• 0.1.0 (6 Nov 2019)
  • Initial Draft Release

The RESTful API adopts Semantic Versioning 2.0.0 for releases, and every new release of the API increments the version numbers in the following format:

{MAJOR}.{MINOR}.{PATCH}

1. {MAJOR} number introduces incompatible API changes with previous {MAJOR} number also resets {MINOR} to 0,
2. {MINOR} number introduces new functionalities or information that are backward compatible also resets {PATCH} to 0, and
3. {PATCH} number introduces bug fixes and remains backward compatible.

Pre-release or draft versions, when provided, are denoted by appended hypen - with a series of separate identifiers {LABEL}-{VERSION} following the {PATCH} number. Such releases are unstable and may not provide the intended compatibility with the specification in draft status.

Despite backward compatibility in {MINOR} or {PATCH} releases, API consumers are best to evaluate and determine their implementation does not disrupt use-case requirements.

The RESTful API provides both testing and live environments accessible over the Internet via HTTPS.

Consumers are to ensure firewall clearance on their edge network nodes for connecting to the APIs.

The convention used by API endpoints' URL are in the following format:

https://{ENV_DOMAIN_NAME}/{CONTEXT}/{VERSION}/{RESOURCE}

• {ENV_DOMAIN_NAME} indicates EDH's API domain names - respectively:

  • sandbox.api.edh.gov.sg, or
  • test.api.edh.gov.sg, or
  • api.edh.gov.sg, following

• /{CONTEXT}, indicates the context of the API call = /gov

• /{VERSION} indicates the endpoint's release {MAJOR} version number path - for this release = /v1

• /{RESOURCE} indicates the API resource path name.

Any additional query string parameters are appended as needed.

1. Sandbox Environment

The sandbox environment is used for your testing when developing your prototype. The Person Search API will return test data previously shared by our officer via email. For test data matters, please contact us.

Note:

• Domain Name: sandbox.api.edh.gov.sg
• PKI digital signature is not required for all APIs.

2. Test Environment

The test enviroment is used for testing your application with the full security measures required in production. The Licence Search API will return test data previously shared by our officer via email. For test data matters, please contact us.

Note:

• Domain Name: test.api.edh.gov.sg
• PKI digital signature is required for Licence Search APIs.
  Refer to Security > Request Signing for the steps to sign your request.

3. Production Environment

The production enviroment is the actual live environment with full security measures and live data.

Note:

• Domain Name: api.edh.gov.sg
• PKI digital signature is required for Licence Search APIs.
  Refer to Security > Request Signing for the steps to sign your request.

The following are the scheduled downtimes for the various environments:

Production Environment

• Once a month, Sunday 12:00 am to 8:00 am (date to be advised)

EDH's API gateway supports accessing of APIs via the following interfaces:

• HTTP version 1.1 connection over TLS (Transport Layer Security) version 1.1 or 1.2 standards, and ciphersuites:

  • using AES (Advanced Encryption Standard) and SHA (Secure Hash Algorithm),
  • on either GCM (Galois/Counter Mode) or CBC (Cipher Block Chaining) mode.

• Below is the list of recommended cipher suites that you may use:

  • TLS_RSA_WITH_AES_256_GCM_SHA384
  • TLS_RSA_WITH_AES_128_GCM_SHA256
  • TLS_RSA_WITH_AES_256_CBC_SHA256
  • TLS_RSA_WITH_AES_256_CBC_SHA
  • TLS_RSA_WITH_AES_128_CBC_SHA256
  • TLS_RSA_WITH_AES_128_CBC_SHA

IMPORTANT: ensure your server supports TLS 1.1 or 1.2 and supports a cipher suite in the list above.

Accessing the RESTful API using prior versions of TLS or unsupported ciphersuites will result in connectivity errors. EDH's API gateway does not support 2-way TLS client nor mutual authentication.

API HTTP interface features:

1. JSON (JavaScript Object Notation) is the supported data media format and indicated in Content-Type header application/json, also
2. Content-Length header is omitted by having Transfer-Encoding header chunked emitted for streaming data, and
3. GZip (GNU Zip) response compression is supported by opt-in Accept-Encoding: gzip and indicated in Content-Encoding header gzip.

Access to all server-to-server APIs will be authenticated by EDH's API gateway. Prior to consumption of API, respective consumers are required to have:

• approval of access, onboarding process for the required API resources will be provisioned, and
• authentication credentials are then supplied and exchanged.

