(VBScript) Decrypt a SAML Response

Demonstrates how to decrypt a SAML response.

Note: This example requires Chilkat v9.5.0.76 or greater.

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

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

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

' This example decrypts this SAML response:

' <?xml version="1.0" encoding="UTF-8" ?>
' <saml2p:Response Destination="https://deskflow-asp2.com/ubc/ubcdfe.dll/cwlacs" ID="_e4585eaeedbcaf7c24dff7f1ee2499f5" IssueInstant="2018-10-11T17:46:20.727Z" Version="2.0" xmlns:saml2p="urn:oasis:names:tc:SAML:2.0:protocol">
'     <saml2:Issuer xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion">https://authentication.stg.id.ubc.ca</saml2:Issuer>
'     <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
'         <ds:SignedInfo>
'             <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
'             <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
'             <ds:Reference URI="#_e4585eaeedbcaf7c24dff7f1ee2499f5">
'                 <ds:Transforms>
'                     <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
'                     <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
'                 </ds:Transforms>
'                 <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
'                 <ds:DigestValue>1ui22tqFyYEOoWI19CMwz4n+ynxNjLDGdTeRMdi60EU=</ds:DigestValue>
'             </ds:Reference>
'         </ds:SignedInfo>
'         <ds:SignatureValue>ROg7FXV6vsp8socVhdo76/i7cRHGGKIveAiScKdujZT0QrHVqIvvbZ/RnwvEMJ9H9i/kJFAQA171
' 		Eo2kDjSdvNFQ/YcKaJUwMtAwT05yVatGV42RZKEf7ME+vpcCTR1LWZdrhat1FWCg1MNQwNWB0EL5
' 		fEP2a4jAcSTB8tFbjTAHsv7IWC39E5RVv99mACYXLa7iGZLtORANZxgYu5qQgmH6pUkI6Z1cpmf+
' 		m9mIjKM6LF0EvLfWOBWL6udZ+GsHPOLjVTJg+1S0xb9FQCYDVW1QhbjSS0icKHKTNNbrsaxllVDY
' 		m4q27YQjRh+XxugPgvsZ61Pxlto8Jbg+6jUlMQ==</ds:SignatureValue>
'         <ds:KeyInfo>
'             <ds:X509Data>
'                 <ds:X509Certificate>MIIDTTCCAjWgAwIBAgIVAJccYyIV6wly8XyddumpgnHMJ2JLMA0GCSqGSIb3DQEBCwUAMCcxJTAj
' 			BgNVBAMMHGF1dGhlbnRpY2F0aW9uLnN0Zy5pZC51YmMuY2EwHhcNMTcwMzAxMTk1NDM0WhcNMzcw
' 			...
' 			xUuh6HuHKIwQqHBz7udxbH3Zbb6jXGDJjiDHt1LRJ8xbVisFIcDlIwsGQQi0HeEJfx4P</ds:X509Certificate>
'             </ds:X509Data>
'         </ds:KeyInfo>
'     </ds:Signature>
'     <saml2p:Status>
'         <saml2p:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
'     </saml2p:Status>
'     <saml2:EncryptedAssertion xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion">
'         <xenc:EncryptedData Id="_314d80b9cf02d8eda8d686a6ffd626cf" Type="http://www.w3.org/2001/04/xmlenc#Element" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
'             <xenc:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#aes128-cbc" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"/>
'             <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
'                 <xenc:EncryptedKey Id="_d7b6da6fb59a627ebb4a96928441ab79" Recipient="https://ubcdfe.deskflow-asp2.com" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
'                     <xenc:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
'                         <ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" xmlns:ds="http://www.w3.org/2000/09/xmldsig#"/>
'                     </xenc:EncryptionMethod>
'                     <ds:KeyInfo>
'                         <ds:X509Data>
'                             <ds:X509Certificate>MIICuzCCAiQCCQD3bpigRnKMSzANBgkqhkiG9w0BAQsFADCBoTELMAkGA1UEBhMCQ0ExEDAOBgNV
' 				BAgMB09udGFyaW8xEDAOBgNVBAcMB1Rvcm9udG8xJjAkBgNVBAoMHVRhY3RpY2FsIEJ1c2luZXNz
' 				...
' 				kVRcHd1UK3q7G8FoykWjdQz/0EoMTfEZ+Md56mLOe48eMUZV2ONZuL1kDCEKw1UwkaDQI4Pf8pzx
' 				82b9rgw9wBDtvu5eFPlUGEGIBw==</ds:X509Certificate>
'                         </ds:X509Data>
'                     </ds:KeyInfo>
'                     <xenc:CipherData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
'                         <xenc:CipherValue>BNHfUOpgdPE5BgpN2VIZIDthMAv1rxk91qVnWyCZOG9bmUKChJtTUqMpndot7VJwYuyKFshkAdnT
' 				D79KGdlSA1xHKcVeZXXzDWglqSyYjzhDCsyOhPaI4HelMFgCLwyFz89uEpUpqlvfl8ol3Am/XnzQ
' 				Vp7V7oS76hocjUI51Qs=</xenc:CipherValue>
'                     </xenc:CipherData>
'                 </xenc:EncryptedKey>
'             </ds:KeyInfo>
'             <xenc:CipherData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
'                 <xenc:CipherValue>R6l7tmbnXrOfBgB8lA3KnwLYsLH5ZO5omQ7Hp5K05atzw2o55xmCXVMYhNneFxMtxUh6raEyHeZX
' 			PTZNgWrvdqc4GYND/R7MhRrJzk9OAq1WyoOXwbtRpwNDwWA4N2IuprPQJbvjVxaw/PesZMZwZqlp
' 			...
' 			zm9zAxahyu8Ooe8M4r3HN2cY0JxxxkZtDiulbnyA+rRtXfBRJtangvFQ4iFAnzM/Yg9hMyW9jcu0
' 			S7FzuRB9ONMxi+nh0IFWgqp+</xenc:CipherValue>
'             </xenc:CipherData>
'         </xenc:EncryptedData>
'     </saml2:EncryptedAssertion>
' </saml2p:Response>

