(C) Verify an XML Signature with Multiple References

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

Chilkat C/C++ Library Downloads
MS Visual C/C++ Linux/CentOS C/C++ Alpine Linux C/C++ MAC OS X C/C++	armhf/aarch64 C/C++ C++ Builder iOS C/C++ Android C/C++	Solaris C/C++ MinGW C/C++

#include <C_CkHttp.h>
#include <C_CkStringBuilder.h>
#include <C_CkXmlDSig.h>

void ChilkatSample(void)
    {
    HCkHttp http;
    HCkStringBuilder sbXml;
    BOOL success;
    HCkXmlDSig verifier;
    BOOL verifyReferenceDigests;
    BOOL verified;
    BOOL signedInfoVerified;
    int numRefs;
    int i;
    BOOL refDigestVerified;

    // 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.
    http = CkHttp_Create();
    sbXml = CkStringBuilder_Create();
    success = CkHttp_QuickGetSb(http,"https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml",sbXml);
    if (success != TRUE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkHttp_Dispose(http);
        CkStringBuilder_Dispose(sbXml);
        return;
    }

    // Load the XML containing the signature to be verified.
    verifier = CkXmlDSig_Create();
    success = CkXmlDSig_LoadSignatureSb(verifier,sbXml);
    if (success != TRUE) {
        printf("%s\n",CkXmlDSig_lastErrorText(verifier));
        CkHttp_Dispose(http);
        CkStringBuilder_Dispose(sbXml);
        CkXmlDSig_Dispose(verifier);
        return;
    }

    verifyReferenceDigests = TRUE;

    // The quick way to validate all references and the signature over the SignedInfo
    // is to call VerifySignature with verifyReferenceDigests equal to TRUE.
    verified = CkXmlDSig_VerifySignature(verifier,verifyReferenceDigests);
    printf("Signature and all reference digests verified = %d\n",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;
    signedInfoVerified = CkXmlDSig_VerifySignature(verifier,verifyReferenceDigests);
    printf("Neglecting the reference hashes, the SignedInfo validation result = %d\n",signedInfoVerified);

    // We can also verify each reference digest separately
    numRefs = CkXmlDSig_getNumReferences(verifier);
    i = 0;
    while (i < numRefs) {
        refDigestVerified = CkXmlDSig_VerifyReferenceDigest(verifier,i);
        printf("Reference %d digest verified = %d\n",i,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


    CkHttp_Dispose(http);
    CkStringBuilder_Dispose(sbXml);
    CkXmlDSig_Dispose(verifier);

    }