(C++) Create JPK VAT metadata XML

Demonstrates how to create the JPK VAT metadata XML (InitUpload) that will be signed using XADES.

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#include <CkXml.h>
#include <CkBinData.h>
#include <CkCrypt2.h>
#include <CkZip.h>
#include <CkZipEntry.h>
#include <CkPrng.h>
#include <CkCert.h>
#include <CkPublicKey.h>
#include <CkRsa.h>

void ChilkatSample(void)
    {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // First build an InitUpload XML template

    // Use this online tool to generate the code from the sample XML below: 
    // Generate Code to Create XML

    // <InitUpload xmlns="http://e-dokumenty.mf.gov.pl">
    //     <DocumentType>JPK</DocumentType>
    //     <Version>01.02.01.20160617</Version>
    //     <EncryptionKey algorithm="RSA" encoding="Base64" mode="ECB" padding="PKCS#1">F9EhKFec...uWqAWUIg==</EncryptionKey>
    //     <DocumentList>
    //         <Document>
    //             <FormCode schemaVersion="1-1" systemCode="JPK_VAT (3)">JPK_VAT</FormCode>
    //             <FileName>JPK_VAT_3_v1-1_20181201.xml</FileName>
    //             <ContentLength>8736</ContentLength>
    //             <HashValue algorithm="SHA-256" encoding="Base64">JFDI1pItwh6dj/Xe1uts/x61qnjZ4DLHpkZMhmf1oKQ=</HashValue>
    //             <FileSignatureList filesNumber="1">
    //                 <Packaging>
    //                     <SplitZip mode="zip" type="split"/>
    //                 </Packaging>
    //                 <Encryption>
    //                     <AES block="16" mode="CBC" padding="PKCS#7" size="256">
    //                         <IV bytes="16" encoding="Base64">z64oN9zXHt1+S3XACRSCYw==</IV>
    //                     </AES>
    //                 </Encryption>
    //                 <FileSignature>
    //                     <OrdinalNumber>1</OrdinalNumber>
    //                     <FileName>JPK_VAT_3_v1-1_20181201-000.xml.zip.aes</FileName>
    //                     <ContentLength>16</ContentLength>
    //                     <HashValue algorithm="MD5" encoding="Base64">5NX0q1935fvMjLFV7E1yDw==</HashValue>
    //                 </FileSignature>
    //             </FileSignatureList>
    //         </Document>
    //     </DocumentList>
    // </InitUpload>

    bool success;
    CkXml xml;
    xml.put_Tag("InitUpload");
    xml.AddAttribute("xmlns","http://e-dokumenty.mf.gov.pl");
    xml.UpdateChildContent("DocumentType","JPK");
    xml.UpdateChildContent("Version","01.02.01.20160617");
    xml.UpdateAttrAt("EncryptionKey",true,"algorithm","RSA");
    xml.UpdateAttrAt("EncryptionKey",true,"encoding","Base64");
    xml.UpdateAttrAt("EncryptionKey",true,"mode","ECB");
    xml.UpdateAttrAt("EncryptionKey",true,"padding","PKCS#1");
    xml.UpdateChildContent("EncryptionKey","TO BE DETERMINED");
    xml.UpdateAttrAt("DocumentList|Document|FormCode",true,"schemaVersion","1-1");
    xml.UpdateAttrAt("DocumentList|Document|FormCode",true,"systemCode","JPK_VAT (3)");
    xml.UpdateChildContent("DocumentList|Document|FormCode","JPK_VAT");
    xml.UpdateChildContent("DocumentList|Document|FileName","JPK_VAT_3_v1-1_20181201.xml");
    xml.UpdateChildContent("DocumentList|Document|ContentLength","9999");
    xml.UpdateAttrAt("DocumentList|Document|HashValue",true,"algorithm","SHA-256");
    xml.UpdateAttrAt("DocumentList|Document|HashValue",true,"encoding","Base64");
    xml.UpdateChildContent("DocumentList|Document|HashValue","TO BE DETERMINED");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList",true,"filesNumber","1");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|Packaging|SplitZip",true,"mode","zip");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|Packaging|SplitZip",true,"type","split");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|Encryption|AES",true,"block","16");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|Encryption|AES",true,"mode","CBC");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|Encryption|AES",true,"padding","PKCS#7");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|Encryption|AES",true,"size","256");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|Encryption|AES|IV",true,"bytes","16");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|Encryption|AES|IV",true,"encoding","Base64");
    xml.UpdateChildContent("DocumentList|Document|FileSignatureList|Encryption|AES|IV","TO BE DETERMINED");
    xml.UpdateChildContent("DocumentList|Document|FileSignatureList|FileSignature|OrdinalNumber","1");
    xml.UpdateChildContent("DocumentList|Document|FileSignatureList|FileSignature|FileName","JPK_VAT_3_v1-1_20181201-000.xml.zip.aes");
    xml.UpdateChildContent("DocumentList|Document|FileSignatureList|FileSignature|ContentLength","9999");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|FileSignature|HashValue",true,"algorithm","MD5");
    xml.UpdateAttrAt("DocumentList|Document|FileSignatureList|FileSignature|HashValue",true,"encoding","Base64");
    xml.UpdateChildContent("DocumentList|Document|FileSignatureList|FileSignature|HashValue","TO BE DETERMINED");

