(Xojo Plugin) 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 Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

// 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 Chilkat.Zip
Dim success As Boolean
success = zip.OpenZip("qa_data/xml_dsig/offline_paperless_kyc.zip")
If (success = False) Then
    System.DebugLog(zip.LastErrorText)
    Return
End If

// The .zip should contain 1 XML file.
Dim entry As Chilkat.ZipEntry
entry = zip.GetEntryByIndex(0)
If (zip.LastMethodSuccess = False) Then
    System.DebugLog(zip.LastErrorText)
    Return
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 Chilkat.BinData
// The XML file will be unzipped into the bdXml object.
success = entry.UnzipToBd(bdXml)
If (success = False) Then
    System.DebugLog(entry.LastErrorText)

    Return
End If

// First verify the XML digital signature.
Dim dsig As New Chilkat.XmlDSig
success = dsig.LoadSignatureBd(bdXml)
If (success <> True) Then
    System.DebugLog(dsig.LastErrorText)
    Return
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 Chilkat.Cert
success = cert.LoadFromFile("qa_data/xml_dsig/uidai_auth_sign_prod_2023.cer")
If (success <> True) Then
    System.DebugLog(cert.LastErrorText)
    Return
End If

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

// The XML in this example contains only 1 signature.
Dim bVerifyReferenceDigests As Boolean
bVerifyReferenceDigests = True
Dim bVerified As Boolean
bVerified = dsig.VerifySignature(bVerifyReferenceDigests)
If (bVerified = False) Then
    System.DebugLog(dsig.LastErrorText)
    System.DebugLog("The signature was not valid.")
    Return
End If

System.DebugLog("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 Chilkat.Crypt2
crypt.HashAlgorithm = "sha256"
crypt.EncodingMode = "hexlower"

Dim strToHash As String
strToHash = "1234567890Lock@487"
Dim bdHash As 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"
Dim numTimesToHash As Int32
numTimesToHash = 9
Dim i As Int32
For i = 1 To numTimesToHash
    Dim tmpStr As String
    tmpStr = crypt.HashBdENC(bdHash)
    success = bdHash.Clear()
    success = bdHash.AppendString(tmpStr,"utf-8")
Next

System.DebugLog("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 Chilkat.Xml
success = xml.LoadBd(bdXml,True)
Dim m_hash As String
m_hash = xml.ChilkatPath("UidData|Poi|(m)")

System.DebugLog("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

System.DebugLog("Computed Email hash = " + bdHash.GetString("utf-8"))

Dim e_hash As String
e_hash = xml.ChilkatPath("UidData|Poi|(e)")
System.DebugLog("Stored Email hash   = " + e_hash)