when it did the signing.
+        if (msg.error) {
+            approval.resolve({ error: { message: msg.error } });
+            sendResponse({ error: msg.error });
+            return false;
+        }
+
        (async () => {
            try {
-                await loadState();
                const activeAddress = await getActiveAddress();
-                let wallet, addrIndex;
-                for (const w of state.wallets) {
-                    for (let i = 0; i < w.addresses.length; i++) {
-                        if (w.addresses[i].address === activeAddress) {
-                            wallet = w;
-                            addrIndex = i;
-                            break;
-                        }
-                    }
-                    if (wallet) break;
-                }
-                if (!wallet) throw new Error("Wallet not found");
-                // TODO(security): Move decryption to popup to avoid sending password via runtime.sendMessage
-                let decrypted = await decryptWithPassword(
-                    wallet.encryptedSecret,
-                    msg.password,
-                );
-                const signer = getSignerForAddress(
-                    wallet,
-                    addrIndex,
-                    decrypted,
-                );
-                // Best-effort: clear decrypted secret after use.
-                // Note: JS strings are immutable; this nulls the reference but
-                // the original string may persist in memory until GC.
-                decrypted = null;
-
-                const sp = approval.signParams;
-                let signature;
-
-                if (sp.method === "personal_sign" || sp.method === "eth_sign") {
-                    signature = await signer.signMessage(getBytes(sp.message));
-                } else {
-                    // eth_signTypedData_v4 / eth_signTypedData
-                    const typedData = JSON.parse(sp.typedData);
-                    const { domain, types, message } = typedData;
-                    // ethers handles EIP712Domain internally
-                    delete types.EIP712Domain;
-                    signature = await signer.signTypedData(
-                        domain,
-                        types,
-                        message,
-                    );
-                }
-
+                // The popup holds the secret, but the background stays the
+                // authority on what is handed back to the page: the signature
+                // must cover the approved payload and recover to the approved
+                // address.
+                const signature = msg.signature;
+                verifySignature(approval.signParams, signature, activeAddress);
                approval.resolve({ signature });
                sendResponse({ signature });
            } catch (e) {
--- a/src/popup/index.html
+++ b/src/popup/index.html
@@ -1002,6 +1002,64 @@
                    </p>
                    <div id="settings-denied-sites"></div>
                </div>
+
+                <div class="bg-well p-3 mx-1 mb-3">
+                    <h3 class="font-bold mb-1">About</h3>
+                    <p class="text-xs mb-2">
+                        <a
+                            href="https://git.eeqj.de/sneak/AutistMask"
+                            class="underline decoration-dashed"
+                            target="_blank"
+                            rel="noopener noreferrer"
+                            >AutistMask</a
+                        >
+                        — Minimal Ethereum wallet browser extension.
+                    </p>
+                    <div class="text-xs">
+                        <div class="mb-1">
+                            <span class="text-muted">License:</span>
+                            <span id="about-license"></span>
+                        </div>
+                        <div class="mb-1">
+                            <span class="text-muted">Author:</span>
+                            <span id="about-author"></span>
+                        </div>
+                        <div class="mb-1">
+                            <span class="text-muted">Version:</span>
+                            <span
+                                id="about-version"
+                                class="cursor-pointer select-none"
+                            ></span>
+                        </div>
+                        <div class="mb-1">
+                            <span class="text-muted">Release date:</span>
+                            <span id="about-release-date"></span>
+                        </div>
+                        <div>
+                            <span class="text-muted">Commit:</span>
+                            <a
+                                id="about-commit-link"
+                                class="underline decoration-dashed"
+                                target="_blank"
+                                rel="noopener noreferrer"
+                            ></a>
+                        </div>
+                    </div>
+                </div>
+
+                <div
+                    id="settings-debug-well"
+                    class="bg-well p-3 mx-1 mb-3"
+                    style="display: none"
+                >
+                    <h3 class="font-bold mb-1">Debug</h3>
+                    <label
+                        class="text-xs flex items-center gap-1 cursor-pointer"
+                    >
+                        <input type="checkbox" id="settings-debug-mode" />
+                        Enable debug mode
+                    </label>
+                </div>
            </div>

            <!-- ============ DELETE WALLET CONFIRM ============ -->
--- a/src/popup/index.js
+++ b/src/popup/index.js
@@ -1,18 +1,14 @@
 // AutistMask popup entry point.
 // Loads state, initializes views, triggers first render.

-const { DEBUG } = require("../shared/constants");
-const {
-    state,
-    saveState,
-    loadState,
-    currentNetwork,
-} = require("../shared/state");
+const { state, saveState, loadState } = require("../shared/state");
+const { setRuntimeDebug } = require("../shared/log");
 const { refreshPrices } = require("../shared/prices");
 const { refreshBalances } = require("../shared/balances");
 const {
    $,
    showView,
+    updateDebugBanner,
    setRenderMain,
    pushCurrentView,
    goBack,
@@ -209,21 +205,11 @@ async function init() {
    await loadState();
    applyTheme(state.theme);

-    const net = currentNetwork();
-    if (DEBUG || net.isTestnet) {
-        const banner = document.createElement("div");
-        banner.id = "debug-banner";
-        if (DEBUG && net.isTestnet) {
-            banner.textContent = "DEBUG / INSECURE [TESTNET]";
-        } else if (net.isTestnet) {
-            banner.textContent = "[TESTNET]";
-        } else {
-            banner.textContent = "DEBUG / INSECURE";
-        }
-        banner.style.cssText =
-            "background:#c00;color:#fff;text-align:center;font-size:10px;padding:1px 0;font-family:monospace;position:sticky;top:0;z-index:9999;";
-        document.body.prepend(banner);
-    }
+    // Sync runtime debug flag from persisted state before first render
+    setRuntimeDebug(state.debugMode);
+
+    // Create the debug/testnet banner if needed (uses runtime debug state)
+    updateDebugBanner();

