(VB.NET) RSA Sign with PKCS8 Encrypted Key

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it).

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

Dim pkey As New Chilkat.PrivateKey

' Load the private key from an RSA PEM file:
Dim success As Boolean = pkey.LoadPkcs8EncryptedFile("raul_privateKey.key","a0123456789")

Dim pkeyXml As String
' Get the private key in XML format:
pkeyXml = pkey.GetXml()

Dim rsa As New Chilkat.Rsa

' Import the private key into the RSA component:
success = rsa.ImportPrivateKey(pkeyXml)
If (success <> True) Then
    Debug.WriteLine(rsa.LastErrorText)
    Exit Sub
End If


' This example will sign a string, and receive the signature
' in a hex-encoded string.  Therefore, set the encoding mode
' to "hex":
rsa.EncodingMode = "hex"

Dim strData As String = "This is the string to be signed."

' Sign the string using the sha-1 hash algorithm.
' Other valid choices are "md2" and "md5".
Dim hexSig As String = rsa.SignStringENC(strData,"sha-1")

Debug.WriteLine(hexSig)

' Now verify with the public key.
' This example shows how to use the public key from 
' a digital certificate (.cer file)
Dim cert As New Chilkat.Cert
success = cert.LoadFromFile("raul_publicKey.cer")
If (success <> True) Then
    Debug.WriteLine(cert.LastErrorText)
    Exit Sub
End If


Dim pubKey As Chilkat.PublicKey
pubKey = cert.ExportPublicKey()

Dim pubKeyXml As String
' Get the private key in XML format:
pubKeyXml = pubKey.GetXml()

Dim rsa2 As New Chilkat.Rsa
success = rsa2.ImportPublicKey(pubKeyXml)
If (success <> True) Then
    Debug.WriteLine(rsa2.LastErrorText)
    Exit Sub
End If


' Verify the signature against the original data:
rsa2.EncodingMode = "hex"
success = rsa2.VerifyStringENC(strData,"sha-1",hexSig)
If (success <> True) Then
    Debug.WriteLine(rsa2.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("Signature verified!")

' Verify with incorrect data:
success = rsa2.VerifyStringENC("something else","sha-1",hexSig)
If (success <> True) Then
    Debug.WriteLine("Signature not verified! (which was expected in this case)")
Else
    Debug.WriteLine("Hmmm... that's not right...")
End If