feat(v1.3.0): add ephemeral session-key encryption for sensitive state

AGENTS.md

@@ -0,0 +1,53 @@
+# SeedPGP Agent Brief (read first)
+
+## What this repo is
+
+SeedPGP: a client-side BIP39 mnemonic encryption web app.
+Goal: add features without changing security assumptions or breaking GH Pages deploy.
+
+## Non-negotiables
+
+- Small diffs only: one feature slice per PR (1-5 files if possible).
+- No big code dumps; propose plan first, then implement.
+- Never persist secrets (mnemonic, passphrases, private keys) to localStorage/sessionStorage.
+- Prefer “explain what you found in the repo” over guessing.
+
+## How to run
+
+- Install deps: `bun install`
+- Dev: `bun run dev`
+- Build: `bun run build`
+- Tests/lint (if present): `bun run test`, `bun run lint`, `bun run typecheck`
+
+## Repo map (confirm/update)
+
+- UI entry: `src/main.tsx`
+- Components: `src/components/`
+- Core logic/types: `src/lib/`
+
+## Deploy
+
+There is a deploy script (see `scripts/deploy.sh`) and a separate public repo for built output.
+
+## Required workflow for every task
+
+1) Repo study: identify entry points + relevant modules, list files to touch.
+2) Plan: smallest vertical slice, with acceptance criteria.
+3) Implement: code + minimal tests or manual verification steps.
+4) Evidence: paste command output (build/test) and note any tradeoffs.
+
+## Security Architecture (v1.3.0+)
+
+- **Session-key encryption**: Ephemeral AES-GCM-256 key (non-exportable) encrypts sensitive state
+- **Auto-clear**: Plaintext mnemonic cleared from UI immediately after QR generation
+- **Encrypted cache**: Only ciphertext stored in React state; key lives in memory only
+- **Lock/Clear**: Manual cleanup destroys session key + clears all state
+- **Lifecycle**: Session key auto-destroyed on page close/refresh
+
+## Module: src/lib/sessionCrypto.ts
+
+- `getSessionKey()` - Generates/returns non-exportable AES-GCM key (idempotent)
+- `encryptJsonToBlob(obj)` - Encrypts to {v, alg, iv_b64, ct_b64}
+- `decryptBlobToJson(blob)` - Decrypts back to original object
+- `destroySessionKey()` - Drops key reference for GC
+- Test: `await window.runSessionCryptoTest()` (DEV only)