    // Auto-default active address
    if (
--- a/src/popup/styles/main.css
+++ b/src/popup/styles/main.css
@@ -10,7 +10,7 @@
    --color-border: #000000;
    --color-border-light: #cccccc;
    --color-hover: #eeeeee;
-    --color-well: #f5f5f5;
+    --color-well: #e8e8e8;
    --color-danger-well: #fef2f2;
    --color-section: #dddddd;
 }
--- a/src/popup/views/approval.js
+++ b/src/popup/views/approval.js
@@ -9,10 +9,19 @@ const {
    attachCopyHandlers,
 } = require("./helpers");
 const { state, saveState, currentNetwork } = require("../../shared/state");
-const { formatEther, formatUnits, Interface, toUtf8String } = require("ethers");
+const {
+    formatEther,
+    formatUnits,
+    getBytes,
+    Interface,
+    toUtf8String,
+} = require("ethers");
 const { getPrice, formatUsd } = require("../../shared/prices");
 const { ERC20_ABI } = require("../../shared/constants");
 const { TOKEN_BY_ADDRESS } = require("../../shared/tokenList");
+const { decryptWithPassword } = require("../../shared/vault");
+const { getSignerForAddress } = require("../../shared/wallet");
+const { getProvider } = require("../../shared/balances");
 const txStatus = require("./txStatus");
 const uniswap = require("../../shared/uniswap");
 const runtime =
@@ -153,6 +162,8 @@ function showTxApproval(details) {
        details.isPhishingDomain,
    );

+    pendingTxParams = details.txParams;
+
    const toAddr = details.txParams.to;
    const token = toAddr ? TOKEN_BY_ADDRESS.get(toAddr.toLowerCase()) : null;
    const ethValue = formatEther(details.txParams.value || "0");
@@ -326,6 +337,7 @@ function showSignApproval(details) {
    );

    const sp = details.signParams;
+    pendingSignParams = sp;

    $("approve-sign-hostname").textContent = details.hostname;
    $("approve-sign-from").innerHTML = approvalAddressHtml(sp.from);
@@ -401,6 +413,36 @@ function show(id) {

 let approvalId = null;
 let pendingTxDetails = null;
+// The exact parameters shown to the user, kept so the popup signs what it
+// displayed rather than re-fetching anything at approval time. Both are
+// repopulated by show() when the popup is closed and reopened.
+let pendingTxParams = null;
+let pendingSignParams = null;
+
+// Approve buttons stay disabled and muted while the popup derives the key and
+// signs, which is slow enough (Argon2id) that a double click is likely.
+function setTxButtonBusy(busy) {
+    $("btn-approve-tx").disabled = busy;
+    $("btn-approve-tx").classList.toggle("text-muted", busy);
+}
+
+function setSignButtonBusy(busy) {
+    $("btn-approve-sign").disabled = busy;
+    $("btn-approve-sign").classList.toggle("text-muted", busy);
+}
+
+// Locate the wallet and the address index owning the currently active
+// address. Returns null when no wallet holds it.
+function findActiveWallet() {
+    for (const wallet of state.wallets) {
+        for (let i = 0; i < wallet.addresses.length; i++) {
+            if (wallet.addresses[i].address === state.activeAddress) {
+                return { wallet, addrIndex: i };
+            }
+        }
+    }
+    return null;
+}

 function init(ctx) {
    $("approve-remember").addEventListener("change", async () => {
@@ -430,25 +472,78 @@ function init(ctx) {
        window.close();
    });

-    $("btn-approve-tx").addEventListener("click", () => {
-        const password = $("approve-tx-password").value;
+    $("btn-approve-tx").addEventListener("click", async () => {
+        let password = $("approve-tx-password").value;
        if (!password) {
            showError("approve-tx-error", "Please enter your password.");
            return;
        }
        hideError("approve-tx-error");
-        $("btn-approve-tx").disabled = true;
-        $("btn-approve-tx").classList.add("text-muted");
+        setTxButtonBusy(true);

-        runtime.sendMessage(
-            {
+        const active = findActiveWallet();
+        if (!active) {
+            password = null;
+            showError(
+                "approve-tx-error",
+                "No wallet was found for the active address.",
+            );
+            setTxButtonBusy(false);
+            return;
+        }
+
+        // Decrypt here, in the popup. The password must never cross the
+        // extension messaging boundary; only the signed transaction does.
+        let decryptedSecret;
+        try {
+            decryptedSecret = await decryptWithPassword(
+                active.wallet.encryptedSecret,
+                password,
+            );
+        } catch {
+            showError(
+                "approve-tx-error",
+                "That password is incorrect. Please try again.",
+            );
+            setTxButtonBusy(false);
+            return;
+        } finally {
+            // Best-effort: drop the password as soon as the key derivation
+            // is done. Note that JS strings are immutable; this clears the
+            // reference but the original string may persist until GC.
+            password = null;
+        }
+
+        const payload = {
            type: "AUTISTMASK_TX_RESPONSE",
            id: approvalId,
            approved: true,
-                // TODO(security): Move decryption to popup to avoid sending password via runtime.sendMessage
-                password: password,
-            },
-            (response) => {
+        };
+        try {
+            const signer = getSignerForAddress(
+                active.wallet,
+                active.addrIndex,
+                decryptedSecret,
+            );
+            const provider = getProvider(state.rpcUrl);
+            const connected = signer.connect(provider);
+            // This is the sequence ethers' own sendTransaction() runs
+            // internally, so nonce, gas, fee and chain id population are
+            // identical to when the background did the signing.
+            const populated =
+                await connected.populateTransaction(pendingTxParams);
+            delete populated.from;
+            payload.rawSignedTx = await connected.signTransaction(populated);
+        } catch (e) {
+            payload.error =
+                e.shortMessage || e.message || "Transaction signing failed.";
+        } finally {
+            // Best-effort: clear the decrypted secret after use, with the
+            // same immutability caveat as the password above.
+            decryptedSecret = null;
+        }
+
+        runtime.sendMessage(payload, (response) => {
            if (response && response.txHash) {
                txStatus.showWait(pendingTxDetails, response.txHash);
            } else {
@@ -456,8 +551,7 @@ function init(ctx) {
                    (response && response.error) || "Transaction failed.";
                txStatus.showError(pendingTxDetails, null, msg);
            }
-            },
-        );
+        });
    });

