(Lianja) Decrypt a SAML Response

Demonstrates how to decrypt a SAML response.

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

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//  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:
loHttp = createobject("CkHttp")
loSbSamlResponse = createobject("CkStringBuilder")
loSbPrivateKeyPem = createobject("CkStringBuilder")
llSuccess = loHttp.QuickGetSb("https://chilkatdownload.com/data/samlresponse.xml",loSbSamlResponse)
if (llSuccess = .T.) then
    llSuccess = loHttp.QuickGetSb("https://chilkatdownload.com/data/samlresponse_privkey.pem",loSbPrivateKeyPem)
endif

if (llSuccess <> .T.) then
    ? loHttp.LastErrorText
    release loHttp
    release loSbSamlResponse
    release loSbPrivateKeyPem
    return
endif

loXml = createobject("CkXml")
loXml.LoadSb(loSbSamlResponse,.T.)

//  Load the RSA private key..
loPrivkey = createobject("CkPrivateKey")
llSuccess = loPrivkey.LoadPem(loSbPrivateKeyPem.GetAsString())
if (llSuccess <> .T.) then
    ? loPrivkey.LastErrorText
    release loHttp
    release loSbSamlResponse
    release loSbPrivateKeyPem
    release loXml
    release loPrivkey
    return
endif

//  Prepare an RSA object w/ the private key...
loRsa = createobject("CkRsa")
llSuccess = loRsa.ImportPrivateKeyObj(loPrivkey)
if (llSuccess <> .T.) then
    ? loRsa.LastErrorText
    release loHttp
    release loSbSamlResponse
    release loSbPrivateKeyPem
    release loXml
    release loPrivkey
    release loRsa
    return
endif

//  RSA will be used to decrypt the xenc:EncryptedKey
//  The bytes to be decrypted are in xenc:CipherValue (in base64 format)
lcEncryptedAesKey = loXml.GetChildContent("saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:CipherData|xenc:CipherValue")
if (loXml.LastMethodSuccess <> .T.) then
    ? "Encrypted AES key not found."
    release loHttp
    release loSbSamlResponse
    release loSbPrivateKeyPem
    release loXml
    release loPrivkey
    release loRsa
    return
endif

? "Encrypted AES key (base64) = " + lcEncryptedAesKey

loBdAesKey = createobject("CkBinData")
loBdAesKey.AppendEncoded(lcEncryptedAesKey,"base64")

loSbRsaAlg = createobject("CkStringBuilder")
loSbRsaAlg.Append(loXml.ChilkatPath("saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:EncryptionMethod|(Algorithm)"))
? "sbRsaAlg contains: " + loSbRsaAlg.GetAsString()
if (loSbRsaAlg.Contains("rsa-oaep",.T.) = .T.) then
    loRsa.OaepPadding = .T.
endif

//  Note: The DecryptBd method is introduced in Chilkat v9.5.0.76
llSuccess = loRsa.DecryptBd(loBdAesKey,.T.)
if (llSuccess <> .T.) then
    ? loRsa.LastErrorText
    release loHttp
    release loSbSamlResponse
    release loSbPrivateKeyPem
    release loXml
    release loPrivkey
    release loRsa
    release loBdAesKey
    release loSbRsaAlg
    return
endif

? "Decrypted AES key (hex) = " + loBdAesKey.GetEncoded("hex")

//  Get the encrypted XML (in base64) to be decrypted w/ the AES key.
lcEncrypted64 = loXml.GetChildContent("saml2:EncryptedAssertion|xenc:EncryptedData|xenc:CipherData|xenc:CipherValue")
if (loXml.LastMethodSuccess <> .T.) then
    ? "Encrypted data not found."
    release loHttp
    release loSbSamlResponse
    release loSbPrivateKeyPem
    release loXml
    release loPrivkey
    release loRsa
    release loBdAesKey
    release loSbRsaAlg
    return
endif

loBdEncrypted = createobject("CkBinData")
loBdEncrypted.AppendEncoded(lcEncrypted64,"base64")

//  Get the symmetric algorithm:  "http://www.w3.org/2001/04/xmlenc#aes128-cbc"
//  and set the symmetric decrypt properties.
loCrypt = createobject("CkCrypt2")
loSbAlg = createobject("CkStringBuilder")
loSbAlg.Append(loXml.ChilkatPath("saml2:EncryptedAssertion|xenc:EncryptedData|xenc:EncryptionMethod|(Algorithm)"))
if (loSbAlg.Contains("aes128-cbc",.T.) = .T.) then
    loCrypt.CryptAlgorithm = "aes"
    loCrypt.KeyLength = 128
    loCrypt.CipherMode = "cbc"
    //  The 1st 16 bytes of the encrypted data are the AES IV.
    loCrypt.SetEncodedIV(loBdEncrypted.GetEncodedChunk(0,16,"hex"),"hex")
    loBdEncrypted.RemoveChunk(0,16)
endif

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

loCrypt.SetEncodedKey(loBdAesKey.GetEncoded("hex"),"hex")

//  AES decrypt...
llSuccess = loCrypt.DecryptBd(loBdEncrypted)
if (llSuccess <> .T.) then
    ? loCrypt.LastErrorText
    release loHttp
    release loSbSamlResponse
    release loSbPrivateKeyPem
    release loXml
    release loPrivkey
    release loRsa
    release loBdAesKey
    release loSbRsaAlg
    release loBdEncrypted
    release loCrypt
    release loSbAlg
    return
endif

//  Get the decrypted XML
lcDecryptedXml = loBdEncrypted.GetString("utf-8")
? "Decrypted XML:"
? lcDecryptedXml

//  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>

loXmlAssertion = createobject("CkXml")
loXmlAssertion.LoadXml(lcDecryptedXml)

//  Replace the saml2:EncryptedAssertion XML subtree with the saml2:Assertion XML.
loXmlEncryptedAssertion = loXml.FindChild("saml2:EncryptedAssertion")
loXmlEncryptedAssertion.SwapTree(loXmlAssertion)
release loXmlEncryptedAssertion

//  The decrypted XML assertion has now replaced the encrypted XML assertion.
//  Examine the fully decrypted XML document:
? "Full XML SAML document with decrypted assertion:"
? loXml.GetXml()


release loHttp
release loSbSamlResponse
release loSbPrivateKeyPem
release loXml
release loPrivkey
release loRsa
release loBdAesKey
release loSbRsaAlg
release loBdEncrypted
release loCrypt
release loSbAlg
release loXmlAssertion