Generate a Hash of the Message Body

Generate a Base64-encoded SHA-256 hash of the message, and place the hash in the header's

digest

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

To generate the hash:

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

Encode the hashed string to Base64.

Add the message body hash to the

digest

header field.

Add the hash algorithm used into the

digestAlgorithm

header field.

Example Digest Header Field

digest: NmFlNTQ1OWJjOGE3ZDZhNGIyMDNlOGE3MzRkNmE2MTY3MjUxMzQwODhlMTMyNjFmNWJiY2VmYzE0MjRmYzk1Ng==

Example DigestAlgorithm Header Field

digestAlgorithm: SHA-256

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":"smartpayfusetest@barclaycard.co.uk","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 = 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 Base64.getEncoder().encodeToString(digest);
}