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.
Follow these steps to generate the hash:
  1. Generate the SHA-256 hash of the JSON payload (body of the message).
  2. Encode the hashed string to Base64.
  3. Add the message body hash to the
    digest
     payload field.
  4. Add the hash algorithm used to the
    digestAlgorithm
     payload field.

Example: Digest Header Field

digest: RBNvo1WzZ4oRRq0W9+hknpT7T8If536DEMBg9hyq/4o=

Example: DigestAlgorithm Header Field

digestAlgorithm: SHA-256

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);
}