(Delphi ActiveX) Decrypt a SAML Response

Demonstrates how to decrypt a SAML response.

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

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: TChilkatHttp;
sbSamlResponse: TChilkatStringBuilder;
sbPrivateKeyPem: TChilkatStringBuilder;
success: Integer;
xml: TChilkatXml;
privkey: TPrivateKey;
rsa: TChilkatRsa;
encryptedAesKey: WideString;
bdAesKey: TChilkatBinData;
sbRsaAlg: TChilkatStringBuilder;
encrypted64: WideString;
bdEncrypted: TChilkatBinData;
crypt: TChilkatCrypt2;
sbAlg: TChilkatStringBuilder;
decryptedXml: WideString;
xmlAssertion: TChilkatXml;
xmlEncryptedAssertion: IChilkatXml;

begin
// 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:
http := TChilkatHttp.Create(Self);
sbSamlResponse := TChilkatStringBuilder.Create(Self);
sbPrivateKeyPem := TChilkatStringBuilder.Create(Self);
success := http.QuickGetSb('https://chilkatdownload.com/data/samlresponse.xml',sbSamlResponse.ControlInterface);
if (success = 1) then
  begin
    success := http.QuickGetSb('https://chilkatdownload.com/data/samlresponse_privkey.pem',sbPrivateKeyPem.ControlInterface);
  end;
if (success <> 1) then
  begin
    Memo1.Lines.Add(http.LastErrorText);
    Exit;
  end;

xml := TChilkatXml.Create(Self);
xml.LoadSb(sbSamlResponse.ControlInterface,1);

// Load the RSA private key..
privkey := TPrivateKey.Create(Self);
success := privkey.LoadPem(sbPrivateKeyPem.GetAsString());
if (success <> 1) then
  begin
    Memo1.Lines.Add(privkey.LastErrorText);
    Exit;
  end;

// Prepare an RSA object w/ the private key...
rsa := TChilkatRsa.Create(Self);
success := rsa.ImportPrivateKeyObj(privkey.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

// 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
  begin
    Memo1.Lines.Add('Encrypted AES key not found.');
    Exit;
  end;
Memo1.Lines.Add('Encrypted AES key (base64) = ' + encryptedAesKey);

bdAesKey := TChilkatBinData.Create(Self);
bdAesKey.AppendEncoded(encryptedAesKey,'base64');

sbRsaAlg := TChilkatStringBuilder.Create(Self);
sbRsaAlg.Append(xml.ChilkatPath('saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:EncryptionMethod|(Algorithm)'));
Memo1.Lines.Add('sbRsaAlg contains: ' + sbRsaAlg.GetAsString());
if (sbRsaAlg.Contains('rsa-oaep',1) = 1) then
  begin
    rsa.OaepPadding := 1;
  end;

// Note: The DecryptBd method is introduced in Chilkat v9.5.0.76
success := rsa.DecryptBd(bdAesKey.ControlInterface,1);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('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
  begin
    Memo1.Lines.Add('Encrypted data not found.');
    Exit;
  end;
bdEncrypted := TChilkatBinData.Create(Self);
bdEncrypted.AppendEncoded(encrypted64,'base64');

// Get the symmetric algorithm:  "http://www.w3.org/2001/04/xmlenc#aes128-cbc"
// and set the symmetric decrypt properties.
crypt := TChilkatCrypt2.Create(Self);
sbAlg := TChilkatStringBuilder.Create(Self);
sbAlg.Append(xml.ChilkatPath('saml2:EncryptedAssertion|xenc:EncryptedData|xenc:EncryptionMethod|(Algorithm)'));
if (sbAlg.Contains('aes128-cbc',1) = 1) then
  begin
    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');
    bdEncrypted.RemoveChunk(0,16);
  end;
// 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.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// Get the decrypted XML
decryptedXml := bdEncrypted.GetString('utf-8');
Memo1.Lines.Add('Decrypted XML:');
Memo1.Lines.Add(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>

xmlAssertion := TChilkatXml.Create(Self);
xmlAssertion.LoadXml(decryptedXml);

// Replace the saml2:EncryptedAssertion XML subtree with the saml2:Assertion XML.
xmlEncryptedAssertion := xml.FindChild('saml2:EncryptedAssertion');
xmlEncryptedAssertion.SwapTree(xmlAssertion.ControlInterface);

// The decrypted XML assertion has now replaced the encrypted XML assertion.
// Examine the fully decrypted XML document:
Memo1.Lines.Add('Full XML SAML document with decrypted assertion:');
Memo1.Lines.Add(xml.GetXml());
end;