Authentication

BiuLinkPay Signature Verification Technical Specification

Signature Generation Mechanism

The system employs HMAC-SHA512 algorithm to generate request signatures, ensuring the integrity and authenticity of transaction requests. The signature process strictly adheres to the following technical specifications:

Core Parameters

• Encryption Algorithm: HMAC-SHA512

• Character Encoding: UTF-8

• Output Format: Uppercase hexadecimal string

Signature Generation Process

1. Data Preparation Phase:

   • Convert the content to be signed into UTF-8 encoded byte array

   • Obtain merchant security key (secretKey)

2. Encryption Processing Phase:

   • Initialize HMAC-SHA512 encryption instance

   • Generate encryption key using security key

   • Perform encryption operation on raw data

3. Format Conversion Phase:

   • Convert encrypted result byte array to hexadecimal string

   • Output is uniformly converted to uppercase

Key Technical Implementation Points

1. Encoding Standards:

   • Strictly use UTF-8 character encoding for string processing

   • Apply 0xFF mask during byte conversion to ensure unsigned conversion

2. Security Features:

   • Adopts 512-bit strong hash algorithm

   • Separate processing of keys and data

   • Tamper-proof design: Any parameter changes will invalidate the signature

3. Performance Optimization:

   • Uses static character array to improve hexadecimal conversion efficiency

   • Predefined encryption algorithm instances avoid repeated initialization

Important Notes

1. Key Management:

   • Security keys must remain strictly confidential

   • Regular key rotation recommended

   • Hardcoding keys in client-side code is prohibited

2. Signature Verification:

   • Server must use same algorithm and parameters to verify signatures

   • Recommended timestamp validity window: ±5 minutes

   • Random strings (nonce) must ensure uniqueness

3. Exception Handling:

   • Must handle invalid encoding exceptions

   • Clear exceptions should be thrown when encryption algorithm is unavailable

   • Null inputs should be properly intercepted

Sign Example For Java

public static void main(String[] args) throws Exception {
        String nonce = UUID.randomUUID().toString().replace("-", "");

        Map<String, Object> jsonMap = new HashMap<>();
        jsonMap.put("tradeNo", "7788991111711116");

        Gson gson = new Gson();

        HttpUtil httpUtil = new HttpUtil();

        String currentTime = String.valueOf(System.currentTimeMillis());

        String sendJson = gson.toJson(jsonMap);
        String payload = currentTime + "\n" + nonce + "\n" + sendJson + "\n";

        Map<String, String> headers = new HashMap<String, String>();

        headers.put("BiuLinkPay-AppId", "FEA21349995B45929AA26EC1AB6C1DA0");
        headers.put("BiuLinkPay-TimeStamp", currentTime);
        headers.put("BiuLinkPay-Nonce", nonce);
        headers.put("BiuLinkPay-Signature", signature("Eh1+2XmwSWZ8HJ8a98okMIux6GqWHZRPhe1vAwb8ziI=", payload));

        String result = httpUtil.post("https://api.biulink.online/api/pay/merchant/paymentQuery", sendJson, headers).getBody();
        System.out.println(result);
}
    
private static String signature(String secretKey, String payload) throws Exception {
    byte[] bytes = payload.getBytes(StandardCharsets.UTF_8);
    byte[] hmacBytes = HmacSha512(bytes, secretKey);
    return byteArrayToHexStr(hmacBytes).toUpperCase();
}

private static byte[] HmacSha512(byte[] binaryData, String key) throws Exception {
    Mac mac = Mac.getInstance("HmacSHA512");
    SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), "HmacSHA512");
    mac.init(secretKey);
    byte[] HmacSha1Digest = mac.doFinal(binaryData);
    return HmacSha1Digest;
}

private static String byteArrayToHexStr(byte[] byteArray) {
    if (byteArray == null) {
        return null;
    }
    char[] hexArray = "0123456789ABCDEF".toCharArray();
    char[] hexChars = new char[byteArray.length * 2];
    for (int j = 0; j < byteArray.length; j++) {
        int v = byteArray[j] & 0xFF;
        hexChars[j * 2] = hexArray[v >>> 4];
        hexChars[j * 2 + 1] = hexArray[v & 0x0F];
    }
    return new String(hexChars);
}