    // ------------------------------------------------------------
    // Step 1: Load our JPK_VAT XML and update the DocumentList|Document|HashValue
    // and DocumentList|Document|ContentLength
    CkBinData bdXml;
    success = bdXml.LoadFile("qa_data/xml_dsig/jpk_vat/JPK_VAT_3_v1-1_20181201-000.xml");
    if (success != true) {
        std::cout << "Failed to load XML file." << "\r\n";
        return;
    }

    xml.UpdateChildContentInt("DocumentList|Document|ContentLength",bdXml.get_NumBytes());

    CkCrypt2 crypt;
    crypt.put_HashAlgorithm("sha256");
    crypt.put_EncodingMode("base64");
    xml.UpdateChildContent("DocumentList|Document|HashValue",crypt.hashBdENC(bdXml));

    // ------------------------------------------------------------
    // Step 2: Create a Zip archive containing the XML.
    CkZip zip;
    // The filename we pass here doesn't matter because we won't actually be creating a .zip file.
    zip.NewZip("anything.zip");
    CkZipEntry *e = zip.AppendBd("JPK_VAT_3_v1-1_20181201-000.xml",bdXml);
    delete e;
    // Write the .zip file to a BinData object.
    CkBinData bdZip;
    zip.WriteBd(bdZip);

    // ------------------------------------------------------------
    // Step 3: Generate a random 256-bit AES key (32-bytes)
    CkPrng prng;
    CkBinData bdAesKey;
    prng.GenRandomBd(32,bdAesKey);
    const char *ivBytes = prng.genRandom(16,"base64");

    // Store the IV (base64 string) in the XML.
    xml.UpdateChildContent("DocumentList|Document|FileSignatureList|Encryption|AES|IV",ivBytes);

    // ------------------------------------------------------------
    // Step 4: AES encrypt our zip archive (the contents of bdZip)
    crypt.put_CipherMode("cbc");
    crypt.put_KeyLength(256);
    crypt.put_CryptAlgorithm("aes");
    crypt.put_PaddingScheme(0);
    crypt.SetEncodedIV(ivBytes,"base64");
    crypt.SetEncodedKey(bdAesKey.getEncoded("base64"),"base64");
    // AES by definition has a block size of 16.
    crypt.EncryptBd(bdZip);

    // bdZip now contains the AES encrypted data. 
    // Note: This is NOT the same as a zip where the contents are AES encrypted.
    // In that case, we have an unencrypted zip structure with AES encrypted files within.
    // In our case, the entire zip file image is encrypted.

    // Save the bdZip to a file.  This is what will get sent to e-dokumenty.mf.gov.pl
    success = bdZip.WriteFile("qa_output/JPK_VAT_3_v1-1_20181201-000.xml.zip.aes");
    xml.UpdateChildContentInt("DocumentList|Document|FileSignatureList|FileSignature|ContentLength",bdZip.get_NumBytes());

    // ------------------------------------------------------------
    // Step 4: RSA Encrypt the AES key using the public key certificate provided by the Ministry of Finance
    CkCert cert;
    success = cert.LoadFromFile("qa_data/pem/mf_public_rsa.pem");
    if (success != true) {
        std::cout << cert.lastErrorText() << "\r\n";
        return;
    }

    CkPublicKey *pubKey = cert.ExportPublicKey();
    CkRsa rsa;
    rsa.ImportPublicKeyObj(*pubKey);
    delete pubKey;

    rsa.put_EncodingMode("base64");
    rsa.put_LittleEndian(false);
    // in-place RSA encrypt the contents of bdAesKey.
    rsa.EncryptBd(bdAesKey,false);
    xml.UpdateChildContent("EncryptionKey",bdAesKey.getEncoded("base64"));

    // Step 5: We forgot to get the MD5 hash of the AES encrypted zip.
    // (I'm assuming we need the MD5 of the encrypted zip as opposed to the MD5 of the pre-encrypted zip..)
    crypt.put_HashAlgorithm("md5");
    xml.UpdateChildContent("DocumentList|Document|FileSignatureList|FileSignature|HashValue",crypt.hashBdENC(bdZip));

    // At this point, the XML is prepared and the AES encrypted image of the zip file is written
    // to a file (and also in bdZip).
    const char *finalXml = xml.getXml();
    std::cout << finalXml << "\r\n";

    xml.SaveXml("qa_output/jpk_vat.xml");

    std::cout << "Finished." << "\r\n";
    }