(Node.js) 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

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // 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".
    var zip = new chilkat.Zip();
    var success = zip.OpenZip("qa_data/xml_dsig/offline_paperless_kyc.zip");
    if (success == false) {
        console.log(zip.LastErrorText);
        return;
    }

    // The .zip should contain 1 XML file.
    // entry: ZipEntry
    var entry = zip.GetEntryByIndex(0);
    if (zip.LastMethodSuccess == false) {
        console.log(zip.LastErrorText);
        return;
    }

    // To get the contents, we need to specify the Share Phrase.
    var sharePhrase = "Lock@487";
    zip.DecryptPassword = sharePhrase;

    var bdXml = new chilkat.BinData();
    // The XML file will be unzipped into the bdXml object.
    success = entry.UnzipToBd(bdXml);
    if (success == false) {
        console.log(entry.LastErrorText);

        return;
    }

    // First verify the XML digital signature.
    var dsig = new chilkat.XmlDSig();
    success = dsig.LoadSignatureBd(bdXml);
    if (success !== true) {
        console.log(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.
    var cert = new chilkat.Cert();
    success = cert.LoadFromFile("qa_data/xml_dsig/uidai_auth_sign_prod_2023.cer");
    if (success !== true) {
        console.log(cert.LastErrorText);
        return;
    }

    // Get the certificate's public key.
    // pubKey: PublicKey
    var pubKey = cert.ExportPublicKey();
    success = dsig.SetPublicKey(pubKey);

    // The XML in this example contains only 1 signature.
    var bVerifyReferenceDigests = true;
    var bVerified = dsig.VerifySignature(bVerifyReferenceDigests);
    if (bVerified == false) {
        console.log(dsig.LastErrorText);
        console.log("The signature was not valid.");
        return;
    }

    console.log("The XML digital signature is valid.");

    // 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.

    var crypt = new chilkat.Crypt2();
    crypt.HashAlgorithm = "sha256";
    crypt.EncodingMode = "hexlower";

    var strToHash = "1234567890Lock@487";
    var bdHash = new chilkat.BinData();
    success = bdHash.AppendString(strToHash,"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"
    var numTimesToHash = 9;
    var i;
    for (i = 1; i <= numTimesToHash; i++) {
        var tmpStr = crypt.HashBdENC(bdHash);
        bdHash.Clear();
        bdHash.AppendString(tmpStr,"utf-8");
    }

    console.log("Computed Mobile hash = " + bdHash.GetString("utf-8"));

    // Let's get the mobile hash stored in the XML and compare it with our computed hash.
    var xml = new chilkat.Xml();
    success = xml.LoadBd(bdXml,true);
    var m_hash = xml.ChilkatPath("UidData|Poi|(m)");

    console.log("Stored Mobile hash   = " + m_hash);

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

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

    for (i = 1; i <= numTimesToHash; i++) {
        var tmpStr = crypt.HashBdENC(bdHash);
        bdHash.Clear();
        bdHash.AppendString(tmpStr,"utf-8");
    }

    console.log("Computed Email hash = " + bdHash.GetString("utf-8"));

    var e_hash = xml.ChilkatPath("UidData|Poi|(e)");
    console.log("Stored Email hash   = " + e_hash);

}

chilkatExample();