Classic ASP Requires Chilkat v11.0.0+
RSASSA-PSS Sign String to Create Base64 PCKS7 Signature

Signs a string to create a PKCS7 signature in the base64 encoding. The signature algorithm is RSASSA-PSS with SHA256.
Chilkat Classic ASP Downloads

Classic ASP
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

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

set crypt = Server.CreateObject("Chilkat.Crypt2")

'  Get a digital certificate with private key from a .pfx
'  (Chilkat has many different ways to provide a cert + private key for siging.
'  Using a PFX is just one possible option.)
set pfx = Server.CreateObject("Chilkat.Pfx")
success = pfx.LoadPfxFile("qa_data/rsassa-pss/privatekey.pfx","PFX_PASSWORD")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( pfx.LastErrorText) & "</pre>"
    Response.End
End If

'  Get the certificate to be used for signing.
'  (The typical case for a PFX is that it contains a cert with an associated private key,
'  as well as other certificates in the chain of authentication.  The cert with the private
'  key should be in the first position at index 0.)

set cert = Server.CreateObject("Chilkat.Cert")
success = pfx.CertAt(0,cert)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( pfx.LastErrorText) & "</pre>"
    Response.End
End If

success = crypt.SetSigningCert(cert)

'  Indicate that RSASSA-PSS with SHA256 should be used.
crypt.SigningAlg = "pss"
crypt.HashAlgorithm = "sha256"

crypt.EncodingMode = "base64"

'  Sign a string and return the base64 PKCS7 detached signature
originalText = "This is a test"
pkcs7sig = crypt.SignStringENC(originalText)
Response.Write "<pre>" & Server.HTMLEncode( "Detached Signature:") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( pkcs7sig) & "</pre>"

'  This signature looks like this:
'  MIIG5wYJKoZIhvcNAQcCoIIG2DCCBtQCAQExDzANBgl .. YToLqEwTdU87ox5g7rvw==

'  The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
'  then copy-and-paste the Base64 signature into the form and decode..

'  The signature can be verified against the original data like this:
success = crypt.VerifyStringENC(originalText,pkcs7sig)
Response.Write "<pre>" & Server.HTMLEncode( "Signature verified: " & success) & "</pre>"
success = crypt.VerifyStringENC("Not the original text",pkcs7sig)
Response.Write "<pre>" & Server.HTMLEncode( "Signature verified: " & success) & "</pre>"

'  Now we'll create an opaque signature (the opposite of a detached signature). 
'  An opaque signature is a PKCS7 message that contains both the original data and
'  the signature.  The verification process extracts the original data.
opaqueSig = crypt.OpaqueSignStringENC(originalText)
Response.Write "<pre>" & Server.HTMLEncode( "Opaque Signature:") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( opaqueSig) & "</pre>"

'  The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
'  then copy-and-paste the Base64 signature into the form and decode..

'  We can verify and extract the original data:
origTxt = crypt.OpaqueVerifyStringENC(opaqueSig)
If (crypt.LastMethodSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( "Signature verification failed.") & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( crypt.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "Signature verified.") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "Extracted text:" & origTxt) & "</pre>"

%>
</body>
</html>