    $("btn-reject-tx").addEventListener("click", () => {
@@ -469,36 +563,93 @@ function init(ctx) {
        window.close();
    });

-    $("btn-approve-sign").addEventListener("click", () => {
-        const password = $("approve-sign-password").value;
+    $("btn-approve-sign").addEventListener("click", async () => {
+        let password = $("approve-sign-password").value;
        if (!password) {
            showError("approve-sign-error", "Please enter your password.");
            return;
        }
        hideError("approve-sign-error");
-        $("btn-approve-sign").disabled = true;
-        $("btn-approve-sign").classList.add("text-muted");
+        setSignButtonBusy(true);

-        runtime.sendMessage(
-            {
+        const active = findActiveWallet();
+        if (!active) {
+            password = null;
+            showError(
+                "approve-sign-error",
+                "No wallet was found for the active address.",
+            );
+            setSignButtonBusy(false);
+            return;
+        }
+
+        // Decrypt here, in the popup. The password must never cross the
+        // extension messaging boundary; only the signature does.
+        let decryptedSecret;
+        try {
+            decryptedSecret = await decryptWithPassword(
+                active.wallet.encryptedSecret,
+                password,
+            );
+        } catch {
+            showError(
+                "approve-sign-error",
+                "That password is incorrect. Please try again.",
+            );
+            setSignButtonBusy(false);
+            return;
+        } finally {
+            // Best-effort: drop the password as soon as the key derivation
+            // is done. Note that JS strings are immutable; this clears the
+            // reference but the original string may persist until GC.
+            password = null;
+        }
+
+        const payload = {
            type: "AUTISTMASK_SIGN_RESPONSE",
            id: approvalId,
            approved: true,
-                // TODO(security): Move decryption to popup to avoid sending password via runtime.sendMessage
-                password: password,
-            },
-            (response) => {
+        };
+        try {
+            const signer = getSignerForAddress(
+                active.wallet,
+                active.addrIndex,
+                decryptedSecret,
+            );
+            const sp = pendingSignParams;
+            if (sp.method === "personal_sign" || sp.method === "eth_sign") {
+                payload.signature = await signer.signMessage(
+                    getBytes(sp.message),
+                );
+            } else {
+                // eth_signTypedData_v4 / eth_signTypedData
+                const typedData = JSON.parse(sp.typedData);
+                const { domain, types, message } = typedData;
+                // ethers handles EIP712Domain internally
+                delete types.EIP712Domain;
+                payload.signature = await signer.signTypedData(
+                    domain,
+                    types,
+                    message,
+                );
+            }
+        } catch (e) {
+            payload.error = e.shortMessage || e.message || "Signing failed.";
+        } finally {
+            // Best-effort: clear the decrypted secret after use, with the
+            // same immutability caveat as the password above.
+            decryptedSecret = null;
+        }
+
+        runtime.sendMessage(payload, (response) => {
            if (response && response.signature) {
                window.close();
            } else {
-                    const msg =
-                        (response && response.error) || "Signing failed.";
+                const msg = (response && response.error) || "Signing failed.";
                showError("approve-sign-error", msg);
-                    $("btn-approve-sign").disabled = false;
-                    $("btn-approve-sign").classList.remove("text-muted");
+                setSignButtonBusy(false);
            }
-            },
-        );
+        });
    });

    $("btn-reject-sign").addEventListener("click", () => {
--- a/src/popup/views/helpers.js
+++ b/src/popup/views/helpers.js
@@ -1,6 +1,6 @@
 // Shared DOM helpers used by all views.

-const { DEBUG } = require("../../shared/constants");
+const { isDebug } = require("../../shared/log");
 const {
    formatUsd,
    getPrice,
@@ -59,19 +59,37 @@ function showView(name) {
    clearFlash();
    state.currentView = name;
    saveState();
+    updateDebugBanner(name);
+}
+
+// Create or update the debug/insecure warning banner.
+// Called on every view switch and after the settings debug toggle changes.
+// The banner is shown when the compile-time DEBUG constant is true OR when
+// the user has enabled runtime debug mode via the settings easter egg, OR
+// when the active network is a testnet.
+function updateDebugBanner(viewName) {
+    const debug = isDebug();
    const net = currentNetwork();
-    if (DEBUG || net.isTestnet) {
-        const banner = document.getElementById("debug-banner");
-        if (banner) {
-            if (DEBUG && net.isTestnet) {
-                banner.textContent =
-                    "DEBUG / INSECURE [TESTNET] (" + name + ")";
+    const show = debug || net.isTestnet;
+    let banner = document.getElementById("debug-banner");
+    if (show) {
+        if (!banner) {
+            banner = document.createElement("div");
+            banner.id = "debug-banner";
+            banner.style.cssText =
+                "background:#c00;color:#fff;text-align:center;font-size:10px;padding:1px 0;font-family:monospace;position:sticky;top:0;z-index:9999;";
+            document.body.prepend(banner);
+        }
+        const suffix = viewName ? " (" + viewName + ")" : "";
+        if (debug && net.isTestnet) {
+            banner.textContent = "DEBUG / INSECURE [TESTNET]" + suffix;
        } else if (net.isTestnet) {
-                banner.textContent = "[TESTNET]";
+            banner.textContent = "[TESTNET]" + suffix;
        } else {
-                banner.textContent = "DEBUG / INSECURE (" + name + ")";
-            }
+            banner.textContent = "DEBUG / INSECURE" + suffix;
        }
+    } else if (banner) {
+        banner.remove();
    }
 }

