ElevenLabs Security Basics

Overview

Security best practices for ElevenLabs API key management, webhook HMAC signature verification, and protecting cloned voice data. ElevenLabs uses a single API key (xi-api-key) and HMAC webhook authentication.

Prerequisites

• ElevenLabs SDK installed
• Understanding of environment variables
• Access to ElevenLabs dashboard (Settings > API Keys)

Instructions

Step 1: API Key Management

# .env (NEVER commit to git)
ELEVENLABS_API_KEY=sk_your_key_here

# .gitignore — MUST include these
.env
.env.local
.env.*.local

Git pre-commit hook to prevent accidental key commits:

#!/bin/bash
# .git/hooks/pre-commit
if git diff --cached | grep -qE 'sk_[a-zA-Z0-9]{20,}'; then
  echo "ERROR: ElevenLabs API key detected in staged changes!"
  echo "Remove the key and use environment variables instead."
  exit 1
fi

Step 2: Environment-Specific Keys

// src/elevenlabs/config.ts
interface ElevenLabsSecurityConfig {
  apiKey: string;
  webhookSecret: string;
  environment: "development" | "staging" | "production";
}

export function getSecurityConfig(): ElevenLabsSecurityConfig {
  const env = (process.env.NODE_ENV || "development") as ElevenLabsSecurityConfig["environment"];

  const apiKey = process.env.ELEVENLABS_API_KEY;
  if (!apiKey) {
    throw new Error("ELEVENLABS_API_KEY is required");
  }

  // Warn if production key is used in dev
  if (env === "development" && apiKey.startsWith("sk_live_")) {
    console.warn("WARNING: Using production API key in development environment");
  }

  return {
    apiKey,
    webhookSecret: process.env.ELEVENLABS_WEBHOOK_SECRET || "",
    environment: env,
  };
}

Step 3: Webhook HMAC Signature Verification

ElevenLabs webhooks include an ElevenLabs-Signature header for HMAC verification:

// src/elevenlabs/webhook-verify.ts
import crypto from "crypto";

/**
 * Verify ElevenLabs webhook signature using HMAC-SHA256.
 * The shared secret is generated when you create a webhook in the dashboard.
 */
export function verifyWebhookSignature(
  payload: string | Buffer,
  signatureHeader: string,
  secret: string
): boolean {
  if (!signatureHeader || !secret) return false;

  // ElevenLabs signature format: t=<timestamp>,v1=<signature>
  const parts = signatureHeader.split(",");
  const timestamp = parts.find(p => p.startsWith("t="))?.slice(2);
  const signature = parts.find(p => p.startsWith("v1="))?.slice(3);

  if (!timestamp || !signature) return false;

  // Reject timestamps older than 5 minutes (replay protection)
  const age = Math.floor(Date.now() / 1000) - parseInt(timestamp);
  if (age > 300) {
    console.error("Webhook timestamp too old:", age, "seconds");
    return false;
  }

  // Compute expected HMAC
  const signedPayload = `${timestamp}.${payload.toString()}`;
  const expected = crypto
    .createHmac("sha256", secret)
    .update(signedPayload)
    .digest("hex");

  // Timing-safe comparison to prevent timing attacks
  try {
    return crypto.timingSafeEqual(
      Buffer.from(signature, "hex"),
      Buffer.from(expected, "hex")
    );
  } catch {
    return false;
  }
}

Step 4: Express Webhook Endpoint with Verification

import express from "express";
import { verifyWebhookSignature } from "./webhook-verify";

const app = express();

// IMPORTANT: Must use raw body for signature verification
app.post("/webhooks/elevenlabs",
  express.raw({ type: "application/json" }),
  (req, res) => {
    const signature = req.headers["elevenlabs-signature"] as string;
    const secret = process.env.ELEVENLABS_WEBHOOK_SECRET!;

    if (!verifyWebhookSignature(req.body, signature, secret)) {
      console.error("Webhook signature verification failed");
      return res.status(401).json({ error: "Invalid signature" });
    }

    const event = JSON.parse(req.body.toString());

    // Return 200 quickly to acknowledge receipt
    // Process asynchronously to avoid webhook timeout/disable
    res.status(200).json({ received: true });

    processWebhookAsync(event).catch(console.error);
  }
);

Step 5: API Key Rotation Procedure

# 1. Generate new API key in ElevenLabs dashboard
#    Settings > API Keys > Create new key

# 2. Test new key before rotating
curl -s https://api.elevenlabs.io/v1/user \
  -H "xi-api-key: sk_new_key_here" | jq '.subscription.tier'

# 3. Update in all environments
# Vercel:
vercel env add ELEVENLABS_API_KEY production

# Fly.io:
fly secrets set ELEVENLABS_API_KEY=sk_new_key_here

# GitHub Actions:
gh secret set ELEVENLABS_API_KEY --body "sk_new_key_here"

# 4. Deploy with new key
# 5. Verify production works
# 6. Delete old key in ElevenLabs dashboard

Step 6: Voice Data Protection

// Cloned voices contain biometric data — treat as PII
const voiceSecurityPolicy = {
  // Restrict who can create/delete cloned voices
  clonePermissions: "admin_only",

  // Log all voice cloning operations
  auditCloning: true,

  // Require consent documentation before cloning
  consentRequired: true,

  // Auto-delete test clones after N days
  testVoiceTtlDays: 30,
};

// Audit log for voice operations
function logVoiceOperation(operation: string, voiceId: string, userId: string) {
  console.log(JSON.stringify({
    timestamp: new Date().toISOString(),
    type: "elevenlabs.voice.audit",
    operation,  // "clone", "delete", "use"
    voiceId,
    userId,
  }));
}

Security Checklist

• API keys in environment variables (never in source code)
• .env files in .gitignore
• Different API keys for dev/staging/prod
• Pre-commit hook scanning for key patterns (sk_)
• Webhook signatures verified with HMAC-SHA256
• Replay protection on webhooks (5-minute timestamp check)
• Webhook failures monitored (auto-disabled after 10 consecutive failures)
• Voice cloning operations audit-logged
• Cloned voice consent documented
• API key rotation scheduled quarterly

Webhook Failure Policy

ElevenLabs auto-disables webhooks after:

• 10+ consecutive delivery failures, AND
• Last successful delivery was 7+ days ago (or never delivered)

Always return HTTP 200 quickly from your webhook handler.

Error Handling

Security Issue	Detection	Mitigation
Exposed API key	Git scanning, CI check	Rotate immediately, revoke old key
Invalid webhook signature	verifyWebhookSignature() returns false	Log and reject (HTTP 401)
Replay attack	Timestamp > 5 minutes old	Reject with timestamp check
Unauthorized voice cloning	Audit logs	Restrict clone permissions

Resources

• ElevenLabs Webhooks
• ElevenLabs API Keys
• Voice Cloning Policy

Next Steps

For production deployment, see elevenlabs-prod-checklist.