src/App.tsx

@@ -1,16 +1,16 @@
-import { useState } from 'react';
+import { useState, useEffect } from 'react';
 import {
   Shield,
   QrCode,
   RefreshCw,
-  CheckCircle2,
+  CheckCircle2, Lock,
   AlertCircle,
-  Lock,
   Unlock,
   Eye,
   EyeOff,
   FileKey,
-  Info
+  Info,
+  WifiOff
 } from 'lucide-react';
 import { PgpKeyInput } from './components/PgpKeyInput';
 import { QrDisplay } from './components/QrDisplay';
@@ -22,431 +22,523 @@ import * as openpgp from 'openpgp';
 import { StorageIndicator } from './components/StorageIndicator';
 import { SecurityWarnings } from './components/SecurityWarnings';
 import { ClipboardTracker } from './components/ClipboardTracker';
-
-console.log("OpenPGP.js version:", openpgp.config.versionString);
-
-function App() {
-  const [activeTab, setActiveTab] = useState<'backup' | 'restore'>('backup');
-  const [mnemonic, setMnemonic] = useState('');
-  const [backupMessagePassword, setBackupMessagePassword] = useState('');
-  const [restoreMessagePassword, setRestoreMessagePassword] = useState('');
-
-  const [publicKeyInput, setPublicKeyInput] = useState('');
-  const [privateKeyInput, setPrivateKeyInput] = useState('');
-  const [privateKeyPassphrase, setPrivateKeyPassphrase] = useState('');
-  const [hasBip39Passphrase, setHasBip39Passphrase] = useState(false);
-  const [qrPayload, setQrPayload] = useState('');
-  const [recipientFpr, setRecipientFpr] = useState('');
-  const [restoreInput, setRestoreInput] = useState('');
-  const [restoredData, setRestoredData] = useState<SeedPgpPlaintext | null>(null);
-  const [error, setError] = useState('');
-  const [loading, setLoading] = useState(false);
-  const [showMnemonic, setShowMnemonic] = useState(false);
-  const [copied, setCopied] = useState(false);
-  const [showQRScanner, setShowQRScanner] = useState(false);
-
-  const copyToClipboard = async (text: string) => {
-    try {
-      await navigator.clipboard.writeText(text);
-      setCopied(true);
-      window.setTimeout(() => setCopied(false), 1500);
-    } catch {
-      const ta = document.createElement("textarea");
-      ta.value = text;
-      ta.style.position = "fixed";
-      ta.style.left = "-9999px";
-      document.body.appendChild(ta);
-      ta.focus();
-      ta.select();
-      document.execCommand("copy");
-      document.body.removeChild(ta);
-      setCopied(true);
-      window.setTimeout(() => setCopied(false), 1500);
-    }
-  };
-
-  const handleBackup = async () => {
-    setLoading(true);
-    setError('');
-    setQrPayload('');
-    setRecipientFpr('');
-
-    try {
-      const validation = validateBip39Mnemonic(mnemonic);
-      if (!validation.valid) {
-        throw new Error(validation.error);
-      }
-
-      const plaintext = buildPlaintext(mnemonic, hasBip39Passphrase);
-
-      const result = await encryptToSeedPgp({
-        plaintext,
-        publicKeyArmored: publicKeyInput || undefined,
-        messagePassword: backupMessagePassword || undefined,  // Changed
-      });
-
-      setQrPayload(result.framed);
-      if (result.recipientFingerprint) {
-        setRecipientFpr(result.recipientFingerprint);
-      }
-    } catch (e) {
-      setError(e instanceof Error ? e.message : 'Encryption failed');
-    } finally {
-      setLoading(false);
-    }
-  };
-
-  const handleRestore = async () => {
-    setLoading(true);
-    setError('');
-    setRestoredData(null);
-
-    try {
-      const result = await decryptSeedPgp({
-        frameText: restoreInput,
-        privateKeyArmored: privateKeyInput || undefined,
-        privateKeyPassphrase: privateKeyPassphrase || undefined,
-        messagePassword: restoreMessagePassword || undefined,  // Changed
-      });
-
-
-      setRestoredData(result);
-    } catch (e) {
-      setError(e instanceof Error ? e.message : 'Decryption failed');
-    } finally {
-      setLoading(false);
-    }
-  };
-
-
-  return (
-    <>
-      <div className="min-h-screen bg-gradient-to-br from-slate-50 to-slate-100 text-slate-900 p-4 md:p-8">
-        <div className="max-w-5xl mx-auto bg-white rounded-2xl shadow-2xl overflow-hidden border border-slate-200">
-
-          {/* Header */}
-          <div className="bg-gradient-to-r from-slate-900 to-slate-800 p-6 text-white flex items-center justify-between">
-            <div className="flex items-center gap-3">
-              <div className="p-2 bg-blue-600 rounded-lg shadow-lg">
-                <Shield size={28} />
-              </div>
-              <div>
-                <h1 className="text-2xl font-bold tracking-tight">
-                  SeedPGP <span className="text-blue-400 font-mono text-base ml-2">v1.2</span>
-                </h1>
-                <p className="text-xs text-slate-400 mt-0.5">OpenPGP-secured BIP39 backup</p>
-              </div>
-            </div>
-            <div className="flex bg-slate-800/50 rounded-lg p-1 backdrop-blur">
-              <button
-                onClick={() => {
-                  setActiveTab('backup');
-                  setError('');
-                  setQrPayload('');
-                  setRestoredData(null);
-                }}
-                className={`px-5 py-2 rounded-md text-sm font-semibold transition-all ${activeTab === 'backup'
-                  ? 'bg-white text-slate-900 shadow-lg'
-                  : 'text-slate-300 hover:text-white hover:bg-slate-700/50'
-                  }`}
-              >
-                Backup
-              </button>
-              <button
-                onClick={() => {
-                  setActiveTab('restore');
-                  setError('');
-                  setQrPayload('');
-                  setRestoredData(null);
-                }}
-                className={`px-5 py-2 rounded-md text-sm font-semibold transition-all ${activeTab === 'restore'
-                  ? 'bg-white text-slate-900 shadow-lg'
-                  : 'text-slate-300 hover:text-white hover:bg-slate-700/50'
-                  }`}
-              >
-                Restore
-              </button>
-            </div>
-          </div>
-
-          <div className="p-6 md:p-8 space-y-6">
-            {/* Error Display */}
-            {error && (
-              <div className="p-4 bg-red-50 border-l-4 border-red-500 rounded-r-xl flex gap-3 text-red-800 text-sm items-start animate-in slide-in-from-top-2">
-                <AlertCircle className="shrink-0 mt-0.5" size={20} />
-                <div>
-                  <p className="font-bold mb-1">Error</p>
-                  <p className="whitespace-pre-wrap">{error}</p>
-                </div>
-              </div>
-            )}
-
-            {/* Info Banner */}
-            {recipientFpr && activeTab === 'backup' && (
-              <div className="p-3 bg-blue-50 border border-blue-200 rounded-lg flex items-start gap-3 text-blue-800 text-xs animate-in fade-in">
-                <Info size={16} className="shrink-0 mt-0.5" />
-                <div>
-                  <strong>Recipient Key:</strong> <code className="bg-blue-100 px-1.5 py-0.5 rounded font-mono">{recipientFpr}</code>
-                </div>
-              </div>
-            )}
-
-            {/* Main Content Grid */}
-            <div className="grid gap-6 md:grid-cols-3">
-              <div className="md:col-span-2 space-y-6">
-                {activeTab === 'backup' ? (
-                  <>
-                    <div className="space-y-2">
-                      <label className="text-sm font-semibold text-slate-700">BIP39 Mnemonic</label>
-                      <textarea
-                        className="w-full h-32 p-4 bg-slate-50 border border-slate-200 rounded-xl text-sm font-mono focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all resize-none"
-                        data-sensitive="BIP39 Mnemonic"
-                        placeholder="Enter your 12 or 24 word seed phrase..."
-                        value={mnemonic}
-                        onChange={(e) => setMnemonic(e.target.value)}
-                      />
-                    </div>
-
-                    <PgpKeyInput
-                      label="PGP Public Key (Optional)"
-                      icon={FileKey}
-                      placeholder="-----BEGIN PGP PUBLIC KEY BLOCK-----&#10;&#10;Paste or drag & drop your public key..."
-                      value={publicKeyInput}
-                      onChange={setPublicKeyInput}
-                    />
-                  </>
-                ) : (
-                  <>
-                    <div className="flex gap-2">
-                      <button
-                        onClick={() => setShowQRScanner(true)}
-                        className="flex-1 py-3 bg-gradient-to-r from-purple-600 to-purple-700 text-white rounded-xl font-semibold flex items-center justify-center gap-2 hover:from-purple-700 hover:to-purple-800 transition-all shadow-lg"
