Signing Algorithm

Steps

1. Collect all request parameters (excluding sign) and sort by key in ASCII order
2. Concatenate sorted parameters as key1=value1&key2=value2&...
3. Append &appSecret=yourAppSecret at the end
4. Compute the MD5 hash (lowercase hexadecimal) of the entire string — this is the sign value

Example

Given the following parameters:

Parameter	Value
appKey	abc123
language	zh-CN
timestamp	1700000000

App Secret is my_secret_key

Step 1: Sort and concatenate by ASCII order

appKey=abc123&language=zh-CN&timestamp=1700000000

Step 2: Append appSecret

appKey=abc123&language=zh-CN&timestamp=1700000000&appSecret=my_secret_key

Step 3: Compute MD5

sign = MD5("appKey=abc123&language=zh-CN&timestamp=1700000000&appSecret=my_secret_key")

Code Examples

Java

import java.security.MessageDigest;
import java.util.Map;
import java.util.TreeMap;

public class LoxilySign {
    public static String generateSign(Map<String, String> params, String appSecret) throws Exception {
        TreeMap<String, String> sorted = new TreeMap<>(params);
        sorted.remove("sign");

        StringBuilder sb = new StringBuilder();
        for (Map.Entry<String, String> entry : sorted.entrySet()) {
            if (sb.length() > 0) sb.append("&");
            sb.append(entry.getKey()).append("=").append(entry.getValue());
        }
        sb.append("&appSecret=").append(appSecret);

        MessageDigest md = MessageDigest.getInstance("MD5");
        byte[] digest = md.digest(sb.toString().getBytes("UTF-8"));
        StringBuilder hex = new StringBuilder();
        for (byte b : digest) {
            hex.append(String.format("%02x", b));
        }
        return hex.toString();
    }
}

Python

import hashlib

def generate_sign(params: dict, app_secret: str) -> str:
    filtered = {k: v for k, v in params.items() if k != "sign"}
    sorted_keys = sorted(filtered.keys())
    sign_str = "&".join(f"{k}={filtered[k]}" for k in sorted_keys)
    sign_str += f"&appSecret={app_secret}"
    return hashlib.md5(sign_str.encode("utf-8")).hexdigest()

JavaScript / Node.js

const crypto = require('crypto');

function generateSign(params, appSecret) {
  const keys = Object.keys(params)
    .filter(k => k !== 'sign')
    .sort();

  const parts = keys.map(k => `${k}=${params[k]}`);
  parts.push(`appSecret=${appSecret}`);

  return crypto.createHash('md5')
    .update(parts.join('&'), 'utf8')
    .digest('hex');
}

Go

package main

import (
    "crypto/md5"
    "fmt"
    "sort"
    "strings"
)

func GenerateSign(params map[string]string, appSecret string) string {
    keys := make([]string, 0, len(params))
    for k := range params {
        if k != "sign" {
            keys = append(keys, k)
        }
    }
    sort.Strings(keys)

    parts := make([]string, 0, len(keys)+1)
    for _, k := range keys {
        parts = append(parts, fmt.Sprintf("%s=%s", k, params[k]))
    }
    parts = append(parts, fmt.Sprintf("appSecret=%s", appSecret))

    data := strings.Join(parts, "&")
    return fmt.Sprintf("%x", md5.Sum([]byte(data)))
}