VBScript

Verify an RSA Signature Against the Signed String

See more Apple Keychain Examples

Demonstrates how to validate an RSA Signature against the string that was signed. VBScript

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

success = 0

' Create the same string we previously signed in this example: 
' RSA Sign utf-8 Bytes of String to get Base64 RSA Signature

set sb = CreateObject("Chilkat.StringBuilder")
crlfLineEnding = 1

For i = 0 To 10
    success = sb.AppendLine("This is a test.",crlfLineEnding)
Next

base64_rsa_sig = "gWgpEXQqvXN6wh0MuFXPiw2xCb8cnmdizBT1TD1Tpm2GlJ8gnD59DGSj35GGXk1tM+mCOvMa2uW/9gmz8p6A90JLbn918i/2wKGvcde4wXnzPO7JADSNn2UwYzf3rp4/q/JrHv1GZETRJhABSFqTxOgdmdbEJQE/zijOSctCtQAM2CTb6t2BO8uHKSSUAwPH2cbeWxqsaVRLT4ruk5nZOxhoLgLMSjupiSzbE8zSTkkFOEHD+Mbb2xwg85AI0E4DsUnp+hLwwtS0blesgSyvtBY8oJODJeFcJsR7JDOTPdzHQHgJRl/2A4ij5xT91TpXy7ok43jhT6O9j7Q3qrafIQ=="

' Get the public key to be used for signature verification.
set pubKey = CreateObject("Chilkat.PublicKey")
success = pubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
If (success = 0) Then
    outFile.WriteLine(pubKey.LastErrorText)
    WScript.Quit
End If

set rsa = CreateObject("Chilkat.Rsa")
success = rsa.UsePublicKey(pubKey)
If (success = 0) Then
    outFile.WriteLine(rsa.LastErrorText)
    WScript.Quit
End If

' Verify the string against the signature.
' We signed the utf-8 byte representation of the string, so we must indicate
' to also validate against the utf-8 byte representation.
rsa.Charset = "utf-8"
rsa.EncodingMode = "base64"
signedString = sb.GetAsString()
success = rsa.VerifyStringENC(signedString,"sha256",base64_rsa_sig)

If (success = 0) Then
    outFile.WriteLine(rsa.LastErrorText)
    outFile.WriteLine("Signature invalid.")
Else
    outFile.WriteLine("Signature valid.")
End If


outFile.Close