-                      >
-                        <QrCode size={18} />
-                        Scan QR Code
-                      </button>
-                    </div>
-
-                    <div className="space-y-2">
-                      <label className="text-sm font-semibold text-slate-700">SEEDPGP1 Payload</label>
-                      <textarea
-                        className="w-full h-32 p-4 bg-slate-50 border border-slate-200 rounded-xl text-xs font-mono focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all resize-none"
-                        placeholder="SEEDPGP1:0:ABCD:..."
-                        value={restoreInput}
-                        onChange={(e) => setRestoreInput(e.target.value)}
-                      />
-                    </div>
-
-                    <PgpKeyInput
-                      label="PGP Private Key (Optional)"
-                      icon={FileKey}
-                      data-sensitive="PGP Private Key"
-                      placeholder="-----BEGIN PGP PRIVATE KEY BLOCK-----&#10;&#10;Paste or drag & drop your private key..."
-                      value={privateKeyInput}
-                      onChange={setPrivateKeyInput}
-                    />
-
-                    {privateKeyInput && (
-                      <div className="space-y-2">
-                        <label className="text-xs font-bold text-slate-500 uppercase tracking-wider">Private Key Passphrase</label>
-                        <div className="relative">
-                          <Lock className="absolute left-3 top-3 text-slate-400" size={16} />
-                          <input
-                            type="password"
-                            data-sensitive="Message Password"
-                            className="w-full pl-10 pr-4 py-2.5 bg-white border border-slate-200 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all"
-                            placeholder="Unlock private key..."
-                            value={privateKeyPassphrase}
-                            onChange={(e) => setPrivateKeyPassphrase(e.target.value)}
-                          />
-                        </div>
-                      </div>
-                    )}
-                  </>
-                )}
-              </div>
-
-              {/* Security Panel */}
-              <div className="space-y-6">
-                <div className="p-5 bg-gradient-to-br from-slate-50 to-slate-100 rounded-2xl border-2 border-slate-200 shadow-inner space-y-4">
-                  <h3 className="text-sm font-bold text-slate-800 uppercase tracking-wider flex items-center gap-2">
-                    <Lock size={14} /> Security Options
-                  </h3>
-
-                  <div className="space-y-2">
-                    <label className="text-xs font-bold text-slate-500 uppercase tracking-wider">Message Password</label>
-                    <div className="relative">
-                      <Lock className="absolute left-3 top-3 text-slate-400" size={16} />
-                      <input
-                        type="password"
-                        className="w-full pl-10 pr-4 py-2.5 bg-white border border-slate-200 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all"
-                        placeholder="Optional password..."
-                        value={activeTab === 'backup' ? backupMessagePassword : restoreMessagePassword}
-                        onChange={(e) => activeTab === 'backup' ? setBackupMessagePassword(e.target.value) : setRestoreMessagePassword(e.target.value)}
-                      />
-                    </div>
-                    <p className="text-[10px] text-slate-500 mt-1">Symmetric encryption password (SKESK)</p>
-                  </div>
-
-
-                  {activeTab === 'backup' && (
-                    <div className="pt-3 border-t border-slate-300">
-                      <label className="flex items-center gap-2 cursor-pointer group">
-                        <input
-                          type="checkbox"
-                          checked={hasBip39Passphrase}
-                          onChange={(e) => setHasBip39Passphrase(e.target.checked)}
-                          className="rounded text-blue-600 focus:ring-2 focus:ring-blue-500 transition-all"
-                        />
-                        <span className="text-xs font-medium text-slate-700 group-hover:text-slate-900 transition-colors">
-                          BIP39 25th word active
-                        </span>
-                      </label>
-                    </div>
-                  )}
-                </div>
-
-                {/* Action Button */}
-                {activeTab === 'backup' ? (
-                  <button
-                    onClick={handleBackup}
-                    disabled={!mnemonic || loading}
-                    className="w-full py-4 bg-gradient-to-r from-blue-600 to-blue-700 text-white rounded-xl font-bold flex items-center justify-center gap-2 hover:from-blue-700 hover:to-blue-800 transition-all shadow-lg hover:shadow-xl disabled:opacity-50 disabled:cursor-not-allowed disabled:hover:from-blue-600 disabled:hover:to-blue-700"
-                  >
-                    {loading ? (
-                      <RefreshCw className="animate-spin" size={20} />
-                    ) : (
-                      <QrCode size={20} />
-                    )}
-                    {loading ? 'Generating...' : 'Generate QR Backup'}
-                  </button>
-                ) : (
-                  <button
-                    onClick={handleRestore}
-                    disabled={!restoreInput || loading}
-                    className="w-full py-4 bg-gradient-to-r from-slate-800 to-slate-900 text-white rounded-xl font-bold flex items-center justify-center gap-2 hover:from-slate-900 hover:to-black transition-all shadow-lg hover:shadow-xl disabled:opacity-50 disabled:cursor-not-allowed"
-                  >
-                    {loading ? (
-                      <RefreshCw className="animate-spin" size={20} />
-                    ) : (
-                      <Unlock size={20} />
-                    )}
-                    {loading ? 'Decrypting...' : 'Decrypt & Restore'}
-                  </button>
-                )}
-              </div>
-            </div>
-
-            {/* QR Output */}
-            {qrPayload && activeTab === 'backup' && (
-              <div className="pt-6 border-t border-slate-200 space-y-6 animate-in fade-in slide-in-from-bottom-4">
-                <div className="flex justify-center">
-                  <QrDisplay value={qrPayload} />
-                </div>
-                <div className="space-y-2">
-                  <div className="flex items-center justify-between gap-3">
-                    <label className="text-xs font-bold text-slate-500 uppercase tracking-wider">
-                      Raw payload (copy for backup)
-                    </label>
-
-                    <button
-                      type="button"
-                      onClick={() => copyToClipboard(qrPayload)}
-                      className="inline-flex items-center gap-2 px-3 py-1.5 rounded-lg bg-slate-900 text-white text-xs font-semibold hover:bg-black transition-colors"
-                    >
-                      {copied ? <CheckCircle2 size={14} /> : <QrCode size={14} />}
-                      {copied ? "Copied" : "Copy"}
-                    </button>
-                  </div>
-
-                  <textarea
-                    readOnly
-                    value={qrPayload}
-                    onFocus={(e) => e.currentTarget.select()}
-                    className="w-full h-28 p-3 bg-slate-900 rounded-xl font-mono text-[10px] text-green-400 border border-slate-700 shadow-inner leading-relaxed resize-none focus:outline-none focus:ring-2 focus:ring-blue-500"
-                  />
-                  <p className="text-[11px] text-slate-500">
-                    Tip: click the box to select all, or use Copy.
-                  </p>
-                </div>
-              </div>
-            )}
-
-            {/* Restored Mnemonic */}
-            {restoredData && activeTab === 'restore' && (
-              <div className="pt-6 border-t border-slate-200 animate-in zoom-in-95">
-                <div className="p-6 bg-gradient-to-br from-green-50 to-emerald-50 border-2 border-green-300 rounded-2xl shadow-lg">
-                  <div className="flex items-center justify-between mb-4">
-                    <span className="font-bold text-green-700 flex items-center gap-2 text-lg">
-                      <CheckCircle2 size={22} /> Mnemonic Recovered
