(Visual Basic 6.0) Generate RSA Key and Sign a String

See more RSA Examples

Demonstrates how to generate a new RSA public/private key pair and use it to generate a signature for a string. The (binary) digital signature is returned as a hexidecimalized string.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

Dim rsa As New ChilkatRsa

' Generate a 2048-bit RSA key.
Dim success As Long
success = rsa.GenerateKey(2048)

' To return the signature in hex.
rsa.EncodingMode = "hex"

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

' Sign the SHA256 hash of the string.
Dim hexSig As String
hexSig = rsa.SignStringENC(strData,"sha256")

Debug.Print hexSig
Debug.Print rsa.LastErrorText

' Now verify the signature:
success = rsa.VerifyStringENC(strData,"sha256",hexSig)
If (success = 1) Then
    Debug.Print "Signature verified!"
Else
    Debug.Print rsa.LastErrorText
End If

' Try it with an invalid signature:
success = rsa.VerifyStringENC(strData,"sha256","not a valid sig")
If (success = 1) Then
    Debug.Print "Signature verified!"
Else
    Debug.Print rsa.LastErrorText
End If

' Try it with invalid data:
success = rsa.VerifyStringENC("Not the original data","sha256",hexSig)
If (success = 1) Then
    Debug.Print "Signature verified!"
Else
    Debug.Print rsa.LastErrorText
End If

' Try it with the wrong hash algorithm:
success = rsa.VerifyStringENC(strData,"sha-1",hexSig)
If (success = 1) Then
    Debug.Print "Signature verified!"
Else
    Debug.Print rsa.LastErrorText
End If