Initial public release: Nym-native anonymous submission system

End-to-end verified pipeline (browser -> HTTP relay -> Nym mixnet -> reader).
Client-side X25519+HKDF+AES-GCM-256, no-log blind relay, AGPL-3.0.

3 files changed, 351 insertions, 0 deletions

diff --git a/static/crypto.js b/static/crypto.js
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--- /dev/null
+++ b/static/crypto.js
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+// NymDrop — client-side encryption via WebCrypto API.
+// No external libraries. Plaintext never leaves the browser.
+
+// Server's X25519 public key — replaced at deploy time.
+const NYMDROP_PUBKEY_HEX = "6aa99a672c48cb8eee65ddd5c5e5f8947a8d52d39a8b8eb4e11b15c87fe49038";
+
+async function hexToBytes(hex) {
+    const bytes = new Uint8Array(hex.length / 2);
+    for (let i = 0; i < hex.length; i += 2)
+        bytes[i / 2] = parseInt(hex.substr(i, 2), 16);
+    return bytes;
+}
+
+async function encryptPayload(plaintext) {
+    const serverPubBytes = await hexToBytes(NYMDROP_PUBKEY_HEX);
+
+    // Generate ephemeral X25519 keypair for this submission.
+    const ephemeral = await crypto.subtle.generateKey(
+        { name: "ECDH", namedCurve: "X25519" },
+        true,
+        ["deriveKey", "deriveBits"]
+    );
+
+    // Import server's X25519 public key.
+    const serverKey = await crypto.subtle.importKey(
+        "raw",
+        serverPubBytes,
+        { name: "ECDH", namedCurve: "X25519" },
+        false,
+        []
+    );
+
+    // ECDH key agreement → 32-byte shared secret.
+    const sharedBits = await crypto.subtle.deriveBits(
+        { name: "ECDH", public: serverKey },
+        ephemeral.privateKey,
+        256
+    );
+
+    // Derive AES-GCM-256 key via HKDF-SHA-256.
+    const hkdfKey = await crypto.subtle.importKey("raw", sharedBits, "HKDF", false, ["deriveKey"]);
+    const aesKey = await crypto.subtle.deriveKey(
+        {
+            name: "HKDF",
+            hash: "SHA-256",
+            salt: new Uint8Array(32),
+            info: new TextEncoder().encode("nymdrop-v1")
+        },
+        hkdfKey,
+        { name: "AES-GCM", length: 256 },
+        false,
+        ["encrypt"]
+    );
+
+    // Encrypt plaintext.
+    const iv = crypto.getRandomValues(new Uint8Array(12));
+    const ciphertext = await crypto.subtle.encrypt(
+        { name: "AES-GCM", iv },
+        aesKey,
+        new TextEncoder().encode(plaintext)
+    );
+
+    // Export ephemeral X25519 public key (32 bytes raw).