-                    </span>
-                    <button
-                      onClick={() => setShowMnemonic(!showMnemonic)}
-                      className="p-2.5 hover:bg-green-100 rounded-xl transition-all text-green-700 hover:shadow"
-                    >
-                      {showMnemonic ? <EyeOff size={22} /> : <Eye size={22} />}
-                    </button>
-                  </div>
-
-                  <div className={`p-6 bg-white rounded-xl border-2 border-green-200 shadow-sm transition-all duration-300 ${showMnemonic ? 'blur-0' : 'blur-lg select-none'
-                    }`}>
-                    <p className="font-mono text-center text-lg text-slate-800 tracking-wide leading-relaxed break-words">
-                      {restoredData.w}
-                    </p>
-                  </div>
-
-                  {restoredData.pp === 1 && (
-                    <div className="mt-4 p-3 bg-orange-100 border border-orange-300 rounded-lg">
-                      <p className="text-xs text-center text-orange-800 font-bold uppercase tracking-widest flex items-center justify-center gap-2">
-                        <AlertCircle size={14} /> BIP39 Passphrase Required (25th Word)
-                      </p>
-                    </div>
-                  )}
-
-                  {restoredData.fpr && restoredData.fpr.length > 0 && (
-                    <div className="mt-4 p-3 bg-blue-50 border border-blue-200 rounded-lg">
-                      <p className="text-xs text-blue-800">
-                        <strong>Encrypted for keys:</strong> {restoredData.fpr.join(', ')}
-                      </p>
-                    </div>
-                  )}
-                </div>
-              </div>
-            )}
-          </div>
-        </div>
-
-        {/* Footer */}
-        <div className="mt-8 text-center text-xs text-slate-500">
-          <p>SeedPGP v1.2 • OpenPGP (RFC 4880) + Base45 (RFC 9285) + CRC16/CCITT-FALSE</p>
-          <p className="mt-1">Never share your private keys or seed phrases. Always verify on an airgapped device.</p>
-        </div>
-      </div>
-
-      {/* QR Scanner Modal */}
-      {showQRScanner && (
-        <QRScanner
-          onScanSuccess={(scannedText) => {
-            setRestoreInput(scannedText);
-            setShowQRScanner(false);
-            setError('');
-          }}
-          onClose={() => setShowQRScanner(false)}
-        />
-      )}
-      <div className="max-w-4xl mx-auto p-8">
-        <h1>SeedPGP v1.2.0</h1>
-        {/* ... rest of your app ... */}
-      </div>
-
-      {/* Floating Storage Monitor - bottom right */}
-      <StorageIndicator />
-      <SecurityWarnings />       {/* Bottom-left */}
-      <ClipboardTracker />       {/* Top-right */}
-    </>
-
-  );
-
-}
-
-export default App;
+import { ReadOnly } from './components/ReadOnly';
+import { getSessionKey, encryptJsonToBlob, decryptBlobToJson, destroySessionKey, EncryptedBlob } from './lib/sessionCrypto';
+ 
+ console.log("OpenPGP.js version:", openpgp.config.versionString);
+ 
+ function App() {
+   const [activeTab, setActiveTab] = useState<'backup' | 'restore'>('backup');
+   const [mnemonic, setMnemonic] = useState('');
+   const [backupMessagePassword, setBackupMessagePassword] = useState('');
+   const [restoreMessagePassword, setRestoreMessagePassword] = useState('');
+ 
+   const [publicKeyInput, setPublicKeyInput] = useState('');
+   const [privateKeyInput, setPrivateKeyInput] = useState('');
+   const [privateKeyPassphrase, setPrivateKeyPassphrase] = useState('');
+   const [hasBip39Passphrase, setHasBip39Passphrase] = useState(false);
+   const [qrPayload, setQrPayload] = useState('');
+   const [recipientFpr, setRecipientFpr] = useState('');
+   const [restoreInput, setRestoreInput] = useState('');
+   const [restoredData, setRestoredData] = useState<SeedPgpPlaintext | null>(null);
+   const [error, setError] = useState('');
+   const [loading, setLoading] = useState(false);
+   const [showMnemonic, setShowMnemonic] = useState(false);
+   const [copied, setCopied] = useState(false);
+   const [showQRScanner, setShowQRScanner] = useState(false);
+   const [isReadOnly, setIsReadOnly] = useState(false);
+   const [encryptedMnemonicCache, setEncryptedMnemonicCache] = useState<EncryptedBlob | null>(null);
+ 
+   useEffect(() => {
+     // When entering read-only mode, clear sensitive data for security.
+     if (isReadOnly) {
+       setMnemonic('');
+       setBackupMessagePassword('');
+       setRestoreMessagePassword('');
+       setPublicKeyInput('');
+       setPrivateKeyInput('');
+       setPrivateKeyPassphrase('');
+       setQrPayload('');
+       setRestoreInput('');
+       setRestoredData(null);
+       setError('');
+     }
+   }, [isReadOnly]);
+ 
+   // Cleanup session key on component unmount
+   useEffect(() => {
+     return () => {
+       destroySessionKey();
+     };
+   }, []);
+ 
+ 
+   const copyToClipboard = async (text: string) => {
+     if (isReadOnly) {
+       setError("Copy to clipboard is disabled in Read-only mode.");
+       return;
+     }
+     try {
+       await navigator.clipboard.writeText(text);
+       setCopied(true);
+       window.setTimeout(() => setCopied(false), 1500);
+     } catch {
+       const ta = document.createElement("textarea");
+       ta.value = text;
+       ta.style.position = "fixed";
+       ta.style.left = "-9999px";
+       document.body.appendChild(ta);
+       ta.focus();
+       ta.select();
+       document.execCommand("copy");
+       document.body.removeChild(ta);
+       setCopied(true);
+       window.setTimeout(() => setCopied(false), 1500);
+     }
+   };
+ 
+   const handleBackup = async () => {
+     setLoading(true);
+     setError('');
+     setQrPayload('');
+     setRecipientFpr('');
+ 
+     try {
+       const validation = validateBip39Mnemonic(mnemonic);
+       if (!validation.valid) {
+         throw new Error(validation.error);
+       }
+ 
+       const plaintext = buildPlaintext(mnemonic, hasBip39Passphrase);
+ 
+       const result = await encryptToSeedPgp({
+         plaintext,
+         publicKeyArmored: publicKeyInput || undefined,
+         messagePassword: backupMessagePassword || undefined,
+       });
+ 
+       setQrPayload(result.framed);
+       if (result.recipientFingerprint) {
+         setRecipientFpr(result.recipientFingerprint);
+       }
+ 
+       // Encrypt mnemonic with session key and clear plaintext state
+       const blob = await encryptJsonToBlob({ mnemonic, timestamp: Date.now() });
+       setEncryptedMnemonicCache(blob);
+       setMnemonic(''); // Clear plaintext mnemonic
+     } catch (e) {
+       setError(e instanceof Error ? e.message : 'Encryption failed');
+     } finally {
+       setLoading(false);
+     }
+   };
+ 
+   const handleRestore = async () => {
+     setLoading(true);
+     setError('');
+     setRestoredData(null);
+ 
+     try {
+       const result = await decryptSeedPgp({
+         frameText: restoreInput,
+         privateKeyArmored: privateKeyInput || undefined,
+         privateKeyPassphrase: privateKeyPassphrase || undefined,
+         messagePassword: restoreMessagePassword || undefined,
+       });
+ 
+ 
+       setRestoredData(result);
+     } catch (e) {
+       setError(e instanceof Error ? e.message : 'Decryption failed');
+     } finally {
+       setLoading(false);
+     }
+   };
+ 
+   const handleLockAndClear = () => {
+     destroySessionKey();
+     setEncryptedMnemonicCache(null);
+     setMnemonic('');
+     setBackupMessagePassword('');
+     setRestoreMessagePassword('');
+     setPublicKeyInput('');
+     setPrivateKeyInput('');
+     setPrivateKeyPassphrase('');
+     setQrPayload('');
+     setRecipientFpr('');
+     setRestoreInput('');
+     setRestoredData(null);
+     setError('');
+     setShowMnemonic(false);
+     setCopied(false);
+     setShowQRScanner(false);
+   };
+ 
+ 
+   return (
+     <>
+       <div className="min-h-screen bg-gradient-to-br from-slate-50 to-slate-100 text-slate-900 p-4 md:p-8">
+         <div className="max-w-5xl mx-auto bg-white rounded-2xl shadow-2xl overflow-hidden border border-slate-200">
+ 
+           {/* Header */}
+           <div className="bg-gradient-to-r from-slate-900 to-slate-800 p-6 text-white flex items-center justify-between">
+             <div className="flex items-center gap-3">
+               <div className="p-2 bg-blue-600 rounded-lg shadow-lg">
+                 <Shield size={28} />
+               </div>
+               <div>
+                 <h1 className="text-2xl font-bold tracking-tight">
+                   SeedPGP <span className="text-blue-400 font-mono text-base ml-2">v{__APP_VERSION__}</span>
+                 </h1>