@@ -417,6 +435,7 @@ module.exports = {
    showError,
    hideError,
    showView,
+    updateDebugBanner,
    setRenderMain,
    pushCurrentView,
    goBack,
--- a/src/popup/views/settings.js
+++ b/src/popup/views/settings.js
@@ -1,8 +1,10 @@
 const {
    $,
    showView,
+    updateDebugBanner,
    showFlash,
    escapeHtml,
+    flashCopyFeedback,
    goBack,
    pushCurrentView,
 } = require("./helpers");
@@ -10,12 +12,23 @@ const { applyTheme } = require("../theme");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const { NETWORKS, SUPPORTED_CHAIN_IDS } = require("../../shared/networks");
 const { onChainSwitch } = require("../../shared/chainSwitch");
-const { log, debugFetch } = require("../../shared/log");
+const { log, debugFetch, setRuntimeDebug } = require("../../shared/log");
 const deleteWallet = require("./deleteWallet");
+const {
+    BUILD_VERSION,
+    BUILD_LICENSE,
+    BUILD_AUTHOR,
+    BUILD_COMMIT,
+    BUILD_DATE,
+    GITEA_COMMIT_URL,
+} = require("../../shared/buildInfo");

 const runtime =
    typeof browser !== "undefined" ? browser.runtime : chrome.runtime;

+let versionClickCount = 0;
+let versionClickTimer = null;
+
 function renderSiteList(containerId, siteMap, stateKey) {
    const container = $(containerId);
    const hostnames = [...new Set(Object.values(siteMap).flat())];
@@ -142,6 +155,28 @@ function show() {
    renderSiteLists();
    renderWalletListSettings();

+    // Populate About well
+    $("about-license").textContent = BUILD_LICENSE;
+    // Show only the name part of the author field (strip email)
+    const authorName = BUILD_AUTHOR.replace(/\s*<[^>]+>/, "");
+    $("about-author").textContent = authorName;
+    $("about-version").textContent = BUILD_VERSION;
+    $("about-release-date").textContent = BUILD_DATE;
+    $("about-commit-link").textContent = BUILD_COMMIT;
+    $("about-commit-link").href = GITEA_COMMIT_URL;
+
+    // Reset version click counter each time settings opens
+    versionClickCount = 0;
+
+    // Show debug well if debug mode is already enabled
+    const debugWell = $("settings-debug-well");
+    if (state.debugMode) {
+        debugWell.style.display = "";
+    } else {
+        debugWell.style.display = "none";
+    }
+    $("settings-debug-mode").checked = state.debugMode;
+
    showView("settings");
 }

@@ -289,6 +324,66 @@ function init(ctx) {
        ctx.showSettingsAddTokenView,
    );