+    const ephemeralPubRaw = await crypto.subtle.exportKey("raw", ephemeral.publicKey);
+
+    // Packet layout: ephemeral_pub(32) + iv(12) + ciphertext
+    const packet = new Uint8Array(32 + 12 + ciphertext.byteLength);
+    packet.set(new Uint8Array(ephemeralPubRaw), 0);
+    packet.set(iv, 32);
+    packet.set(new Uint8Array(ciphertext), 44);
+
+    return packet;
+}
+
+document.getElementById("drop-form").addEventListener("submit", async (e) => {
+    e.preventDefault();
+    const status = document.getElementById("status");
+    status.className = "";
+    status.textContent = "Encrypting...";
+
+    try {
+        let plaintext = document.getElementById("message").value;
+
+        const fileInput = document.getElementById("file");
+        if (fileInput.files.length > 0) {
+            const fileBytes = await fileInput.files[0].arrayBuffer();
+            const fileB64 = btoa(String.fromCharCode(...new Uint8Array(fileBytes)));
+            plaintext += "\n---FILE:" + fileInput.files[0].name + "---\n" + fileB64;
+        }
+
+        const encrypted = await encryptPayload(plaintext);
+
+        const resp = await fetch("/submit", {
+            method: "POST",
+            headers: { "Content-Type": "application/octet-stream" },
+            body: encrypted,
+        });
+
+        if (resp.ok) {
+            document.getElementById("drop-form").reset();
+            document.getElementById("filename").textContent = "";
+            status.textContent = "Delivered. No record of this submission exists on the server.";
+        } else {
+            status.className = "error";
+            status.textContent = "Delivery failed. Try again.";
+        }
+    } catch (err) {
+        status.className = "error";
+        status.textContent = "Encryption failed: " + err.message;
+    }
+});
diff --git a/static/index.html b/static/index.html
new file mode 100644
index 0000000..c957a01
--- /dev/null
+++ b/static/index.html
@@ -0,0 +1,61 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta name="referrer" content="no-referrer">
+    <title>NymDrop — Secure Submission</title>
+    <link rel="stylesheet" href="/style.css">
+</head>
+<body>
+<div class="card">
+
+    <div class="logo">
+        <div class="logo-icon">⬡</div>
+        <h1>NYMDROP</h1>
+    </div>
+    <p class="tagline">Anonymous document submission — encrypted in your browser, delivered over Nym mixnet.</p>
+
+    <div class="badges">
+        <span class="badge badge-green">END-TO-END ENCRYPTED</span>
+        <span class="badge badge-blue">NYM MIXNET</span>
+        <span class="badge badge-gray">NO LOGS</span>
+        <span class="badge badge-gray">NO METADATA</span>
+    </div>
+
+    <form id="drop-form">
+        <label for="message">Message</label>
+        <textarea id="message" placeholder="Write your message here. It will be encrypted before leaving your browser."></textarea>
+
+        <div class="file-section">
+            <label>Attachment (optional)</label>
+            <label class="file-label" for="file">&#128206; Choose file</label>
+            <input type="file" id="file">
+            <span id="filename"></span>
+        </div>
+
+        <button type="submit" class="submit-btn">&#128274; Submit securely</button>
+    </form>
+
+    <div id="status"></div>
+
+    <hr class="divider">
+
+    <p class="notice">
+        <span>Your submission is encrypted in this browser before being sent.</span>
+        The server never sees the content and retains no logs.
+        Once delivered over the Nym mixnet, no record of this submission exists on this server.
+        For maximum anonymity, submit from a public network.
+    </p>
+
+</div>
+<div class="footer">NYMDROP &nbsp;·&nbsp; ZERO KNOWLEDGE &nbsp;·&nbsp; ZERO LOGS</div>
+<script src="/crypto.js"></script>
+<script>
+    document.getElementById('file').addEventListener('change', function() {
+        const name = this.files.length ? this.files[0].name : '';
+        document.getElementById('filename').textContent = name;
+    });