+                 <p className="text-xs text-slate-400 mt-0.5">OpenPGP-secured BIP39 backup</p>
+               </div>
+             </div>
+             {encryptedMnemonicCache && ( // Show only if encrypted data exists
+               <button
+                 onClick={handleLockAndClear}
+                 className="flex items-center gap-2 text-sm text-red-400 bg-slate-800/50 px-3 py-1.5 rounded-lg hover:bg-red-900/50 transition-colors"
+               >
+                 <Lock size={16} />
+                 <span>Lock/Clear</span>
+               </button>
+             )}
+             <div className="flex items-center gap-4">
+               {isReadOnly && (
+                 <div className="flex items-center gap-2 text-sm text-amber-400 bg-slate-800/50 px-3 py-1.5 rounded-lg">
+                   <WifiOff size={16} />
+                   <span>Read-only</span>
+                 </div>
+               )}
+               <div className="flex bg-slate-800/50 rounded-lg p-1 backdrop-blur">
+                 <button
+                   onClick={() => {
+                     setActiveTab('backup');
+                     setError('');
+                     setQrPayload('');
+                     setRestoredData(null);
+                   }}
+                   className={`px-5 py-2 rounded-md text-sm font-semibold transition-all ${activeTab === 'backup'
+                     ? 'bg-white text-slate-900 shadow-lg'
+                     : 'text-slate-300 hover:text-white hover:bg-slate-700/50'
+                     }`}
+                 >
+                   Backup
+                 </button>
+                 <button
+                   onClick={() => {
+                     setActiveTab('restore');
+                     setError('');
+                     setQrPayload('');
+                     setRestoredData(null);
+                   }}
+                   className={`px-5 py-2 rounded-md text-sm font-semibold transition-all ${activeTab === 'restore'
+                     ? 'bg-white text-slate-900 shadow-lg'
+                     : 'text-slate-300 hover:text-white hover:bg-slate-700/50'
+                     }`}
+                 >
+                   Restore
+                 </button>
+               </div>
+             </div>
+           </div>
+ 
+           <div className="p-6 md:p-8 space-y-6">
+             {/* Error Display */}
+             {error && (
+               <div className="p-4 bg-red-50 border-l-4 border-red-500 rounded-r-xl flex gap-3 text-red-800 text-sm items-start animate-in slide-in-from-top-2">
+                 <AlertCircle className="shrink-0 mt-0.5" size={20} />
+                 <div>
+                   <p className="font-bold mb-1">Error</p>
+                   <p className="whitespace-pre-wrap">{error}</p>
+                 </div>
+               </div>
+             )}
+ 
+             {/* Info Banner */}
+             {recipientFpr && activeTab === 'backup' && (
+               <div className="p-3 bg-blue-50 border border-blue-200 rounded-lg flex items-start gap-3 text-blue-800 text-xs animate-in fade-in">
+                 <Info size={16} className="shrink-0 mt-0.5" />
+                 <div>
+                   <strong>Recipient Key:</strong> <code className="bg-blue-100 px-1.5 py-0.5 rounded font-mono">{recipientFpr}</code>
+                 </div>
+               </div>
+             )}
+ 
+             {/* Main Content Grid */}
+             <div className="grid gap-6 md:grid-cols-3">
+               <div className="md:col-span-2 space-y-6">
+                 {activeTab === 'backup' ? (
+                   <>
+                     <div className="space-y-2">
+                       <label className="text-sm font-semibold text-slate-700">BIP39 Mnemonic</label>
+                       <textarea
+                         className="w-full h-32 p-4 bg-slate-50 border border-slate-200 rounded-xl text-sm font-mono focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all resize-none"
+                         data-sensitive="BIP39 Mnemonic"
+                         placeholder="Enter your 12 or 24 word seed phrase..."
+                         value={mnemonic}
+                         onChange={(e) => setMnemonic(e.target.value)}
+                         readOnly={isReadOnly}
+                       />
+                     </div>
+ 
+                     <PgpKeyInput
+                       label="PGP Public Key (Optional)"
+                       icon={FileKey}
+                       placeholder="-----BEGIN PGP PUBLIC KEY BLOCK-----&#10;&#10;Paste or drag & drop your public key..."
+                       value={publicKeyInput}
+                       onChange={setPublicKeyInput}
+                       readOnly={isReadOnly}
+                     />
+                   </>
+                 ) : (
+                   <>
+                     <div className="flex gap-2">
+                       <button
+                         onClick={() => setShowQRScanner(true)}
+                         disabled={isReadOnly}
+                         className="flex-1 py-3 bg-gradient-to-r from-purple-600 to-purple-700 text-white rounded-xl font-semibold flex items-center justify-center gap-2 hover:from-purple-700 hover:to-purple-800 transition-all shadow-lg disabled:opacity-50"
+                       >
+                         <QrCode size={18} />
+                         Scan QR Code
+                       </button>
+                     </div>
+ 
+                     <div className="space-y-2">
+                       <label className="text-sm font-semibold text-slate-700">SEEDPGP1 Payload</label>
+                       <textarea
+                         className="w-full h-32 p-4 bg-slate-50 border border-slate-200 rounded-xl text-xs font-mono focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all resize-none"
+                         placeholder="SEEDPGP1:0:ABCD:..."
+                         value={restoreInput}
+                         onChange={(e) => setRestoreInput(e.target.value)}
+                         readOnly={isReadOnly}
+                       />
+                     </div>
+ 
+                     <PgpKeyInput
+                       label="PGP Private Key (Optional)"
+                       icon={FileKey}
+                       data-sensitive="PGP Private Key"
+                       placeholder="-----BEGIN PGP PRIVATE KEY BLOCK-----&#10;&#10;Paste or drag & drop your private key..."
+                       value={privateKeyInput}
+                       onChange={setPrivateKeyInput}
+                       readOnly={isReadOnly}
+                     />
+ 
+                     {privateKeyInput && (
+                       <div className="space-y-2">
+                         <label className="text-xs font-bold text-slate-500 uppercase tracking-wider">Private Key Passphrase</label>
+                         <div className="relative">
+                           <Lock className="absolute left-3 top-3 text-slate-400" size={16} />
+                           <input
+                             type="password"
+                             data-sensitive="Message Password"
+                             className="w-full pl-10 pr-4 py-2.5 bg-white border border-slate-200 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all"
+                             placeholder="Unlock private key..."
+                             value={privateKeyPassphrase}
+                             onChange={(e) => setPrivateKeyPassphrase(e.target.value)}
+                             readOnly={isReadOnly}
+                           />
+                         </div>
+                       </div>
+                     )}
+                   </>
+                 )}
+               </div>
+ 
+               {/* Security Panel */}
+               <div className="space-y-6">
+                 <div className="p-5 bg-gradient-to-br from-slate-50 to-slate-100 rounded-2xl border-2 border-slate-200 shadow-inner space-y-4">
+                   <h3 className="text-sm font-bold text-slate-800 uppercase tracking-wider flex items-center gap-2">
+                     <Lock size={14} /> Security Options
+                   </h3>
+ 
+                   <div className="space-y-2">
+                     <label className="text-xs font-bold text-slate-500 uppercase tracking-wider">Message Password</label>
+                     <div className="relative">
+                       <Lock className="absolute left-3 top-3 text-slate-400" size={16} />
+                       <input
+                         type="password"
+                         className="w-full pl-10 pr-4 py-2.5 bg-white border border-slate-200 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all"
+                         placeholder="Optional password..."