+    // Bright saturated colors for easter egg flashes (clicks 6–10)
+    const easterEggColors = [
+        "#ff0055", // hot pink
+        "#00cc44", // vivid green
+        "#3366ff", // electric blue
+        "#ff9900", // bright orange
+        "#aa00ff", // vivid purple
+    ];
+
+    // Easter egg: click version 10 times to reveal the debug well.
+    // Each click does a copy-flash animation. After 5 clicks, each
+    // additional click flashes a different bright saturated color.
+    $("about-version").addEventListener("click", () => {
+        versionClickCount++;
+        clearTimeout(versionClickTimer);
+        // Reset counter if user stops clicking for 3 seconds
+        versionClickTimer = setTimeout(() => {
+            versionClickCount = 0;
+        }, 3000);
+
+        const el = $("about-version");
+
+        if (versionClickCount > 5) {
+            // Colored flash for clicks 6–10
+            const colorIdx = versionClickCount - 6;
+            const color = easterEggColors[colorIdx % easterEggColors.length];
+            el.classList.remove("copy-flash-fade");
+            el.style.backgroundColor = color;
+            el.style.color = "#ffffff";
+            setTimeout(() => {
+                el.style.backgroundColor = "";
+                el.style.color = "";
+                el.classList.add("copy-flash-fade");
+                setTimeout(() => {
+                    el.classList.remove("copy-flash-fade");
+                }, 275);
+            }, 75);
+        } else {
+            // Standard copy-flash for clicks 1–5
+            flashCopyFeedback(el);
+        }
+
+        if (versionClickCount >= 10) {
+            versionClickCount = 0;
+            clearTimeout(versionClickTimer);
+            $("settings-debug-well").style.display = "";
+        }
+    });
+
+    // Debug mode toggle — update runtime flag, persist, and re-render banner
+    $("settings-debug-mode").addEventListener("change", async () => {
+        state.debugMode = $("settings-debug-mode").checked;
+        setRuntimeDebug(state.debugMode);
+        await saveState();
+        updateDebugBanner(state.currentView);
+    });
+
+    // Sync runtime debug flag on init
+    setRuntimeDebug(state.debugMode);
+
    $("btn-settings-back").addEventListener("click", () => {
        goBack();
    });
--- a/src/shared/approvalVerify.js
+++ b/src/shared/approvalVerify.js
@@ -0,0 +1,124 @@
+// Verification of the signed artifacts produced by the approval popup.
+//
+// Signing happens in the popup, where the password is entered; the background
+// only broadcasts the raw transaction and resolves the pending approval back
+// to the requesting page. So that moving the signing out of the background
+// does not turn the background into a blind relay, the background re-derives
+// the signer from the artifact and checks it against the approval it is
+// holding before acting on it. All recovery is delegated to ethers.
+//
+// Every failure message is a full sentence, because these strings are shown to
+// the user and returned to the dApp.
+
+const {
+    Transaction,
+    getAddress,
+    getBytes,
+    verifyMessage,
+    verifyTypedData,
+} = require("ethers");
+
+// Case-insensitive address comparison that tolerates absent values on either
+// side. Two absent addresses compare equal (contract creation has no `to`).
+function sameAddress(a, b) {
+    const aMissing = a === null || a === undefined || a === "";
+    const bMissing = b === null || b === undefined || b === "";
+    if (aMissing || bMissing) return aMissing && bMissing;
+    try {
+        return getAddress(a) === getAddress(b);
+    } catch {
+        return String(a).toLowerCase() === String(b).toLowerCase();
+    }
+}
+
+// Normalize a transaction value (hex string, decimal string, number or
+// bigint) to a bigint. An absent value is zero, matching ethers.
+function normalizeValue(v) {
+    if (v === null || v === undefined || v === "") return 0n;
+    return BigInt(v);
+}
+
+// Normalize call data to a lowercase hex string. Absent data is "0x".
+function normalizeData(v) {
+    if (v === null || v === undefined || v === "" || v === "0x") return "0x";
+    return String(v).toLowerCase();
+}
+
+// Assert that a raw signed transaction is the transaction the user approved,
+// signed by the address the approval was raised for. Returns the parsed
+// ethers Transaction on success, throws otherwise.
+function verifySignedTx(rawSignedTx, txParams, expectedFrom) {
+    if (typeof rawSignedTx !== "string" || !rawSignedTx.startsWith("0x")) {
+        throw new Error("The signed transaction is missing or malformed.");
+    }
+
+    let parsed;
+    try {
+        parsed = Transaction.from(rawSignedTx);
+    } catch {
+        throw new Error("The signed transaction could not be decoded.");
+    }
+
+    if (!parsed.from) {
+        throw new Error("The signed transaction carries no valid signature.");
+    }
+    if (!sameAddress(parsed.from, expectedFrom)) {
+        throw new Error(
+            "The signed transaction was signed by a different address than the one that was approved.",
+        );
+    }
+    if (!sameAddress(parsed.to, txParams.to)) {
+        throw new Error(
+            "The signed transaction does not go to the approved recipient.",
+        );
+    }
+    if (normalizeValue(parsed.value) !== normalizeValue(txParams.value)) {
+        throw new Error(
+            "The signed transaction does not carry the approved value.",
+        );
+    }
+    if (normalizeData(parsed.data) !== normalizeData(txParams.data)) {
+        throw new Error(
+            "The signed transaction does not carry the approved call data.",
+        );
+    }
+
+    return parsed;
+}
+
+// Assert that a signature over the approved message or typed data was
+// produced by the address the approval was raised for. Returns the recovered
+// address on success, throws otherwise.
+function verifySignature(signParams, signature, expectedFrom) {
+    if (typeof signature !== "string" || !signature.startsWith("0x")) {
+        throw new Error("The signature is missing or malformed.");
+    }
+
+    let recovered;
+    try {
+        if (
+            signParams.method === "personal_sign" ||
+            signParams.method === "eth_sign"
+        ) {
+            recovered = verifyMessage(getBytes(signParams.message), signature);
+        } else {
+            const typedData = JSON.parse(signParams.typedData);
+            const { domain, types, message } = typedData;
+            // ethers derives EIP712Domain itself and rejects it as an input.
+            delete types.EIP712Domain;
+            recovered = verifyTypedData(domain, types, message, signature);
+        }
+    } catch {
+        throw new Error("The signature could not be verified.");
+    }
+
+    if (!sameAddress(recovered, expectedFrom)) {
+        throw new Error(
+            "The signature was produced by a different address than the one that was approved.",
+        );
+    }
+
+    return recovered;
+}
+
+module.exports = { verifySignedTx, verifySignature, sameAddress };
--- a/src/shared/buildInfo.js
+++ b/src/shared/buildInfo.js
@@ -0,0 +1,35 @@
+// Build-time constants injected by esbuild define in build.js.
+// These globals are replaced at bundle time with string literals.
+
+/* global __BUILD_VERSION__, __BUILD_LICENSE__, __BUILD_AUTHOR__,
+          __BUILD_COMMIT__, __BUILD_COMMIT_FULL__, __BUILD_DATE__ */
+
+const BUILD_VERSION =
+    typeof __BUILD_VERSION__ !== "undefined" ? __BUILD_VERSION__ : "dev";
+const BUILD_LICENSE =
+    typeof __BUILD_LICENSE__ !== "undefined" ? __BUILD_LICENSE__ : "GPL-3.0";
+const BUILD_AUTHOR =
+    typeof __BUILD_AUTHOR__ !== "undefined"
+        ? __BUILD_AUTHOR__
+        : "sneak <sneak@sneak.berlin>";
+const BUILD_COMMIT =
+    typeof __BUILD_COMMIT__ !== "undefined" ? __BUILD_COMMIT__ : "unknown";
+const BUILD_COMMIT_FULL =
+    typeof __BUILD_COMMIT_FULL__ !== "undefined"
+        ? __BUILD_COMMIT_FULL__
+        : "unknown";
+const BUILD_DATE =
+    typeof __BUILD_DATE__ !== "undefined" ? __BUILD_DATE__ : "unknown";
+
+const GITEA_COMMIT_URL =
+    "https://git.eeqj.de/sneak/AutistMask/commit/" + BUILD_COMMIT_FULL;
+
+module.exports = {
+    BUILD_VERSION,
+    BUILD_LICENSE,
+    BUILD_AUTHOR,
+    BUILD_COMMIT,
+    BUILD_COMMIT_FULL,
+    BUILD_DATE,
+    GITEA_COMMIT_URL,
+};
--- a/src/shared/log.js
+++ b/src/shared/log.js
@@ -1,12 +1,27 @@
 // Leveled logger. Outputs to console with [AutistMask] prefix.
-// Level is DEBUG when the DEBUG constant is true, INFO otherwise.
+// Level is DEBUG when the compile-time DEBUG constant is true or the runtime
+// debugMode state flag is enabled.  The runtime flag is checked lazily so it
+// responds immediately when toggled in settings.

