(C) SII Chile - FRMT Signature Computation and Add to XML

Compute the FRMT signature and add to the XML. This is the RSA signature of the SHA-1 digest of the "flattened" DD element.

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#include <C_CkXml.h>
#include <C_CkStringBuilder.h>
#include <C_CkPrivateKey.h>
#include <C_CkRsa.h>

void ChilkatSample(void)
    {
    HCkXml xml;
    BOOL success;
    HCkXml ddXml;
    HCkStringBuilder sbFlattened;
    HCkPrivateKey privKey;
    HCkRsa rsa;
    const char *sig;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Also see:  Compute the FRMA Signature and Add to XML

    xml = CkXml_Create();

    // Load the unsigned XML that contains the following:

    // <DTE version="1.0">
    //   <Documento ID="F60T33">
    //         <TED version="1.0">
    //             <DD>
    // 		...
    //                 <CAF version="1.0">
    //                     <DA>
    // 			...
    //                     </DA>
    //                     <FRMA algoritmo="SHA1withRSA">...</FRMA>
    //                 </CAF>
    //                 ...
    //             </DD>
    //             ... The FRMT will be added here in another example ...
    //         </TED>
    //   </Documento>
    // </DTE>

    success = CkXml_LoadXmlFile(xml,"qa_data/xml_dsig/sii_cl/test_1.xml");
    if (success == FALSE) {
        printf("Failed to load initial XML file.\n");
        CkXml_Dispose(xml);
        return;
    }

    // Get a reference to the "DD" element
    ddXml = CkXml_FindChild(xml,"Documento|TED|DD");
    if (CkXml_getLastMethodSuccess(xml) == FALSE) {
        printf("Failed to find DD element\n");
        CkXml_Dispose(xml);
        return;
    }

    //  We need to get the "flattened" DD XML where:
    //    - No whitespace between elements.
    //    - The 5 pre-defined entities are converted.
    //    - The text is encoded in the ISO-8859-1 character set (Latin-1), 
    sbFlattened = CkStringBuilder_Create();
    CkXml_putEmitCompact(ddXml,TRUE);
    CkXml_putEmitXmlDecl(ddXml,FALSE);
    CkXml_GetXmlSb(ddXml,sbFlattened);

    // Compute the SHA-1 message digest of the iso-8859-1 byte representation, 
    // and sign it with our RSA private key, getting the result in base64 format.

    privKey = CkPrivateKey_Create();
    success = CkPrivateKey_LoadAnyFormatFile(privKey,"qa_data/rsa/rsaPrivKey_pkcs8.pem","");
    if (success == FALSE) {
        printf("%s\n",CkPrivateKey_lastErrorText(privKey));
        CkXml_Dispose(xml);
        CkStringBuilder_Dispose(sbFlattened);
        CkPrivateKey_Dispose(privKey);
        return;
    }

    rsa = CkRsa_Create();
    CkRsa_ImportPrivateKeyObj(rsa,privKey);

    CkRsa_putEncodingMode(rsa,"base64");
    CkRsa_putCharset(rsa,"iso-8859-1");
    sig = CkRsa_signStringENC(rsa,CkStringBuilder_getAsString(sbFlattened),"sha1");

    // Add the FRMT signature element to the XML.
    CkXml_UpdateChildContent(xml,"Documento|TED|FRMT",sig);
    CkXml_UpdateAttrAt(xml,"Documento|TED|FRMT",TRUE,"algoritmo","SHA1withRSA");

    CkXml_Dispose(ddXml);

    // See what we have:
    CkXml_putEmitCompact(xml,FALSE);
    CkXml_putEmitXmlDecl(xml,TRUE);
    printf("%s\n",CkXml_getXml(xml));


    CkXml_Dispose(xml);
    CkStringBuilder_Dispose(sbFlattened);
    CkPrivateKey_Dispose(privKey);
    CkRsa_Dispose(rsa);

    }