+                         value={activeTab === 'backup' ? backupMessagePassword : restoreMessagePassword}
+                         onChange={(e) => activeTab === 'backup' ? setBackupMessagePassword(e.target.value) : setRestoreMessagePassword(e.target.value)}
+                         readOnly={isReadOnly}
+                       />
+                     </div>
+                     <p className="text-[10px] text-slate-500 mt-1">Symmetric encryption password (SKESK)</p>
+                   </div>
+ 
+ 
+                   {activeTab === 'backup' && (
+                     <div className="pt-3 border-t border-slate-300">
+                       <label className="flex items-center gap-2 cursor-pointer group">
+                         <input
+                           type="checkbox"
+                           checked={hasBip39Passphrase}
+                           onChange={(e) => setHasBip39Passphrase(e.target.checked)}
+                           disabled={isReadOnly}
+                           className="rounded text-blue-600 focus:ring-2 focus:ring-blue-500 transition-all"
+                         />
+                         <span className="text-xs font-medium text-slate-700 group-hover:text-slate-900 transition-colors">
+                           BIP39 25th word active
+                         </span>
+                       </label>
+                     </div>
+                   )}
+ 
+                   <ReadOnly
+                     isReadOnly={isReadOnly}
+                     onToggle={setIsReadOnly}
+                     appVersion={__APP_VERSION__}
+                     buildHash={__BUILD_HASH__}
+                   />
+                 </div>
+ 
+                 {/* Action Button */}
+                 {activeTab === 'backup' ? (
+                   <button
+                     onClick={handleBackup}
+                     disabled={!mnemonic || loading || isReadOnly}
+                     className="w-full py-4 bg-gradient-to-r from-blue-600 to-blue-700 text-white rounded-xl font-bold flex items-center justify-center gap-2 hover:from-blue-700 hover:to-blue-800 transition-all shadow-lg hover:shadow-xl disabled:opacity-50 disabled:cursor-not-allowed disabled:hover:from-blue-600 disabled:hover:to-blue-700"
+                   >
+                     {loading ? (
+                       <RefreshCw className="animate-spin" size={20} />
+                     ) : (
+                       <QrCode size={20} />
+                     )}
+                     {loading ? 'Generating...' : 'Generate QR Backup'}
+                   </button>
+                 ) : (
+                   <button
+                     onClick={handleRestore}
+                     disabled={!restoreInput || loading || isReadOnly}
+                     className="w-full py-4 bg-gradient-to-r from-slate-800 to-slate-900 text-white rounded-xl font-bold flex items-center justify-center gap-2 hover:from-slate-900 hover:to-black transition-all shadow-lg hover:shadow-xl disabled:opacity-50 disabled:cursor-not-allowed"
+                   >
+                     {loading ? (
+                       <RefreshCw className="animate-spin" size={20} />
+                     ) : (
+                       <Unlock size={20} />
+                     )}
+                     {loading ? 'Decrypting...' : 'Decrypt & Restore'}
+                   </button>
+                 )}
+               </div>
+             </div>
+ 
+             {/* QR Output */}
+             {qrPayload && activeTab === 'backup' && (
+               <div className="pt-6 border-t border-slate-200 space-y-6 animate-in fade-in slide-in-from-bottom-4">
+                 <div className="flex justify-center">
+                   <QrDisplay value={qrPayload} />
+                 </div>
+                 <div className="space-y-2">
+                   <div className="flex items-center justify-between gap-3">
+                     <label className="text-xs font-bold text-slate-500 uppercase tracking-wider">
+                       Raw payload (copy for backup)
+                     </label>
+ 
+                     <button
+                       type="button"
+                       onClick={() => copyToClipboard(qrPayload)}
+                       className="inline-flex items-center gap-2 px-3 py-1.5 rounded-lg bg-slate-900 text-white text-xs font-semibold hover:bg-black transition-colors"
+                     >
+                       {copied ? <CheckCircle2 size={14} /> : <QrCode size={14} />}
+                       {copied ? "Copied" : "Copy"}
+                     </button>
+                   </div>
+ 
+                   <textarea
+                     readOnly
+                     value={qrPayload}
+                     onFocus={(e) => e.currentTarget.select()}
+                     className="w-full h-28 p-3 bg-slate-900 rounded-xl font-mono text-[10px] text-green-400 border border-slate-700 shadow-inner leading-relaxed resize-none focus:outline-none focus:ring-2 focus:ring-blue-500"
+                   />
+                   <p className="text-[11px] text-slate-500">
+                     Tip: click the box to select all, or use Copy.
+                   </p>
+                 </div>
+               </div>
+             )}
+ 
+             {/* Restored Mnemonic */}
+             {restoredData && activeTab === 'restore' && (
+               <div className="pt-6 border-t border-slate-200 animate-in zoom-in-95">
+                 <div className="p-6 bg-gradient-to-br from-green-50 to-emerald-50 border-2 border-green-300 rounded-2xl shadow-lg">
+                   <div className="flex items-center justify-between mb-4">
+                     <span className="font-bold text-green-700 flex items-center gap-2 text-lg">
+                       <CheckCircle2 size={22} /> Mnemonic Recovered
+                     </span>
+                     <button
+                       onClick={() => setShowMnemonic(!showMnemonic)}
+                       className="p-2.5 hover:bg-green-100 rounded-xl transition-all text-green-700 hover:shadow"
+                     >
+                       {showMnemonic ? <EyeOff size={22} /> : <Eye size={22} />}
+                     </button>
+                   </div>
+ 
+                   <div className={`p-6 bg-white rounded-xl border-2 border-green-200 shadow-sm transition-all duration-300 ${showMnemonic ? 'blur-0' : 'blur-lg select-none'
+                     }`}>
+                     <p className="font-mono text-center text-lg text-slate-800 tracking-wide leading-relaxed break-words">
+                       {restoredData.w}
+                     </p>
+                   </div>
+ 
+                   {restoredData.pp === 1 && (
+                     <div className="mt-4 p-3 bg-orange-100 border border-orange-300 rounded-lg">
+                       <p className="text-xs text-center text-orange-800 font-bold uppercase tracking-widest flex items-center justify-center gap-2">
+                         <AlertCircle size={14} /> BIP39 Passphrase Required (25th Word)
+                       </p>
+                     </div>
+                   )}
+ 
+                   {restoredData.fpr && restoredData.fpr.length > 0 && (
+                     <div className="mt-4 p-3 bg-blue-50 border border-blue-200 rounded-lg">
+                       <p className="text-xs text-blue-800">
+                         <strong>Encrypted for keys:</strong> {restoredData.fpr.join(', ')}
+                       </p>
+                     </div>
+                   )}
+                 </div>
+               </div>
+             )}
+           </div>
+         </div>
+ 
+         {/* Footer */}
+         <div className="mt-8 text-center text-xs text-slate-500">
+           <p>SeedPGP v{__APP_VERSION__} • OpenPGP (RFC 4880) + Base45 (RFC 9285) + CRC16/CCITT-FALSE</p>
+           <p className="mt-1">Never share your private keys or seed phrases. Always verify on an airgapped device.</p>
+         </div>
+       </div>
+ 
+       {/* QR Scanner Modal */}
+       {showQRScanner && (
+         <QRScanner
+           onScanSuccess={(scannedText) => {
+             setRestoreInput(scannedText);
+             setShowQRScanner(false);
+             setError('');
+           }}
+           onClose={() => setShowQRScanner(false)}
+         />
+       )}
+       <div className="max-w-4xl mx-auto p-8">
+         <h1>SeedPGP v1.2.0</h1>
+         {/* ... rest of your app ... */}
+       </div>
+ 
+       {/* Floating Storage Monitor - bottom right */}
+       {!isReadOnly && (
+         <>
+           <StorageIndicator />
+           <SecurityWarnings />
+           <ClipboardTracker />
+         </>
+       )}
+     </>
+ 
+   );
+ 
+ }
+ 
+ export default App;