 const { DEBUG } = require("./constants");

 const LEVELS = { debug: 0, info: 1, warn: 2, error: 3 };
-const threshold = DEBUG ? LEVELS.debug : LEVELS.info;
+
+// Runtime debug mode flag — set by settings.js when the user toggles debug
+// mode via the easter egg.  Kept here as a simple mutable reference so it can
+// be updated without circular dependency issues with state.js.
+let _runtimeDebug = false;
+
+function setRuntimeDebug(enabled) {
+    _runtimeDebug = enabled;
+}
+
+function isDebug() {
+    return DEBUG || _runtimeDebug;
+}

 function emit(level, method, args) {
+    const threshold = isDebug() ? LEVELS.debug : LEVELS.info;
    if (LEVELS[level] >= threshold) {
        console[method]("[AutistMask]", ...args);
    }
@@ -37,4 +52,4 @@ async function debugFetch(url, opts) {
    return resp;
 }

-module.exports = { log, debugFetch };
+module.exports = { log, debugFetch, setRuntimeDebug, isDebug };
--- a/src/shared/state.js
+++ b/src/shared/state.js
@@ -29,6 +29,7 @@ const DEFAULT_STATE = {
    fraudContracts: [],
    tokenHolderCache: {},
    theme: "system",
+    debugMode: false,
 };

