Generating a Hash of the Message Body

This hash is used to validate the integrity of the message at the receiving end.

Follow these steps to generate the hash:

Generate the SHA-256 hash of the JSON payload (body of the message).

Encode the hashed string to Base64.

Prepend

SHA-256=

to the front of the hash.

Add the message body hash to the

digest

header field.

Example: Digest Header Field

digest: SHA-256=NmFlNTQ1OWJjOGE3ZDZhNGIyMDNlOGE3MzRkNmE2MTY3MjUxMzQwODhlMTMyNjFmNWJiY2VmYzE0MjRmYzk1Ng==

Code Example: Creating a Message Hash Using Command Line Tools

Generate the SHA-256 hash using the

shasum

tool.

echo -n "{"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":"[email protected]","phoneNumber":"4158880000"}}}" | shasum -a 256

Base64-encode the hash value using the

base64

tool.

echo -n "6ae5459bc8a7d6a4b203e8a734d6a616725134088e13261f5bbcefc1424fc956" | base64

Code 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);
         digest = "SHA-256=" + digest;
     }
     return digest;
}

Code 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 "SHA-256=" + Base64.getEncoder().encodeToString(digest);
}