(Delphi ActiveX) 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

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
zip: TChilkatZip;
success: Integer;
entry: IChilkatZipEntry;
sharePhrase: WideString;
bdXml: TChilkatBinData;
dsig: TChilkatXmlDSig;
cert: TChilkatCert;
pubKey: IPublicKey;
bVerifyReferenceDigests: Integer;
bVerified: Integer;
crypt: TChilkatCrypt2;
strToHash: WideString;
bdHash: TChilkatBinData;
numTimesToHash: Integer;
i: Integer;
tmpStr: WideString;
xml: TChilkatXml;
m_hash: WideString;
tmpStr: WideString;
e_hash: WideString;

begin
// 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 := TChilkatZip.Create(Self);
success := zip.OpenZip('qa_data/xml_dsig/offline_paperless_kyc.zip');
if (success = 0) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// The .zip should contain 1 XML file.
entry := zip.GetEntryByIndex(0);
if (zip.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

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

bdXml := TChilkatBinData.Create(Self);
// The XML file will be unzipped into the bdXml object.
success := entry.UnzipToBd(bdXml.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(entry.LastErrorText);

    Exit;
  end;

// First verify the XML digital signature.
dsig := TChilkatXmlDSig.Create(Self);
success := dsig.LoadSignatureBd(bdXml.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(dsig.LastErrorText);
    Exit;
  end;

// 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 := TChilkatCert.Create(Self);
success := cert.LoadFromFile('qa_data/xml_dsig/uidai_auth_sign_prod_2023.cer');
if (success <> 1) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

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

// The XML in this example contains only 1 signature.
bVerifyReferenceDigests := 1;
bVerified := dsig.VerifySignature(bVerifyReferenceDigests);
if (bVerified = 0) then
  begin
    Memo1.Lines.Add(dsig.LastErrorText);
    Memo1.Lines.Add('The signature was not valid.');
    Exit;
  end;

Memo1.Lines.Add('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.

crypt := TChilkatCrypt2.Create(Self);
crypt.HashAlgorithm := 'sha256';
crypt.EncodingMode := 'hexlower';

strToHash := '1234567890Lock@487';
bdHash := TChilkatBinData.Create(Self);
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"
numTimesToHash := 9;

for i := 1 to numTimesToHash do
  begin
    tmpStr := crypt.HashBdENC(bdHash.ControlInterface);
    bdHash.Clear();
    bdHash.AppendString(tmpStr,'utf-8');
  end;

Memo1.Lines.Add('Computed Mobile hash = ' + bdHash.GetString('utf-8'));

// Let's get the mobile hash stored in the XML and compare it with our computed hash.
xml := TChilkatXml.Create(Self);
success := xml.LoadBd(bdXml.ControlInterface,1);
m_hash := xml.ChilkatPath('UidData|Poi|(m)');

Memo1.Lines.Add('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 to numTimesToHash do
  begin
    tmpStr := crypt.HashBdENC(bdHash.ControlInterface);
    bdHash.Clear();
    bdHash.AppendString(tmpStr,'utf-8');
  end;

Memo1.Lines.Add('Computed Email hash = ' + bdHash.GetString('utf-8'));

e_hash := xml.ChilkatPath('UidData|Poi|(e)');
Memo1.Lines.Add('Stored Email hash   = ' + e_hash);
end;