src/components/PgpKeyInput.tsx

@@ -1,15 +1,14 @@
 import React, { useState } from 'react';
 import { Upload } from 'lucide-react';
 import type { LucideIcon } from "lucide-react";
+
 interface PgpKeyInputProps {
     value: string;
     onChange: (value: string) => void;
     placeholder: string;
     label: string;
     icon?: LucideIcon;
-
-
-
+    readOnly?: boolean;
 }
 
 export const PgpKeyInput: React.FC<PgpKeyInputProps> = ({
@@ -17,21 +16,25 @@ export const PgpKeyInput: React.FC<PgpKeyInputProps> = ({
     onChange,
     placeholder,
     label,
-    icon: Icon
+    icon: Icon,
+    readOnly = false,
 }) => {
     const [isDragging, setIsDragging] = useState(false);
 
     const handleDragOver = (e: React.DragEvent) => {
+        if (readOnly) return;
         e.preventDefault();
         setIsDragging(true);
     };
 
     const handleDragLeave = (e: React.DragEvent) => {
+        if (readOnly) return;
         e.preventDefault();
         setIsDragging(false);
     };
 
     const handleDrop = (e: React.DragEvent) => {
+        if (readOnly) return;
         e.preventDefault();
         setIsDragging(false);
 
@@ -53,24 +56,27 @@ export const PgpKeyInput: React.FC<PgpKeyInputProps> = ({
                 <span className="flex items-center gap-2">
                     {Icon && <Icon size={14} />} {label}
                 </span>
-                <span className="text-[10px] text-slate-400 font-normal bg-slate-100 px-2 py-0.5 rounded-full border border-slate-200">
-                    Drag & Drop .asc file
-                </span>
+                {!readOnly && (
+                    <span className="text-[10px] text-slate-400 font-normal bg-slate-100 px-2 py-0.5 rounded-full border border-slate-200">
+                        Drag & Drop .asc file
+                    </span>
+                )}
             </label>
             <div
-                className={`relative transition-all duration-200 ${isDragging ? 'scale-[1.01]' : ''}`}
+                className={`relative transition-all duration-200 ${isDragging && !readOnly ? 'scale-[1.01]' : ''}`}
                 onDragOver={handleDragOver}
                 onDragLeave={handleDragLeave}
                 onDrop={handleDrop}
             >
                 <textarea
-                    className={`w-full h-40 p-3 bg-slate-50 border rounded-xl text-xs font-mono transition-colors resize-none focus:outline-none focus:ring-2 focus:ring-blue-500 ${isDragging ? 'border-blue-500 bg-blue-50' : 'border-slate-200'
+                    className={`w-full h-40 p-3 bg-slate-50 border rounded-xl text-xs font-mono transition-colors resize-none focus:outline-none focus:ring-2 focus:ring-blue-500 ${isDragging && !readOnly ? 'border-blue-500 bg-blue-50' : 'border-slate-200'
                         }`}
                     placeholder={placeholder}
                     value={value}
                     onChange={(e) => onChange(e.target.value)}
+                    readOnly={readOnly}
                 />
-                {isDragging && (
+                {isDragging && !readOnly && (
                     <div className="absolute inset-0 flex items-center justify-center bg-blue-50/90 rounded-xl border-2 border-dashed border-blue-500 pointer-events-none z-10">
                         <div className="text-blue-600 font-bold flex flex-col items-center animate-bounce">
                             <Upload size={24} />

src/components/ReadOnly.tsx

@@ -0,0 +1,39 @@
+import { Shield, WifiOff } from 'lucide-react';
+
+type ReadOnlyProps = {
+  isReadOnly: boolean;
+  onToggle: (isReadOnly: boolean) => void;
+  buildHash: string;
+  appVersion: string;
+};
+
+const CSP_POLICY = `default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; connect-src 'none';`;
+
+export function ReadOnly({ isReadOnly, onToggle, buildHash, appVersion }: ReadOnlyProps) {
+  return (
+    <div className="pt-3 border-t border-slate-300">
+      <label className="flex items-center gap-2 cursor-pointer group">
+        <input
+          type="checkbox"
+          checked={isReadOnly}
+          onChange={(e) => onToggle(e.target.checked)}
+          className="rounded text-blue-600 focus:ring-2 focus:ring-blue-500 transition-all"
+        />
+        <span className="text-xs font-medium text-slate-700 group-hover:text-slate-900 transition-colors">
+          Read-only Mode
+        </span>
+      </label>
+      {isReadOnly && (
+        <div className="mt-4 p-3 bg-slate-800 text-slate-200 rounded-lg text-xs space-y-2 animate-in fade-in">
+          <p className="font-bold flex items-center gap-2"><WifiOff size={14} /> Network & Persistence Disabled</p>
+          <div className="font-mono text-[10px] space-y-1">
+            <p><span className="font-semibold text-slate-400">Version:</span> {appVersion}</p>
+            <p><span className="font-semibold text-slate-400">Build:</span> {buildHash}</p>
+            <p className="pt-1 font-semibold text-slate-400">Content Security Policy:</p>
+            <p className="text-sky-300 break-words">{CSP_POLICY}</p>
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}