+</script>
+</body>
+</html>
diff --git a/static/style.css b/static/style.css
new file mode 100644
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--- /dev/null
+++ b/static/style.css
@@ -0,0 +1,179 @@
+*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
+
+body {
+    background: #0d1117;
+    color: #c9d1d9;
+    font-family: 'Courier New', Courier, monospace;
+    min-height: 100vh;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    padding: 2rem 1rem;
+}
+
+.card {
+    background: #161b22;
+    border: 1px solid #21262d;
+    border-radius: 8px;
+    padding: 2.5rem 2rem;
+    width: 100%;
+    max-width: 580px;
+    box-shadow: 0 0 40px rgba(0,255,160,0.04);
+}
+
+.logo {
+    display: flex;
+    align-items: center;
+    gap: 0.7rem;
+    margin-bottom: 0.5rem;
+}
+
+.logo-icon {
+    width: 32px;
+    height: 32px;
+    background: linear-gradient(135deg, #00ffa0, #0080ff);
+    border-radius: 6px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    font-size: 1rem;
+    color: #0d1117;
+    font-weight: bold;
+}
+
+h1 {
+    font-size: 1.4rem;
+    font-weight: bold;
+    color: #e6edf3;
+    letter-spacing: 0.15em;
+}
+
+.tagline {
+    font-size: 0.72rem;
+    color: #484f58;
+    margin-bottom: 2rem;
+    letter-spacing: 0.03em;
+}
+
+.badges {
+    display: flex;
+    gap: 0.5rem;
+    margin-bottom: 2rem;
+    flex-wrap: wrap;
+}
+
+.badge {
+    font-size: 0.65rem;
+    padding: 0.2rem 0.6rem;
+    border-radius: 20px;
+    letter-spacing: 0.05em;
+    font-weight: bold;
+}
+
+.badge-green { background: rgba(0,255,160,0.08); color: #00ffa0; border: 1px solid rgba(0,255,160,0.2); }
+.badge-blue  { background: rgba(0,128,255,0.08); color: #58a6ff; border: 1px solid rgba(0,128,255,0.2); }
+.badge-gray  { background: rgba(255,255,255,0.04); color: #8b949e; border: 1px solid #30363d; }
+
+label {
+    display: block;
+    font-size: 0.72rem;
+    color: #8b949e;
+    margin-bottom: 0.4rem;
+    text-transform: uppercase;
+    letter-spacing: 0.08em;
+}
+
+textarea {
+    width: 100%;
+    height: 160px;
+    background: #0d1117;
+    border: 1px solid #30363d;
+    border-radius: 6px;
+    color: #c9d1d9;
+    font-family: 'Courier New', Courier, monospace;
+    font-size: 0.88rem;
+    padding: 0.9rem;
+    resize: vertical;
+    margin-bottom: 1.4rem;
+    transition: border-color 0.2s;
+    outline: none;
+}
+
+textarea:focus { border-color: #00ffa0; box-shadow: 0 0 0 2px rgba(0,255,160,0.08); }
+
+.file-section { margin-bottom: 1.8rem; }
+
+.file-label {
+    display: inline-block;
+    background: #21262d;
+    border: 1px solid #30363d;
+    border-radius: 6px;
+    color: #8b949e;
+    font-size: 0.78rem;
+    padding: 0.5rem 1rem;
+    cursor: pointer;
+    transition: border-color 0.2s, color 0.2s;
+}
+
+.file-label:hover { border-color: #58a6ff; color: #58a6ff; }
+
+#file { display: none; }
+
+#filename {
+    font-size: 0.72rem;
+    color: #58a6ff;
+    margin-left: 0.6rem;
+    vertical-align: middle;
+}
+
+.submit-btn {
+    width: 100%;
+    background: linear-gradient(135deg, #00ffa0 0%, #0080ff 100%);
+    border: none;
+    border-radius: 6px;
+    color: #0d1117;
+    font-family: 'Courier New', Courier, monospace;
+    font-size: 0.9rem;
+    font-weight: bold;
+    letter-spacing: 0.1em;
+    padding: 0.85rem;
+    cursor: pointer;
+    transition: opacity 0.2s, transform 0.1s;
+    text-transform: uppercase;
+}
+
+.submit-btn:hover { opacity: 0.9; }
+.submit-btn:active { transform: scale(0.99); }
+
+#status {
+    margin-top: 1rem;
+    font-size: 0.78rem;
+    min-height: 1.2rem;
+    text-align: center;
+    color: #00ffa0;
+}
+
+#status.error { color: #f85149; }
+
+.divider {
+    border: none;
+    border-top: 1px solid #21262d;
+    margin: 2rem 0 1.2rem;
+}
+
+.notice {
+    font-size: 0.68rem;
+    color: #3d444d;
+    line-height: 1.7;
+}
+
+.notice span { color: #484f58; }
+
+.footer {
+    margin-top: 1.5rem;
+    font-size: 0.62rem;
+    color: #21262d;
+    text-align: center;
+    letter-spacing: 0.05em;
+}