(Go) 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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    // 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 := chilkat.NewZip()
    success := zip.OpenZip("qa_data/xml_dsig/offline_paperless_kyc.zip")
    if success == false {
        fmt.Println(zip.LastErrorText())
        zip.DisposeZip()
        return
    }

    // The .zip should contain 1 XML file.
    entry := zip.GetEntryByIndex(0)
    if zip.LastMethodSuccess() == false {
        fmt.Println(zip.LastErrorText())
        zip.DisposeZip()
        return
    }

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

    bdXml := chilkat.NewBinData()
    // The XML file will be unzipped into the bdXml object.
    success = entry.UnzipToBd(bdXml)
    if success == false {
        fmt.Println(entry.LastErrorText())
        entry.DisposeZipEntry()
        zip.DisposeZip()
        bdXml.DisposeBinData()
        return
    }

    entry.DisposeZipEntry()

    // First verify the XML digital signature.
    dsig := chilkat.NewXmlDSig()
    success = dsig.LoadSignatureBd(bdXml)
    if success != true {
        fmt.Println(dsig.LastErrorText())
        zip.DisposeZip()
        bdXml.DisposeBinData()
        dsig.DisposeXmlDSig()
        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 := chilkat.NewCert()
    success = cert.LoadFromFile("qa_data/xml_dsig/uidai_auth_sign_prod_2023.cer")
    if success != true {
        fmt.Println(cert.LastErrorText())
        zip.DisposeZip()
        bdXml.DisposeBinData()
        dsig.DisposeXmlDSig()
        cert.DisposeCert()
        return
    }

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

    // The XML in this example contains only 1 signature.
    bVerifyReferenceDigests := true
    bVerified := dsig.VerifySignature(bVerifyReferenceDigests)
    if bVerified == false {
        fmt.Println(dsig.LastErrorText())
        fmt.Println("The signature was not valid.")
        zip.DisposeZip()
        bdXml.DisposeBinData()
        dsig.DisposeXmlDSig()
        cert.DisposeCert()
        return
    }

    fmt.Println("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 := chilkat.NewCrypt2()
    crypt.SetHashAlgorithm("sha256")
    crypt.SetEncodingMode("hexlower")

    strToHash := "1234567890Lock@487"
    bdHash := chilkat.NewBinData()
    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
    var i int
    for i = 1; i <= numTimesToHash; i++ {
        tmpStr := crypt.HashBdENC(bdHash)
        bdHash.Clear()
        bdHash.AppendString(*tmpStr,"utf-8")
    }

    fmt.Println("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 := chilkat.NewXml()
    success = xml.LoadBd(bdXml,true)
    m_hash := xml.ChilkatPath("UidData|Poi|(m)")

    fmt.Println("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++ {
        tmpStr := crypt.HashBdENC(bdHash)
        bdHash.Clear()
        bdHash.AppendString(*tmpStr,"utf-8")
    }

    fmt.Println("Computed Email hash = ", *bdHash.GetString("utf-8"))

    e_hash := xml.ChilkatPath("UidData|Poi|(e)")
    fmt.Println("Stored Email hash   = ", *e_hash)

    zip.DisposeZip()
    bdXml.DisposeBinData()
    dsig.DisposeXmlDSig()
    cert.DisposeCert()
    crypt.DisposeCrypt2()
    bdHash.DisposeBinData()
    xml.DisposeXml()