' The sample encrypted SAML response and RSA private key are available online:
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Http")
set http = CreateObject("Chilkat.Http")
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbSamlResponse = CreateObject("Chilkat.StringBuilder")
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbPrivateKeyPem = CreateObject("Chilkat.StringBuilder")
success = http.QuickGetSb("https://chilkatdownload.com/data/samlresponse.xml",sbSamlResponse)
If (success = 1) Then
    success = http.QuickGetSb("https://chilkatdownload.com/data/samlresponse_privkey.pem",sbPrivateKeyPem)
End If

If (success <> 1) Then
    outFile.WriteLine(http.LastErrorText)
    WScript.Quit
End If

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Xml")
set xml = CreateObject("Chilkat.Xml")
success = xml.LoadSb(sbSamlResponse,1)

' Load the RSA private key..
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PrivateKey")
set privkey = CreateObject("Chilkat.PrivateKey")
success = privkey.LoadPem(sbPrivateKeyPem.GetAsString())
If (success <> 1) Then
    outFile.WriteLine(privkey.LastErrorText)
    WScript.Quit
End If

' Prepare an RSA object w/ the private key...
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Rsa")
set rsa = CreateObject("Chilkat.Rsa")
success = rsa.ImportPrivateKeyObj(privkey)
If (success <> 1) Then
    outFile.WriteLine(rsa.LastErrorText)
    WScript.Quit
End If

' RSA will be used to decrypt the xenc:EncryptedKey
' The bytes to be decrypted are in xenc:CipherValue (in base64 format)
encryptedAesKey = xml.GetChildContent("saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:CipherData|xenc:CipherValue")
If (xml.LastMethodSuccess <> 1) Then
    outFile.WriteLine("Encrypted AES key not found.")
    WScript.Quit
End If

outFile.WriteLine("Encrypted AES key (base64) = " & encryptedAesKey)

