(VB.NET) RSA Sign Binary Data and Verify (Recover the Original Data)

Demonstrates how to RSA sign binary data and then verify/recover the original data.

Note: This example uses methods introduced in Chilkat v9.5.0.77.

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' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' Load an RSA private key for signing.
Dim privKey As New Chilkat.PrivateKey
Dim success As Boolean = privKey.LoadEncryptedPemFile("qa_data/pem/rsa_passwd.pem","passwd")
If (success <> True) Then
    Debug.WriteLine(privKey.LastErrorText)
    Exit Sub
End If


Dim rsa As New Chilkat.Rsa
rsa.ImportPrivateKeyObj(privKey)

' We have some binary data (in hex) to sign
Dim originalData As String = "0102030405060708090A"
Dim bd As New Chilkat.BinData
bd.AppendEncoded(originalData,"hex")

' If successful, the contents of bd are replaced with the RSA signature.
success = rsa.OpenSslSignBd(bd)
If (success <> True) Then
    Debug.WriteLine(rsa.LastErrorText)
    Exit Sub
End If


' Show the RSA signature in base64
Debug.WriteLine(bd.GetEncoded("base64"))


' ------------------------------------------
' Get the public key from the private key
Dim pubKey As Chilkat.PublicKey = privKey.GetPublicKey()

' Verify the signature and extract the original data.
Dim rsa2 As New Chilkat.Rsa
rsa2.ImportPublicKeyObj(pubKey)

Dim bVerified As Boolean = rsa2.OpenSslVerifyBd(bd)
Debug.WriteLine("signature verified: " & bVerified)

' Show the original data:
Debug.WriteLine("original data: " & bd.GetEncoded("hex"))