Authentication methods provided by EDH's API gateway on internet:

• Digital signature should be produced using a RSA private key with corresponding public certificate issued by one of the following compatible CAs:
  • digiCert
  • Entrust
  • Comodo
  • VeriSign
  • GlobalSign
  • GeoTrust
  • Thawte

NOTE: Test and Production Environments only

All server-to-server API requests are to be digitally signed, by including the following parameters and values in the Authorization header:

PKI_SIGN app_id="{app_id}",
nonce="{random_nonce}",
signature_method="RS256",
signature="{base64_url_percent_encoded_signature}",
timestamp="{unix_epoch_in_milliseconds}"

Note: Above sample is separated by lines for ease-of-reading, and new-line denotations are to be omitted in the actual request.

• {app_id} is the APP ID credential supplied upon onboarding,

• {random_nonce} is an unique randomly generated text used for replay prevention,

• {signature_algorithm} is the signature algorithm of the authenticating gateway.

  • Value of signature_algorithm = RS256

• {base64_url_percent_encoded_signature} is the binary of the generated signature encoded in Base64 URL-safe format,

• {unix_epoch_in_milliseconds} is the UNIX epoch time in milliseconds

Sample header with authorization parameters

Below is an example of an Authorization header for the sample application. Make sure you list the parameters in the sequence shown below.

  Authorization: PKI_SIGN
  app_id="STG2-EDH-SELF-TEST",
  nonce="150590021034800",
  signature_method="RS256",
  signature="EEm+HEcNQajb5FkVd82zjojk+daYZXxSGPCOR2GHZeoyjZY1PK+aFMzHfWu7eJZYMa5WaEwWxdOdq5hjNbl8kHD7bMaOks7FgEPdjE++TNomfv7SMktDnIvZmPYAxhjb/C9POU2KT6tSlZT/Si/qMgD1cryaPwSeMoM59UZa1GzYmqlkveba7rma58uGwb3wZFH0n57UnouR6LYXDOOLkqi8uMZBuvRUvSJRXETAj2N0hT+4QJiN96Ct6IEQh/woZh0o74K5Ol9PpDSM08qC7Lj6N/k694J+hbBQVVviGn7/6mDkfbwdMDuoKs4t7NpqmAnwT+xaQSIZcexfrAVQYA==",
  timestamp="1505900210349"

Sample Code in NodeJS

  // generates the security headers for calling API gateway
  function generateAuthorizationHeader(url, params, method, strContentType, authType, appId, keyCertContent, passphrase) {

    if (authType == "L2") {
      return generateRS256Header(url, params, method, strContentType, appId, keyCertContent, passphrase);
    } else {
      return "";
    }
  };

  // Signing Your Requests
  function generateRS256Header(url, params, method, strContentType, appId, keyCertContent, keyCertPassphrase) {
    var nonceValue = nonce();
    var timestamp = (new Date).getTime();

    // A) Construct the Authorisation Token Parameters
    var defaultAuthHeaders = {
      "app_id": appId, // App ID assigned to your application
      "nonce": nonceValue, // secure random number
      "signature_method": "RS256",
      "timestamp": timestamp // Unix epoch time
    };

    // B) Forming the Base String
    // Base String is a representation of the entire request (ensures message integrity)

    // i) Normalize request parameters
    var baseParams = sortJSON(_.merge(defaultAuthHeaders, params));

    var baseParamsStr = qs.stringify(baseParams);
    baseParamsStr = qs.unescape(baseParamsStr); // url safe

    // ii) concatenate request elements (HTTP method + url + base string parameters)
    var baseString = method.toUpperCase() + "&" + url + "&" + baseParamsStr;

    // C) Signing Base String to get Digital Signature
    var signWith = {
      key: fs.readFileSync(keyCertContent, 'utf8')
    }; // Provides private key

    // Load pem file containing the x509 cert & private key & sign the base string with it to produce the Digital Signature
    var signature = crypto.createSign('RSA-SHA256')
      .update(baseString)
      .sign(signWith, 'base64');

    // D) Assembling the Authorization Header
    var strAuthHeader = "PKI_SIGN app_id=\"" + appId + // Defaults to 1st part of incoming request hostname
      "\",nonce=\"" + nonceValue +
      "\",signature_method=\"RS256\"" +
      ",signature=\"" + signature +
      "\",timestamp=\"" + timestamp +
      "\"";

    return strAuthHeader;
  };

NOTE: Licence Search APIs in Test and Production environments only

The response payload for the Licence Search API (for test and production environments) is first signed, then encrypted:

• Signing is done using JWS (JSON Web Signature) format
• Encryption is done using JWE (JSON Web Encryption) Compact Serialization format

Encryption protects the data at rest while a signed payload means, if necessary, you will be able to pass this signed payload to a 3rd party where they can verify the payload's integrity with our public certificate.