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.BinData")
set bdAesKey = CreateObject("Chilkat.BinData")
success = bdAesKey.AppendEncoded(encryptedAesKey,"base64")

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbRsaAlg = CreateObject("Chilkat.StringBuilder")
success = sbRsaAlg.Append(xml.ChilkatPath("saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:EncryptionMethod|(Algorithm)"))
outFile.WriteLine("sbRsaAlg contains: " & sbRsaAlg.GetAsString())
If (sbRsaAlg.Contains("rsa-oaep",1) = 1) Then
    rsa.OaepPadding = 1
End If

' Note: The DecryptBd method is introduced in Chilkat v9.5.0.76
success = rsa.DecryptBd(bdAesKey,1)
If (success <> 1) Then
    outFile.WriteLine(rsa.LastErrorText)
    WScript.Quit
End If

outFile.WriteLine("Decrypted AES key (hex) = " & bdAesKey.GetEncoded("hex"))

' Get the encrypted XML (in base64) to be decrypted w/ the AES key.
encrypted64 = xml.GetChildContent("saml2:EncryptedAssertion|xenc:EncryptedData|xenc:CipherData|xenc:CipherValue")
If (xml.LastMethodSuccess <> 1) Then
    outFile.WriteLine("Encrypted data not found.")
    WScript.Quit
End If

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.BinData")
set bdEncrypted = CreateObject("Chilkat.BinData")
success = bdEncrypted.AppendEncoded(encrypted64,"base64")

' Get the symmetric algorithm:  "http://www.w3.org/2001/04/xmlenc#aes128-cbc"
' and set the symmetric decrypt properties.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Crypt2")
set crypt = CreateObject("Chilkat.Crypt2")
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbAlg = CreateObject("Chilkat.StringBuilder")
success = sbAlg.Append(xml.ChilkatPath("saml2:EncryptedAssertion|xenc:EncryptedData|xenc:EncryptionMethod|(Algorithm)"))
If (sbAlg.Contains("aes128-cbc",1) = 1) Then
    crypt.CryptAlgorithm = "aes"
    crypt.KeyLength = 128
    crypt.CipherMode = "cbc"
    ' The 1st 16 bytes of the encrypted data are the AES IV.
    crypt.SetEncodedIV bdEncrypted.GetEncodedChunk(0,16,"hex"),"hex"
    success = bdEncrypted.RemoveChunk(0,16)
End If

' Other algorithms, key lengths, etc, can be supported by checking for different Algorithm attribute values..

crypt.SetEncodedKey bdAesKey.GetEncoded("hex"),"hex"

' AES decrypt...
success = crypt.DecryptBd(bdEncrypted)
If (success <> 1) Then
    outFile.WriteLine(crypt.LastErrorText)
    WScript.Quit
End If

' Get the decrypted XML
decryptedXml = bdEncrypted.GetString("utf-8")
outFile.WriteLine("Decrypted XML:")
outFile.WriteLine(decryptedXml)

' The decrypted XML looks like this:

' <saml2:Assertion xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion" ID="_226e565c548db7986d165d7d969b48b4" IssueInstant="2018-10-11T17:46:20.727Z" Version="2.0">
' ...
' ...
' ...
' </saml2:Assertion>

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Xml")
set xmlAssertion = CreateObject("Chilkat.Xml")
success = xmlAssertion.LoadXml(decryptedXml)

' Replace the saml2:EncryptedAssertion XML subtree with the saml2:Assertion XML.
' xmlEncryptedAssertion is a Chilkat.Xml
Set xmlEncryptedAssertion = xml.FindChild("saml2:EncryptedAssertion")
success = xmlEncryptedAssertion.SwapTree(xmlAssertion)

' The decrypted XML assertion has now replaced the encrypted XML assertion.
' Examine the fully decrypted XML document:
outFile.WriteLine("Full XML SAML document with decrypted assertion:")
outFile.WriteLine(xml.GetXml())

outFile.Close