VB.NET

RSA Sign an Encoded Hash

See more RSA Examples

Demonstrates signing a hash (e.g., SHA256) provided as an encoded string (e.g., base64 or hex). VB.NET

Dim success As Boolean = False

' Assuming the smartcard/USB token is installed with the correct drivers from the manufacturer,
' this code can work on multiple platforms including Windows, MacOS, Linux, and iOS.

' Chilkat automatically detects and determines the way in which the HSM is used,
' which can be by PKCS11, Apple Keychain, Microsoft CNG / Crypto API, or ScMinidriver.

Dim cert As New Chilkat.Cert

' Set the token/smartcard PIN prior to loading.
cert.SmartCardPin = "123456"

' Specify the certificate by its common name.
success = cert.LoadFromSmartcard("cn=chilkat-rsa-2048")
If (success = False) Then
    Debug.WriteLine(cert.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("Signing with the private key for this cert: " & cert.SubjectCN)

' Create data to be hashed and signed.
Dim bd As New Chilkat.BinData
Dim i As Integer
For i = 0 To 100
    bd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex")
Next

Dim rsa As New Chilkat.Rsa

' Use the certificate's private key for signing.
success = rsa.SetX509Cert(cert,True)
If (success = False) Then
    Debug.WriteLine(rsa.LastErrorText)
    Exit Sub
End If


' We'll first compute the hash and then pass the encoded hash to be signed.
Dim sha256_base64 As String = bd.GetHash("sha256","base64")
Debug.WriteLine("sha256 hash in base64 format: " & sha256_base64)

' Pass in the base64 hash and return a base64 signature.
rsa.EncodingMode = "base64"
Dim rsaSig_base64 As String = rsa.SignHashENC(sha256_base64,"sha256")
If (success = False) Then
    Debug.WriteLine(rsa.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("RSA signature as base64: " & rsaSig_base64)