 const state = {
@@ -68,6 +69,7 @@ async function saveState() {
        fraudContracts: state.fraudContracts,
        tokenHolderCache: state.tokenHolderCache,
        theme: state.theme,
+        debugMode: state.debugMode,
        currentView: state.currentView,
        selectedWallet: state.selectedWallet,
        selectedAddress: state.selectedAddress,
@@ -128,6 +130,8 @@ async function loadState() {
        state.fraudContracts = saved.fraudContracts || [];
        state.tokenHolderCache = saved.tokenHolderCache || {};
        state.theme = saved.theme || "system";
+        state.debugMode =
+            saved.debugMode !== undefined ? saved.debugMode : false;
        state.currentView = saved.currentView || null;
        state.selectedWallet =
            saved.selectedWallet !== undefined ? saved.selectedWallet : null;
--- a/tests/approvalVerify.test.js
+++ b/tests/approvalVerify.test.js
@@ -0,0 +1,355 @@
+const { Network, Transaction, Wallet } = require("ethers");
+const {
+    verifySignedTx,
+    verifySignature,
+    sameAddress,
+} = require("../src/shared/approvalVerify");
+const { getSignerForAddress } = require("../src/shared/wallet");
+
+// Fixed test keys — never used for anything but these tests.
+const SIGNER_KEY =
+    "0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d";
+const OTHER_KEY =
+    "0x5de4111afa1a4b94908f83103eb1f1706367c2e68ca870fc3fb9a804cdab365a";
+
+const signer = new Wallet(SIGNER_KEY);
+const other = new Wallet(OTHER_KEY);
+
+const RECIPIENT = "0x66133E8ea0f5D1d612D2502a968757D1048c214a";
+const OTHER_RECIPIENT = "0xdAC17F958D2ee523a2206206994597C13D831ec7";
+
+// Approved parameters as a dApp would supply them over eth_sendTransaction.
+const TX_PARAMS = {
+    from: signer.address,
+    to: RECIPIENT,
+    value: "0x2386f26fc10000",
+    data: "0xdeadbeef",
+    gas: "0x5208",
+};
+
+// Build a signable transaction from approved params. The popup does the same
+// thing through populateTransaction(); here the fields are fixed so the test
+// needs no provider.
+function txFor(params) {
+    return {
+        chainId: 1,
+        nonce: 7,
+        gasLimit: 100000n,
+        maxFeePerGas: 2000000000n,
+        maxPriorityFeePerGas: 1000000000n,
+        type: 2,
+        to: params.to,
+        value: params.value === undefined ? 0n : BigInt(params.value),
+        data: params.data || "0x",
+    };
+}
+
+async function signedFor(params, withWallet) {
+    return (withWallet || signer).signTransaction(txFor(params));
+}
+
+describe("sameAddress", () => {
+    test("compares checksummed and lowercase forms as equal", () => {
+        expect(sameAddress(RECIPIENT, RECIPIENT.toLowerCase())).toBe(true);
+    });
+
+    test("treats two absent addresses as equal (contract creation)", () => {
+        expect(sameAddress(null, undefined)).toBe(true);
+        expect(sameAddress("", null)).toBe(true);
+    });
+
+    test("treats one absent address as unequal", () => {
+        expect(sameAddress(RECIPIENT, null)).toBe(false);
+        expect(sameAddress(null, RECIPIENT)).toBe(false);
+    });
+
+    test("does not throw on values that are not addresses", () => {
+        expect(sameAddress("not-an-address", RECIPIENT)).toBe(false);
+    });
+});
+
+describe("verifySignedTx", () => {
+    test("accepts the approved transaction signed by the approved address", async () => {
+        const raw = await signedFor(TX_PARAMS);
+        const parsed = verifySignedTx(raw, TX_PARAMS, signer.address);
+        expect(parsed.from).toBe(signer.address);
+        expect(parsed.hash).toBe(Transaction.from(raw).hash);
+    });
+
+    test("accepts a contract creation with no recipient", async () => {
+        const params = { to: undefined, value: "0x0", data: "0x600160005500" };
+        const raw = await signedFor(params);
+        expect(() => verifySignedTx(raw, params, signer.address)).not.toThrow();
+    });
+
+    test("accepts an absent value as zero", async () => {
+        const approved = { to: RECIPIENT, data: "0x" };
+        const raw = await signedFor(approved);
+        expect(() =>
+            verifySignedTx(raw, approved, signer.address),
+        ).not.toThrow();
+    });
+
+    test("accepts call data whose case differs from the approval", async () => {
+        const approved = { to: RECIPIENT, value: "0x0", data: "0xDEADBEEF" };
+        const raw = await signedFor(approved);
+        expect(() =>
+            verifySignedTx(raw, approved, signer.address),
+        ).not.toThrow();
+    });
+
+    test("rejects a swapped recipient", async () => {
+        const raw = await signedFor({
+            ...TX_PARAMS,
+            to: OTHER_RECIPIENT,
+        });
+        expect(() => verifySignedTx(raw, TX_PARAMS, signer.address)).toThrow(
+            /approved recipient/,
+        );
+    });
+
+    test("rejects an inflated value", async () => {
+        const raw = await signedFor({
+            ...TX_PARAMS,
+            value: "0x4563918244f40000",
+        });
+        expect(() => verifySignedTx(raw, TX_PARAMS, signer.address)).toThrow(
+            /approved value/,
+        );
+    });
+
+    test("rejects substituted call data", async () => {
+        const raw = await signedFor({ ...TX_PARAMS, data: "0xc0ffee" });
+        expect(() => verifySignedTx(raw, TX_PARAMS, signer.address)).toThrow(
+            /approved call data/,
+        );
+    });
+
+    test("rejects a transaction signed by a different address", async () => {
+        const raw = await signedFor(TX_PARAMS, other);
+        expect(() => verifySignedTx(raw, TX_PARAMS, signer.address)).toThrow(
+            /different address/,
+        );
+    });
+
+    test("rejects an unsigned transaction", () => {
+        const unsigned = Transaction.from(txFor(TX_PARAMS)).unsignedSerialized;
+        expect(() =>
+            verifySignedTx(unsigned, TX_PARAMS, signer.address),
+        ).toThrow(/no valid signature/);
+    });
+
+    test("rejects a missing or malformed payload", () => {
+        expect(() =>
+            verifySignedTx(undefined, TX_PARAMS, signer.address),
+        ).toThrow(/missing or malformed/);
+        expect(() => verifySignedTx("nope", TX_PARAMS, signer.address)).toThrow(
+            /missing or malformed/,
+        );
+        expect(() =>
+            verifySignedTx("0xc0ffee", TX_PARAMS, signer.address),
+        ).toThrow(/could not be decoded/);
+    });
+
+    test("every rejection message is a full sentence", async () => {
+        const raw = await signedFor({ ...TX_PARAMS, to: OTHER_RECIPIENT });
+        try {
+            verifySignedTx(raw, TX_PARAMS, signer.address);
+            throw new Error("expected a rejection");
+        } catch (e) {
+            expect(e.message).toMatch(/^[A-Z].*\.$/);
+        }
+    });
+});
+
+const TYPED_DATA = JSON.stringify({
+    domain: {
+        name: "AutistMask Test",
+        version: "1",
+        chainId: 1,
+        verifyingContract: OTHER_RECIPIENT,
+    },
