(Classic ASP) Get a Certificate's Key Size

Demonstrates how to get the RSA key size of a certificate (for example, 1024-bit, 2048-bit, etc.)

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

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

' For this example, I have a certificate in raw base64 format (not PEM),
' that looks like this:  "MIIGkDCCBHigAwIBAgIUMDA ... s/iqLsLA=="
set sbCertBase64 = Server.CreateObject("Chilkat.StringBuilder")
success = sbCertBase64.LoadFile("qa_data/certs/base64Cert.txt","utf-8")

set cert = Server.CreateObject("Chilkat.Cert")
success = cert.LoadFromBase64(sbCertBase64.GetAsString())
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( cert.LastErrorText) & "</pre>"
    Response.End
End If

' Get the public key.
set pubKey = Server.CreateObject("Chilkat.PublicKey")
success = cert.GetPublicKey(pubKey)

numBits = pubKey.KeySize
Response.Write "<pre>" & Server.HTMLEncode( "Number of bits = " & numBits) & "</pre>"

' If using an older version of Chilkat, the key size can be obtained like this:
set xml = Server.CreateObject("Chilkat.Xml")
success = xml.LoadXml(pubKey.GetXml())

set binDat = Server.CreateObject("Chilkat.BinData")
success = binDat.AppendEncoded(xml.GetChildContent("Modulus"),"base64")

numBits = 8 * binDat.NumBytes
Response.Write "<pre>" & Server.HTMLEncode( "Number of bits = " & numBits) & "</pre>"

%>
</body>
</html>