In order to read the payload, you have to perform the following steps in order:

1. Decrypt the payload with your application's private key.
2. Validate the decrypted payload signature with our public key.
3. Decode the verified JWS payload using Base64 decode.

After doing the above steps, your application will be able to extract the payload in JSON format.

STEP 1: Decryption

• Encryption is done using your application's public key that you provided during onboarding. Decryption of the payload should be using the private key of that key-pair.
• Current encryption algorithms used:
  • RSA-OAEP (for content key wrapping)
  • AES256GCM (for content encrytion)

Sample Code in NodeJS

  // Sample Code for decrypting JWE
  // Decrypt JWE using private key
  function decryptJWE(header, encryptedKey, iv, cipherText, tag, privateKey) {

    return new Promise((resolve, reject) => {

      var keystore = jose.JWK.createKeyStore();

      var data = {
        "type": "compact",
        "ciphertext": cipherText,
        "protected": header,
        "encrypted_key": encryptedKey,
        "tag": tag,
        "iv": iv,
        "header": JSON.parse(jose.util.base64url.decode(header).toString())
      };
      keystore.add(fs.readFileSync(privateKey, 'utf8'), "pem")
        .then(function(jweKey) {
          // {result} is a jose.JWK.Key
          jose.JWE.createDecrypt(jweKey)
            .decrypt(data)
            .then(function(result) {
              resolve(JSON.parse(result.payload.toString()));
            })
            .catch(function(error) {
              reject(error);
            });
        });

    })
    .catch (error => {
      throw "Error with decrypting JWE";
    })
  }

STEP 2: Verification of Signature

The decrypted payload is signed according to JWS (JSON Web Signature) format, similar to the access token.

• signature algorithm used is RS256.

Sample Code in NodeJS

  // Sample Code for Verifying & Decoding JWS or JWT
  function verifyJWS(jws, publicCert) {
    // verify payload
    // ignore notbefore check because it gives errors sometimes if the call is too fast.
    try {
      var decoded = jwt.verify(jws, fs.readFileSync(publicCert, 'utf8'), {
        algorithms: ['RS256'],
        ignoreNotBefore: true
      });
      return decoded;
    }
    catch(error) {
      throw("Error with verifying and decoding JWS");
    }
  }

EDH Licence Search data follows a specific structure that you need to understand to traverse the data effectively. This section will explain the structure in detail.

The diagram below illustrates how the data is represented logically:

Data Items are attributes that can be requested in the API. Each top-level data item can either be a data item object or an array of data item objects. Each data item object will consist of the following properties:

• source (see below)
• unavailable (in certain situations - see below)
• additional data properties containing data values or arrays

Data Source

The source property indicates the source of data. Possible values are:

• '1' - Government-verified

In each data item, there can be multiple data properties or arrays of data properties.

Each data property will contain either:

• a value property, or
• a pair of code and desc properties, or
• an array of data properties, or
• other data properties

Note:

• value property can be strings, numbers, or dates.
• code and desc pairs will contain the code and its matching description.
• value is mutually exclusive from (code + desc); i.e. if there is a value, there will not be any code or desc.
• Where there is code, there will always be a desc - no value will be present.

Exceptions: For these cases, the values will be directly in the property and not in a value, code or desc subproperty:

• for data item metadata properties; e.g. source and unavailable
• for discriminator properties; e.g. type in address formats

Sometimes, a requested data item or data property is not applicable to the person/entity/licence. For a full list, refer to the descriptions in each of the data properties of the Licence search data model.

Data Item Not Applicable

When a requested data item is not applicable to the person/entity/licence:

• for data item objects, the source property will be 3
• for data item arrays, an empty array will be returned

In such cases, please ignore the data item completely.

In other situations, a requested data item might not have any data for that data item from the data source; i.e. data is unavailable. Examples include:

• when an entity does not have any grants submitted/approved

Data Item Unavailable

• for data item objects, the data item will have the property unavailable with value true.
  In such cases, no additional properties (other than source) will be provided for the data item.
• for data item arrays, an empty array will be returned.

Please display as "Not Available" in your form.

Data Property Unavailable

• for data property objects, the value or code/desc will be empty value ("") or NaN.
• for arrays of data properties, an empty array will be returned.

The RESTful API(s) uses HTTP specification standard status codes to indicate the success or failure of each request. Except gateway errors, the response content will be in the following JSON format:

{
    "code": "integer (int32)",
    "message": "string"
}

Refer to the individual API definitions for the error codes you might encounter for each API.

Please refer to the links below for the following supporting materials where relevant:

• Code reference tables (for Licence Search objects)
• Test accounts for test environments (please contact us)

For technical queries, contact support@edh.gov.sg.

Licence Search API resource operations to access licence details.