+    primaryType: "Mail",
+    types: {
+        EIP712Domain: [
+            { name: "name", type: "string" },
+            { name: "version", type: "string" },
+            { name: "chainId", type: "uint256" },
+            { name: "verifyingContract", type: "address" },
+        ],
+        Mail: [
+            { name: "from", type: "address" },
+            { name: "to", type: "address" },
+            { name: "contents", type: "string" },
+        ],
+    },
+    message: {
+        from: signer.address,
+        to: RECIPIENT,
+        contents: "hello",
+    },
+});
+
+describe("verifySignature", () => {
+    // "Hello AutistMask" as the hex string a dApp passes to personal_sign.
+    const MESSAGE = "0x48656c6c6f204175746973744d61736b";
+    const personalParams = {
+        method: "personal_sign",
+        message: MESSAGE,
+        from: signer.address,
+    };
+    const typedParams = {
+        method: "eth_signTypedData_v4",
+        typedData: TYPED_DATA,
+        from: signer.address,
+    };
+
+    async function signPersonal(withWallet) {
+        return (withWallet || signer).signMessage(
+            Buffer.from(MESSAGE.slice(2), "hex"),
+        );
+    }
+
+    async function signTyped(withWallet) {
+        const { domain, types, message } = JSON.parse(TYPED_DATA);
+        delete types.EIP712Domain;
+        return (withWallet || signer).signTypedData(domain, types, message);
+    }
+
+    test("accepts a personal_sign signature from the approved address", async () => {
+        const signature = await signPersonal();
+        expect(verifySignature(personalParams, signature, signer.address)).toBe(
+            signer.address,
+        );
+    });
+
+    test("accepts an eth_sign signature the same way", async () => {
+        const signature = await signPersonal();
+        const params = { ...personalParams, method: "eth_sign" };
+        expect(() =>
+            verifySignature(params, signature, signer.address),
+        ).not.toThrow();
+    });
+
+    test("accepts a typed data signature from the approved address", async () => {
+        const signature = await signTyped();
+        expect(verifySignature(typedParams, signature, signer.address)).toBe(
+            signer.address,
+        );
+    });
+
+    test("does not mutate the approved typed data while verifying", async () => {
+        const signature = await signTyped();
+        const before = typedParams.typedData;
+        verifySignature(typedParams, signature, signer.address);
+        expect(typedParams.typedData).toBe(before);
+        expect(
+            JSON.parse(typedParams.typedData).types.EIP712Domain,
+        ).toBeDefined();
+    });
+
+    test("rejects a personal_sign signature from a different address", async () => {
+        const signature = await signPersonal(other);
+        expect(() =>
+            verifySignature(personalParams, signature, signer.address),
+        ).toThrow(/different address/);
+    });
+
+    test("rejects a typed data signature from a different address", async () => {
+        const signature = await signTyped(other);
+        expect(() =>
+            verifySignature(typedParams, signature, signer.address),
+        ).toThrow(/different address/);
+    });
+
+    test("rejects a signature over a different message", async () => {
+        const signature = await signer.signMessage(
+            Buffer.from("00112233", "hex"),
+        );
+        expect(() =>
+            verifySignature(personalParams, signature, signer.address),
+        ).toThrow(/different address/);
+    });
+
+    test("rejects a missing or malformed signature", async () => {
+        expect(() =>
+            verifySignature(personalParams, undefined, signer.address),
+        ).toThrow(/missing or malformed/);
+        expect(() =>
+            verifySignature(personalParams, "0x1234", signer.address),
+        ).toThrow(/could not be verified/);
+    });
+});
+
+// End-to-end over the messaging boundary, without a browser: run the exact
+// sequence the approval popup runs, then hand the artifact to the exact check
+// the background runs before it broadcasts or resolves. Only what the popup
+// puts on the wire is passed along, so this also pins down that the wire
+// payload is sufficient on its own.
+describe("popup signing sequence to background verification", () => {
+    // Stand-in for the JSON-RPC provider. populateTransaction only needs the
+    // nonce, the gas estimate, the network and the fee data.
+    const fakeProvider = {
+        getNetwork: async () => Network.from(1),
+        getTransactionCount: async () => 7,
+        estimateGas: async () => 21000n,
+        getFeeData: async () => ({
+            gasPrice: 2000000000n,
+            maxFeePerGas: 2000000000n,
+            maxPriorityFeePerGas: 1000000000n,
+        }),
+    };
+
+    // A private-key wallet as it is persisted in state, so the test goes
+    // through getSignerForAddress() the way the popup does.
+    const walletData = { type: "privkey" };
+
+    async function popupSignsTx(txParams) {
+        const localSigner = getSignerForAddress(walletData, 0, SIGNER_KEY);
+        const connected = localSigner.connect(fakeProvider);
+        const populated = await connected.populateTransaction(txParams);
+        delete populated.from;
+        return connected.signTransaction(populated);
+    }
+
+    test("a populated, signed transaction is accepted and broadcastable", async () => {
+        const rawSignedTx = await popupSignsTx(TX_PARAMS);
+        const parsed = verifySignedTx(rawSignedTx, TX_PARAMS, signer.address);
+        expect(parsed.nonce).toBe(7);
+        expect(parsed.chainId).toBe(1n);
+        expect(parsed.gasLimit).toBe(21000n);
+        expect(parsed.to).toBe(RECIPIENT);
+        expect(parsed.value).toBe(BigInt(TX_PARAMS.value));
+        expect(parsed.data).toBe(TX_PARAMS.data);
+        expect(parsed.signature).not.toBeNull();
+    });
+
+    test("the wire payload carries no password and no secret", async () => {
+        const rawSignedTx = await popupSignsTx(TX_PARAMS);
+        const payload = {
+            type: "AUTISTMASK_TX_RESPONSE",
+            id: "test-approval-id",
+            approved: true,
+            rawSignedTx,
+        };
+        expect(Object.keys(payload).sort()).toEqual([
+            "approved",
+            "id",
+            "rawSignedTx",
+            "type",
+        ]);
+        const wire = JSON.stringify(payload).toLowerCase();
+        expect(wire).not.toContain("password");
+        expect(wire).not.toContain(SIGNER_KEY.slice(2).toLowerCase());
+    });
+
+    test("the background rejects a transaction the popup did not approve", async () => {
+        const rawSignedTx = await popupSignsTx({
+            ...TX_PARAMS,
+            to: OTHER_RECIPIENT,
+        });
+        expect(() =>
+            verifySignedTx(rawSignedTx, TX_PARAMS, signer.address),
+        ).toThrow(/approved recipient/);
+    });
+});