(Java) Verify an XML Signature with Multiple References

Demonstrates how to verify an XML digital signature that contains multiple references.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // An example of an enveloping XML signature with mulitple references is available at
    // https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml

    // This example will show how to verify the signature and all references, and also how
    // to verify each reference individually.  This is useful to distinguish which part
    // of the XML signature validation failed.  It could be that one or more of the references
    // failed because of a hash computation mismatch.  Or it could be that the signature over
    // the SignedInfo failed.  

    // First, let's grab the sample XML signature.
    CkHttp http = new CkHttp();
    CkStringBuilder sbXml = new CkStringBuilder();
    boolean success = http.QuickGetSb("https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml",sbXml);
    if (success != true) {
        System.out.println(http.lastErrorText());
        return;
        }

    // Load the XML containing the signature to be verified.
    CkXmlDSig verifier = new CkXmlDSig();
    success = verifier.LoadSignatureSb(sbXml);
    if (success != true) {
        System.out.println(verifier.lastErrorText());
        return;
        }

    boolean verifyReferenceDigests = true;

    // The quick way to validate all references and the signature over the SignedInfo
    // is to call VerifySignature with verifyReferenceDigests equal to true.
    boolean verified = verifier.VerifySignature(verifyReferenceDigests);
    System.out.println("Signature and all reference digests verified = " + verified);

    // Let's pretend the call to VerifySignature returned false.  Something did not validate.
    // Was it one or more of the References that did not hash to the correct value?
    // Or was it the signature over the SignedInfo that failed?
    // We can check just the signature over the SignedInfo by passing false to VerifySignature.
    // This allows us to skip the hashing and checking each Reference.  
    verifyReferenceDigests = false;
    boolean signedInfoVerified = verifier.VerifySignature(verifyReferenceDigests);
    System.out.println("Neglecting the reference hashes, the SignedInfo validation result = " + signedInfoVerified);

    // We can also verify each reference digest separately
    int numRefs = verifier.get_NumReferences();
    int i = 0;
    while (i < numRefs) {
        boolean refDigestVerified = verifier.VerifyReferenceDigest(i);
        System.out.println("Reference " + i + " digest verified = " + refDigestVerified);
        i = i+1;
        }

    // For this sample XML signature with 3 References, we get the following output:

    // Signature and all reference digests verified = True
    // Neglecting the reference hashes, the SignedInfo validation result = True
    // Reference 0 digest verified = True
    // Reference 1 digest verified = True
    // Reference 2 digest verified = Tru
  }
}