Generate Signature

This section describes how to generate the signature required by the Dubbing SDK for authentication.
Important: Signature generation must be performed on your server, never on the client, to avoid leaking the secretKey.

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1. Preparation: Keys (accessKey / secretKey)

caution

Please contact us to obtain the keys required to integrate and launch your project.

The Dubbing SDK uses paired keys:

• accessKey — Works like an account identifier. It will be transmitted.
• secretKey — Works like a password. Never expose or transmit it to clients.

Your server must provide a signature-generation endpoint.
Clients request the signature → server generates it → server returns it to clients.

If the secretKey is compromised, the administrator must replace the key immediately.

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2. Build the Signature String

The signature string consists of three lines, each ending with a newline (\n):

timestamp

nonce

userId

Step 1 — Generate timestamp

Current Unix timestamp in seconds.

Example command:

date +%s

Example value:

1676546987

Step 2 — Generate a random nonce

The nonce should be a random string. Example:

hexdump -n 16 -e '4/4 "%08X" 1 "\n"' /dev/random

Example output:

1E7889295850730393A955964821CAF6

Step 3 — User ID

Example: 518

Step 4 — Combine to form signature string:

1676546987

1E7889295850730393A955964821CAF6

518

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3. Compute Signature Value

Use HMAC-SHA1 with your secretKey, then Base64-URL encode the result.

Example signature:

B3W62RX1D4uJCJlRCX_SFuMevrw=

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4. Construct Final Signature Token

Format:

key="value",key="value",...

Fields:

• access_key
• timestamp
• nonce
• id (userId)
• signature

Example:

access_key="abcde",timestamp="1676546987",nonce="1E7889295850730393A955964821CAF6",id="518",signature="B3W62RX1D4uJCJlRCX_SFuMevrw="

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5. Server-Side Example Code (Java)

package org.example;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.util.Base64;

public class DubbingTokenDemo {
    public static void main(String[] args) {
        long time = getTimestamp();
        String nonce = buildNonce();
        String userId = "518";
        String data = buildData(time, nonce, userId);
        String signature = encrypt(data, secretKey);
        String token = buildToken(accessKey, time, nonce, userId, signature);
        System.out.println(signature);
        System.out.println(token);
    }

    public static final String HMAC_SHA1 = "HmacSHA1";
    public static final String SYMBOLS = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    public static final SecureRandom RANDOM = new SecureRandom();
    public static final String secretKey = "123456";
    public static final String accessKey = "abcde";

    public static String buildNonce() {
        char[] nonceChars = new char[16];
        for (int index = 0; index < nonceChars.length; ++index) {
            nonceChars[index] = SYMBOLS.charAt(RANDOM.nextInt(SYMBOLS.length()));
        }
        return new String(nonceChars);
    }

    public static long getTimestamp() {
        return System.currentTimeMillis() / 1000;
    }

    public static String buildData(long timestamp, String randomStr, String userId) {
        return timestamp + "\n" + randomStr + "\n" + userId + "\n";
    }

    private static String encrypt(String data, String key) {
        SecretKeySpec secret = new SecretKeySpec(key.getBytes(StandardCharsets.UTF_8), HMAC_SHA1);
        try {
            Mac mac = Mac.getInstance(HMAC_SHA1);
            mac.init(secret);
            return Base64.getUrlEncoder().encodeToString(mac.doFinal(data.getBytes()));
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("HMAC_SHA1 is not supported in the current Java environment", e);
        } catch (InvalidKeyException e) {
            throw new RuntimeException("Invalid secret key", e);
        }
    }

    public static String buildToken(String accessKey, long timestamp, String nonce, String userId, String signature) {
        String tokenStr = "access_key=\"%s\",timestamp=\"%s\",nonce=\"%s\",id=\"%s\",signature=\"%s\"";
        return String.format(tokenStr, accessKey, timestamp, nonce, userId, signature);
    }
}