(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 <C_CkZipW.h>
#include <C_CkZipEntryW.h>
#include <C_CkBinDataW.h>
#include <C_CkXmlDSigW.h>
#include <C_CkCertW.h>
#include <C_CkPublicKeyW.h>
#include <C_CkCrypt2W.h>
#include <C_CkXmlW.h>

void ChilkatSample(void)
    {
    HCkZipW zip;
    BOOL success;
    HCkZipEntryW entry;
    const wchar_t *sharePhrase;
    HCkBinDataW bdXml;
    HCkXmlDSigW dsig;
    HCkCertW cert;
    HCkPublicKeyW pubKey;
    BOOL bVerifyReferenceDigests;
    BOOL bVerified;
    HCkCrypt2W crypt;
    const wchar_t *strToHash;
    HCkBinDataW bdHash;
    int numTimesToHash;
    int i;
    const wchar_t *tmpStr;
    HCkXmlW xml;
    const wchar_t *m_hash;
    const wchar_t *tmpStr;
    const wchar_t *e_hash;

    // 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".
    zip = CkZipW_Create();
    success = CkZipW_OpenZip(zip,L"qa_data/xml_dsig/offline_paperless_kyc.zip");
    if (success == FALSE) {
        wprintf(L"%s\n",CkZipW_lastErrorText(zip));
        CkZipW_Dispose(zip);
        return;
    }

    // The .zip should contain 1 XML file.
    entry = CkZipW_GetEntryByIndex(zip,0);
    if (CkZipW_getLastMethodSuccess(zip) == FALSE) {
        wprintf(L"%s\n",CkZipW_lastErrorText(zip));
        CkZipW_Dispose(zip);
        return;
    }

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

    bdXml = CkBinDataW_Create();
    // The XML file will be unzipped into the bdXml object.
    success = CkZipEntryW_UnzipToBd(entry,bdXml);
    if (success == FALSE) {
        wprintf(L"%s\n",CkZipEntryW_lastErrorText(entry));
        CkZipEntryW_Dispose(entry);
        CkZipW_Dispose(zip);
        CkBinDataW_Dispose(bdXml);
        return;
    }

    CkZipEntryW_Dispose(entry);

    // First verify the XML digital signature.
    dsig = CkXmlDSigW_Create();
    success = CkXmlDSigW_LoadSignatureBd(dsig,bdXml);
    if (success != TRUE) {
        wprintf(L"%s\n",CkXmlDSigW_lastErrorText(dsig));
        CkZipW_Dispose(zip);
        CkBinDataW_Dispose(bdXml);
        CkXmlDSigW_Dispose(dsig);
        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.
    cert = CkCertW_Create();
    success = CkCertW_LoadFromFile(cert,L"qa_data/xml_dsig/uidai_auth_sign_prod_2023.cer");
    if (success != TRUE) {
        wprintf(L"%s\n",CkCertW_lastErrorText(cert));
        CkZipW_Dispose(zip);
        CkBinDataW_Dispose(bdXml);
        CkXmlDSigW_Dispose(dsig);
        CkCertW_Dispose(cert);
        return;
    }

    // Get the certificate's public key.
    pubKey = CkCertW_ExportPublicKey(cert);
    success = CkXmlDSigW_SetPublicKey(dsig,pubKey);
    CkPublicKeyW_Dispose(pubKey);

    // The XML in this example contains only 1 signature.
    bVerifyReferenceDigests = TRUE;
    bVerified = CkXmlDSigW_VerifySignature(dsig,bVerifyReferenceDigests);
    if (bVerified == FALSE) {
        wprintf(L"%s\n",CkXmlDSigW_lastErrorText(dsig));
        wprintf(L"The signature was not valid.\n");
        CkZipW_Dispose(zip);
        CkBinDataW_Dispose(bdXml);
        CkXmlDSigW_Dispose(dsig);
        CkCertW_Dispose(cert);
        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.

    crypt = CkCrypt2W_Create();
    CkCrypt2W_putHashAlgorithm(crypt,L"sha256");
    CkCrypt2W_putEncodingMode(crypt,L"hexlower");

    strToHash = L"1234567890Lock@487";
    bdHash = CkBinDataW_Create();
    success = CkBinDataW_AppendString(bdHash,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"
    numTimesToHash = 9;

    for (i = 1; i <= numTimesToHash; i++) {
        tmpStr = CkCrypt2W_hashBdENC(crypt,bdHash);
        CkBinDataW_Clear(bdHash);
        CkBinDataW_AppendString(bdHash,tmpStr,L"utf-8");
    }

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

    // Let's get the mobile hash stored in the XML and compare it with our computed hash.
    xml = CkXmlW_Create();
    success = CkXmlW_LoadBd(xml,bdXml,TRUE);
    m_hash = CkXmlW_chilkatPath(xml,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";
    CkBinDataW_Clear(bdHash);
    success = CkBinDataW_AppendString(bdHash,strToHash,L"utf-8");

    for (i = 1; i <= numTimesToHash; i++) {
        tmpStr = CkCrypt2W_hashBdENC(crypt,bdHash);
        CkBinDataW_Clear(bdHash);
        CkBinDataW_AppendString(bdHash,tmpStr,L"utf-8");
    }

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

    e_hash = CkXmlW_chilkatPath(xml,L"UidData|Poi|(e)");
    wprintf(L"Stored Email hash   = %s\n",e_hash);


    CkZipW_Dispose(zip);
    CkBinDataW_Dispose(bdXml);
    CkXmlDSigW_Dispose(dsig);
    CkCertW_Dispose(cert);
    CkCrypt2W_Dispose(crypt);
    CkBinDataW_Dispose(bdHash);
    CkXmlW_Dispose(xml);

    }