src/lib/sessionCrypto.ts

@@ -0,0 +1,205 @@
+/**
+ * @file Ephemeral, per-session, in-memory encryption using Web Crypto API.
+ *
+ * This module manages a single, non-exportable AES-GCM key for a user's session.
+ * It's designed to encrypt sensitive data (like a mnemonic) before it's placed
+ * into React state, mitigating the risk of plaintext data in memory snapshots.
+ * The key is destroyed when the user navigates away or the session ends.
+ */
+
+// --- Helper functions for encoding ---
+
+function base64ToBytes(base64: string): Uint8Array {
+  const binString = atob(base64);
+  return Uint8Array.from(binString, (m) => m.codePointAt(0)!);
+}
+
+function bytesToBase64(bytes: Uint8Array): string {
+  const binString = Array.from(bytes, (byte) =>
+    String.fromCodePoint(byte),
+  ).join("");
+  return btoa(binString);
+}
+
+// --- Module-level state ---
+
+/**
+ * Holds the session's AES-GCM key. This variable is not exported and is
+ * only accessible through the functions in this module.
+ * @private
+ */
+let sessionKey: CryptoKey | null = null;
+const KEY_ALGORITHM = 'AES-GCM';
+const KEY_LENGTH = 256;
+
+/**
+ * An object containing encrypted data and necessary metadata for decryption.
+ */
+export interface EncryptedBlob {
+  v: 1;
+  /**
+   * The algorithm used. This is metadata; the actual Web Crypto API call
+   * uses `{ name: "AES-GCM", length: 256 }`.
+   */
+  alg: 'A256GCM';
+  iv_b64: string; // Initialization Vector (base64)
+  ct_b64: string; // Ciphertext (base64)
+}
+
+// --- Core API Functions ---
+
+/**
+ * Generates and stores a session-level AES-GCM 256-bit key.
+ * The key is non-exportable and is held in a private module-level variable.
+ * If a key already exists, the existing key is returned, making the function idempotent.
+ * This function must be called before any encryption or decryption can occur.
+ * @returns A promise that resolves to the generated or existing CryptoKey.
+ */
+export async function getSessionKey(): Promise<CryptoKey> {
+  if (sessionKey) {
+    return sessionKey;
+  }
+
+  const key = await window.crypto.subtle.generateKey(
+    {
+      name: KEY_ALGORITHM,
+      length: KEY_LENGTH,
+    },
+    false, // non-exportable
+    ['encrypt', 'decrypt'],
+  );
+  sessionKey = key;
+  return key;
+}
+
+/**
+ * Encrypts a JSON-serializable object using the current session key.
+ * @param data The object to encrypt. Must be JSON-serializable.
+ * @returns A promise that resolves to an EncryptedBlob.
+ */
+export async function encryptJsonToBlob<T>(data: T): Promise<EncryptedBlob> {
+  if (!sessionKey) {
+    throw new Error('Session key not initialized. Call getSessionKey() first.');
+  }
+
+  const iv = window.crypto.getRandomValues(new Uint8Array(12)); // 96-bit IV is recommended for AES-GCM
+  const plaintext = new TextEncoder().encode(JSON.stringify(data));
+
+  const ciphertext = await window.crypto.subtle.encrypt(
+    {
+      name: KEY_ALGORITHM,
+      iv: iv,
+    },
+    sessionKey,
+    plaintext,
+  );
+
+  return {
+    v: 1,
+    alg: 'A256GCM',
+    iv_b64: bytesToBase64(iv),
+    ct_b64: bytesToBase64(new Uint8Array(ciphertext)),
+  };
+}
+
+/**
+ * Decrypts an EncryptedBlob back into its original object form.
+ * @param blob The EncryptedBlob to decrypt.
+ * @returns A promise that resolves to the original decrypted object.
+ */
+export async function decryptBlobToJson<T>(blob: EncryptedBlob): Promise<T> {
+  if (!sessionKey) {
+    throw new Error('Session key not initialized or has been destroyed.');
+  }
+  if (blob.v !== 1 || blob.alg !== 'A256GCM') {
+    throw new Error('Invalid or unsupported encrypted blob format.');
+  }
+
+  const iv = base64ToBytes(blob.iv_b64);
+  const ciphertext = base64ToBytes(blob.ct_b64);
+
+  const decrypted = await window.crypto.subtle.decrypt(
+    {
+      name: KEY_ALGORITHM,
+      iv: iv,
+    },
+    sessionKey,
+    ciphertext,
+  );
+
+  const jsonString = new TextDecoder().decode(decrypted);
+  return JSON.parse(jsonString) as T;
+}
+
+/**
+ * Destroys the session key reference, making it unavailable for future
+ * operations and allowing it to be garbage collected.
+ */
+export function destroySessionKey(): void {
+  sessionKey = null;
+}
+
+/**
+ * A standalone test function that can be run in the browser console
+ * to verify the complete encryption and decryption lifecycle.
+ *
+ * To use:
+ * 1. Copy this entire function into the browser's developer console.
+ * 2. Run it by typing: `await runSessionCryptoTest()`
+ * 3. Check the console for logs.
+ */
+export async function runSessionCryptoTest(): Promise<void> {
+  console.log('--- Running Session Crypto Test ---');
+  try {
+    // 1. Destroy any old key
+    destroySessionKey();
+    console.log('Old key destroyed (if any).');
+
+    // 2. Generate a new key
+    await getSessionKey();
+    console.log('New session key generated.');
+
+    // 3. Define a secret object
+    const originalObject = {
+      mnemonic: 'fee table visa input phrase lake buffalo vague merit million mesh blend',
+      timestamp: new Date().toISOString(),
+    };
+    console.log('Original object:', originalObject);
+
+    // 4. Encrypt the object
+    const encrypted = await encryptJsonToBlob(originalObject);
+    console.log('Encrypted blob:', encrypted);
+    if (typeof encrypted.ct_b64 !== 'string' || encrypted.ct_b64.length < 20) {
+      throw new Error('Encryption failed: ciphertext looks invalid.');
+    }
+
+    // 5. Decrypt the object
+    const decrypted = await decryptBlobToJson(encrypted);
+    console.log('Decrypted object:', decrypted);
+
+    // 6. Verify integrity
+    if (JSON.stringify(originalObject) !== JSON.stringify(decrypted)) {
+      throw new Error('Verification failed: Decrypted data does not match original data.');
+    }
+    console.log('%c✅ Success: Data integrity verified.', 'color: green; font-weight: bold;');
+
+    // 7. Test key destruction
+    destroySessionKey();
+    console.log('Session key destroyed.');
+    try {
+      await decryptBlobToJson(encrypted);
+    } catch (e) {
+      console.log('As expected, decryption failed after key destruction:', (e as Error).message);
+    }
+  } catch (error) {
+    console.error('%c❌ Test Failed:', 'color: red; font-weight: bold;', error);
+  } finally {
+    console.log('--- Test Complete ---');
+  }
+}
+
+// For convenience, attach the test runner to the window object.
+// This is for development/testing only and can be removed in production.
+if (import.meta.env.DEV && typeof window !== 'undefined') {
+  (window as any).runSessionCryptoTest = runSessionCryptoTest;
+}

src/main.tsx

@@ -23,6 +23,10 @@ import { createRoot } from 'react-dom/client'
 import './index.css'
 import App from './App'
 
+if (import.meta.env.DEV) {
+  await import('./lib/sessionCrypto');
+}
+
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
     <App />

src/vite-env.d.ts

@@ -6,3 +6,5 @@ declare module '*.css' {
   export default content;
 }
 
+declare const __APP_VERSION__: string;
+declare const __BUILD_HASH__: string;

vite.config.ts

@@ -1,5 +1,14 @@
 import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
+import { execSync } from 'child_process'
+import fs from 'fs'
+
+// Read version from package.json
+const packageJson = JSON.parse(fs.readFileSync('./package.json', 'utf-8'))
+const appVersion = packageJson.version
+
+// Get git commit hash
+const gitHash = execSync('git rev-parse --short HEAD').toString().trim()
 
 export default defineConfig({
   plugins: [react()],
@@ -7,5 +16,9 @@ export default defineConfig({
   build: {
     outDir: 'dist',
     emptyOutDir: false,
+  },
+  define: {
+    '__APP_VERSION__': JSON.stringify(appVersion),
+    '__BUILD_HASH__': JSON.stringify(gitHash),
   }
 })