(Visual Basic 6.0) 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 ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

' 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".
Dim zip As New ChilkatZip
Dim success As Long
success = zip.OpenZip("qa_data/xml_dsig/offline_paperless_kyc.zip")
If (success = 0) Then
    Debug.Print zip.LastErrorText
    Exit Sub
End If

' The .zip should contain 1 XML file.
Dim entry As ChilkatZipEntry
Set entry = zip.GetEntryByIndex(0)
If (zip.LastMethodSuccess = 0) Then
    Debug.Print zip.LastErrorText
    Exit Sub
End If

' To get the contents, we need to specify the Share Phrase.
Dim sharePhrase As String
sharePhrase = "Lock@487"
zip.DecryptPassword = sharePhrase

Dim bdXml As New ChilkatBinData
' The XML file will be unzipped into the bdXml object.
success = entry.UnzipToBd(bdXml)
If (success = 0) Then
    Debug.Print entry.LastErrorText

    Exit Sub
End If

' First verify the XML digital signature.
Dim dsig As New ChilkatXmlDSig
success = dsig.LoadSignatureBd(bdXml)
If (success <> 1) Then
    Debug.Print dsig.LastErrorText
    Exit Sub
End If

' 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.
Dim cert As New ChilkatCert
success = cert.LoadFromFile("qa_data/xml_dsig/uidai_auth_sign_prod_2023.cer")
If (success <> 1) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

' Get the certificate's public key.
Dim pubKey As PublicKey
Set pubKey = cert.ExportPublicKey()
success = dsig.SetPublicKey(pubKey)

' The XML in this example contains only 1 signature.
Dim bVerifyReferenceDigests As Long
bVerifyReferenceDigests = 1
Dim bVerified As Long
bVerified = dsig.VerifySignature(bVerifyReferenceDigests)
If (bVerified = 0) Then
    Debug.Print dsig.LastErrorText
    Debug.Print "The signature was not valid."
    Exit Sub
End If

Debug.Print "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.

Dim crypt As New ChilkatCrypt2
crypt.HashAlgorithm = "sha256"
crypt.EncodingMode = "hexlower"

Dim strToHash As String
strToHash = "1234567890Lock@487"
Dim bdHash As New ChilkatBinData
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"
Dim numTimesToHash As Long
numTimesToHash = 9
Dim i As Long
For i = 1 To numTimesToHash
    Dim tmpStr As String
    tmpStr = crypt.HashBdENC(bdHash)
    success = bdHash.Clear()
    success = bdHash.AppendString(tmpStr,"utf-8")
Next

Debug.Print "Computed Mobile hash = " & bdHash.GetString("utf-8")

' Let's get the mobile hash stored in the XML and compare it with our computed hash.
Dim xml As New ChilkatXml
success = xml.LoadBd(bdXml,1)
Dim m_hash As String
m_hash = xml.ChilkatPath("UidData|Poi|(m)")

Debug.Print "Stored Mobile hash   = " & m_hash

' Now do the same thing for the email hash:

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

For i = 1 To numTimesToHash
    Dim tmpStr As String
    tmpStr = crypt.HashBdENC(bdHash)
    success = bdHash.Clear()
    success = bdHash.AppendString(tmpStr,"utf-8")
Next

Debug.Print "Computed Email hash = " & bdHash.GetString("utf-8")

Dim e_hash As String
e_hash = xml.ChilkatPath("UidData|Poi|(e)")
Debug.Print "Stored Email hash   = " & e_hash