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Step 3C: Set the JWS Body Claims

After you set the JWS header values, you must create the JWS body by setting these body claim values. After the body claims are created, use Base64URL to encode it. The encoded body claim value is the second segment of the JWS token.
JWS Body Claims
JWS Body Claim Field
Description
Data Type
Field Value Format
digest
A Base64-encoded hash of the message payload.
Do not include the
digest
 field if the request message is empty, such as during a GET or DELETE request.
String
Base64-encoded string: uppercase, lowercase, digits,
+
,
/
, and optional
=
 padding
digestAlgorithm
The algorithm used to hash the message payload.
The message payload should be hashed using the SHA-256 algorithm.
Do not include the
digestAlgorithm
 field if the
digest
 field is not included.
String
Lowercase
exp
The time at which the JWS token expires.
IMPORTANT
Field values cannot exceed two minutes after the message issue date, which is the
iat
 field value.
This field is an HTTP-date value as defined in RFC7231. For example, 01/01/2020 at 00:02:00 is
1577836920
.
String
Numeric
iat
The date and time at which the message is issued. This field uses a
NumericDate
 value as defined in RFC 7519, which is the number of seconds since
1970‑01‑01T00:00:00Z
 (Unix epoch).
For example, 01/01/2020 at 00:00:00 is
1577836800
.
String
Numeric
iss
The issuer identifier for the JWS token. Set to the merchant ID that created the P12 certificate. This value is used to validate the issuer.
String
Lowercase
jti
The unique token ID. This value is used for replay prevention.
Format the value using UUID version 4. For example:
6643fb9a-8093-47c6-95d3-8d69785b5e62
String
Lowercase alphanumeric
request-host
The endpoint hostname for the HTTP request, excluding the protocol and path.
For example, to send a message to the
https://nabgateway-api.nab.com.au
/pts/v2/payments
 endpoint, set this field to
nabgateway-api.nab.com.au
.
String
Lowercase alphanumeric with periods
request-method
The HTTP request method. For example,
post
,
get
,
put
,
patch
, or
delete
.
String
Lowercase
request-resource-path
The endpoint path for the HTTP request, excluding the domain.
For example, to send a message to the
https://nabgateway-api.nab.com.au
/pts/v2/payments
 endpoint, set this field to
/pts/v2/payments
.
String
Lowercase alphanumeric
v-c-jwt-version
The Visa JWT scheme version number. Set to
2
.
String
Numeric
v-c-merchant-id
Your
National Australia Bank
 transacting merchant ID (MID).
If you are a portfolio or merchant account user, set this to the transacting merchant ID you send requests on behalf of.
String
Lowercase alphanumeric
v-c-response-mle-kid
The message-level encryption response key ID, also known as the
REST–API Response MLE
 key.
String
Lowercase alphanumeric
The value of the
digest
 JWS claim is a hashed version of the HTTP message body that you must calculate.
National Australia Bank
 uses this hash value to validate the integrity of your message body.
Follow these steps to calculate the digest hash:
  1. Generate the SHA-256 hash of the JSON payload (message body).
  2. Encode the hashed string to Base64.
  3. Add the message body hash to the
    digest
     JWS body claims.
  4. Add the algorithm used to hash the digest in the
    digestAlgorithm
     JWS body claims.
Example: Creating a Message Hash Using the Command Line
shasum
 Tool
cat <<'EOF' | tr -d '\n' | shasum -a 256
{
  "clientReferenceInformation": {
    "code": "TC50171_3"
  },
  "paymentInformation": {
    "card": {
      "number": "4111111111111111",
      "expirationMonth": "12",
      "expirationYear": "2031"
    }
  },
  "orderInformation": {
    "amountDetails": {
      "totalAmount": "102.21",
      "currency": "USD"
    },
    "billTo": {
      "firstName": "John",
      "lastName": "Doe",
      "address1": "1MarketSt",
      "locality": "sanfrancisco",
      "administrativeArea": "CA",
      "postalCode": "94105",
      "country": "US",
      "email": "",
      "phoneNumber": "4158880000"
    }
  }
}
EOF
Example: Creating a Message Hash Using the Command Line
base64
 Tool
echo -n "6ae5459bc8a7d6a4b203e8a734d6a616725134088e13261f5bbcefc1424fc956" | base64
Example: Creating a Message Hash Using C#
public static string GenerateDigest()
{
    var digest = "";
    var bodyText = "{ your JSON payload }";

    using (var sha256hash = SHA256.Create())
    {
        byte[] payloadBytes = sha256hash.ComputeHash(Encoding.UTF8.GetBytes(bodyText));
        digest = Convert.ToBase64String(payloadBytes);
    }

    return digest;
}
Example: Creating a Message Using Java
public static String GenerateDigest() throws NoSuchAlgorithmException {
    String bodyText = "{ your JSON payload }";

    MessageDigest md = MessageDigest.getInstance("SHA-256");
    md.update(bodyText.getBytes(StandardCharsets.UTF_8));
    byte[] digest = md.digest();

    return Base64.getEncoder().encodeToString(digest);
}
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