(Unicode C++) Aadhaar Paperless Offline e-kyc

Opens an encrypted .zip containing Aadhaar Paperless Offline e-KYC XML. Gets the XML and validates the digital signature. Then computes the hash for the mobile number and Email ID.

For more information, see https://uidai.gov.in/ecosystem/authentication-devices-documents/about-aadhaar-paperless-offline-e-kyc.html

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#include <CkZipW.h>
#include <CkZipEntryW.h>
#include <CkBinDataW.h>
#include <CkXmlDSigW.h>
#include <CkCertW.h>
#include <CkPublicKeyW.h>
#include <CkCrypt2W.h>
#include <CkXmlW.h>

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

    // Open the .zip containing the Aadhaar Paperless Offline e-KYC XML.
    // The .zip is encrypted using the "Share Phrase".
    CkZipW zip;
    bool success = zip.OpenZip(L"qa_data/xml_dsig/offline_paperless_kyc.zip");
    if (success == false) {
        wprintf(L"%s\n",zip.lastErrorText());
        return;
    }

    // The .zip should contain 1 XML file.
    CkZipEntryW *entry = zip.GetEntryByIndex(0);
    if (zip.get_LastMethodSuccess() == false) {
        wprintf(L"%s\n",zip.lastErrorText());
        return;
    }

    // To get the contents, we need to specify the Share Phrase.
    const wchar_t *sharePhrase = L"Lock@487";
    zip.put_DecryptPassword(sharePhrase);

    CkBinDataW bdXml;
    // The XML file will be unzipped into the bdXml object.
    success = entry->UnzipToBd(bdXml);
    if (success == false) {
        wprintf(L"%s\n",entry->lastErrorText());
        delete entry;
        return;
    }

    delete entry;

    // First verify the XML digital signature.
    CkXmlDSigW dsig;
    success = dsig.LoadSignatureBd(bdXml);
    if (success != true) {
        wprintf(L"%s\n",dsig.lastErrorText());
        return;
    }

    // The UIDAI XML signature does not contain the KeyInfo, so we must load the uidai certificate
    // and indicate that its public key is to be used for verifying the signature.
    CkCertW cert;
    success = cert.LoadFromFile(L"qa_data/xml_dsig/uidai_auth_sign_prod_2023.cer");
    if (success != true) {
        wprintf(L"%s\n",cert.lastErrorText());
        return;
    }

    // Get the certificate's public key.
    CkPublicKeyW *pubKey = cert.ExportPublicKey();
    success = dsig.SetPublicKey(*pubKey);
    delete pubKey;

    // The XML in this example contains only 1 signature.
    bool bVerifyReferenceDigests = true;
    bool bVerified = dsig.VerifySignature(bVerifyReferenceDigests);
    if (bVerified == false) {
        wprintf(L"%s\n",dsig.lastErrorText());
        wprintf(L"The signature was not valid.\n");
        return;
    }

    wprintf(L"The XML digital signature is valid.\n");

    // Let's compute the hash for the Mobile Number.

    // 	Hashing logic for Mobile Number :
    // 	Sha256(Sha256(Mobile+SharePhrase))*number of times last digit of Aadhaar number
    // 	(Ref ID field contains last 4 digits).
    // 
    // 	Example :
    // 	Mobile: 1234567890
    // 	Aadhaar Number:XXXX XXXX 3632
    // 	Passcode : Lock@487
    // 	Hash: Sha256(Sha256(1234567890Lock@487))*2
    // 	In case of Aadhaar number ends with Zero we will hashed one time.

    CkCrypt2W crypt;
    crypt.put_HashAlgorithm(L"sha256");
    crypt.put_EncodingMode(L"hexlower");

    const wchar_t *strToHash = L"1234567890Lock@487";
    CkBinDataW bdHash;
    success = bdHash.AppendString(strToHash,L"utf-8");

    // Hash a number of times equal to the last digit of your Aadhaar number.
    // If the Aadhaar number ends with 0, then hash one time.
    // For this example, we'll just set the number of times to hash
    // for the case where an Aadhaar number ends in "9"
    int numTimesToHash = 9;
    int i;
    for (i = 1; i <= numTimesToHash; i++) {
        const wchar_t *tmpStr = crypt.hashBdENC(bdHash);
        bdHash.Clear();
        bdHash.AppendString(tmpStr,L"utf-8");
    }

    wprintf(L"Computed Mobile hash = %s\n",bdHash.getString(L"utf-8"));

    // Let's get the mobile hash stored in the XML and compare it with our computed hash.
    CkXmlW xml;
    success = xml.LoadBd(bdXml,true);
    const wchar_t *m_hash = xml.chilkatPath(L"UidData|Poi|(m)");

    wprintf(L"Stored Mobile hash   = %s\n",m_hash);

    // Now do the same thing for the email hash:

    strToHash = L"abc@gm.comLock@487";
    bdHash.Clear();
    success = bdHash.AppendString(strToHash,L"utf-8");

    for (i = 1; i <= numTimesToHash; i++) {
        const wchar_t *tmpStr = crypt.hashBdENC(bdHash);
        bdHash.Clear();
        bdHash.AppendString(tmpStr,L"utf-8");
    }

    wprintf(L"Computed Email hash = %s\n",bdHash.getString(L"utf-8"));

    const wchar_t *e_hash = xml.chilkatPath(L"UidData|Poi|(e)");
    wprintf(L"Stored Email hash   = %s\n",e_hash);
    }