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

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http, Crypt2, StringBuilder, BinData, PrivateKey, Xml, Rsa;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: HCkHttp;
sbSamlResponse: HCkStringBuilder;
sbPrivateKeyPem: HCkStringBuilder;
success: Boolean;
xml: HCkXml;
privkey: HCkPrivateKey;
rsa: HCkRsa;
encryptedAesKey: PWideChar;
bdAesKey: HCkBinData;
sbRsaAlg: HCkStringBuilder;
encrypted64: PWideChar;
bdEncrypted: HCkBinData;
crypt: HCkCrypt2;
sbAlg: HCkStringBuilder;
decryptedXml: PWideChar;
xmlAssertion: HCkXml;
xmlEncryptedAssertion: HCkXml;

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 := CkHttp_Create();
sbSamlResponse := CkStringBuilder_Create();
sbPrivateKeyPem := CkStringBuilder_Create();
success := CkHttp_QuickGetSb(http,'https://chilkatdownload.com/data/samlresponse.xml',sbSamlResponse);
if (success = True) then
  begin
    success := CkHttp_QuickGetSb(http,'https://chilkatdownload.com/data/samlresponse_privkey.pem',sbPrivateKeyPem);
  end;
if (success <> True) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

xml := CkXml_Create();
CkXml_LoadSb(xml,sbSamlResponse,True);

//  Load the RSA private key..
privkey := CkPrivateKey_Create();
success := CkPrivateKey_LoadPem(privkey,CkStringBuilder__getAsString(sbPrivateKeyPem));
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privkey));
    Exit;
  end;

//  Prepare an RSA object w/ the private key...
rsa := CkRsa_Create();
success := CkRsa_ImportPrivateKeyObj(rsa,privkey);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

//  RSA will be used to decrypt the xenc:EncryptedKey
//  The bytes to be decrypted are in xenc:CipherValue (in base64 format)
encryptedAesKey := CkXml__getChildContent(xml,'saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:CipherData|xenc:CipherValue');
if (CkXml_getLastMethodSuccess(xml) <> True) then
  begin
    Memo1.Lines.Add('Encrypted AES key not found.');
    Exit;
  end;
Memo1.Lines.Add('Encrypted AES key (base64) = ' + encryptedAesKey);

bdAesKey := CkBinData_Create();
CkBinData_AppendEncoded(bdAesKey,encryptedAesKey,'base64');

sbRsaAlg := CkStringBuilder_Create();
CkStringBuilder_Append(sbRsaAlg,CkXml__chilkatPath(xml,'saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:EncryptionMethod|(Algorithm)'));
Memo1.Lines.Add('sbRsaAlg contains: ' + CkStringBuilder__getAsString(sbRsaAlg));
if (CkStringBuilder_Contains(sbRsaAlg,'rsa-oaep',True) = True) then
  begin
    CkRsa_putOaepPadding(rsa,True);
  end;

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

Memo1.Lines.Add('Decrypted AES key (hex) = ' + CkBinData__getEncoded(bdAesKey,'hex'));

//  Get the encrypted XML (in base64) to be decrypted w/ the AES key.
encrypted64 := CkXml__getChildContent(xml,'saml2:EncryptedAssertion|xenc:EncryptedData|xenc:CipherData|xenc:CipherValue');
if (CkXml_getLastMethodSuccess(xml) <> True) then
  begin
    Memo1.Lines.Add('Encrypted data not found.');
    Exit;
  end;
bdEncrypted := CkBinData_Create();
CkBinData_AppendEncoded(bdEncrypted,encrypted64,'base64');

//  Get the symmetric algorithm:  "http://www.w3.org/2001/04/xmlenc#aes128-cbc"
//  and set the symmetric decrypt properties.
crypt := CkCrypt2_Create();
sbAlg := CkStringBuilder_Create();
CkStringBuilder_Append(sbAlg,CkXml__chilkatPath(xml,'saml2:EncryptedAssertion|xenc:EncryptedData|xenc:EncryptionMethod|(Algorithm)'));
if (CkStringBuilder_Contains(sbAlg,'aes128-cbc',True) = True) then
  begin
    CkCrypt2_putCryptAlgorithm(crypt,'aes');
    CkCrypt2_putKeyLength(crypt,128);
    CkCrypt2_putCipherMode(crypt,'cbc');
    //  The 1st 16 bytes of the encrypted data are the AES IV.
    CkCrypt2_SetEncodedIV(crypt,CkBinData__getEncodedChunk(bdEncrypted,0,16,'hex'),'hex');
    CkBinData_RemoveChunk(bdEncrypted,0,16);
  end;
//  Other algorithms, key lengths, etc, can be supported by checking for different Algorithm attribute values..

CkCrypt2_SetEncodedKey(crypt,CkBinData__getEncoded(bdAesKey,'hex'),'hex');

//  AES decrypt...
success := CkCrypt2_DecryptBd(crypt,bdEncrypted);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

//  Get the decrypted XML
decryptedXml := CkBinData__getString(bdEncrypted,'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 := CkXml_Create();
CkXml_LoadXml(xmlAssertion,decryptedXml);

//  Replace the saml2:EncryptedAssertion XML subtree with the saml2:Assertion XML.
xmlEncryptedAssertion := CkXml_FindChild(xml,'saml2:EncryptedAssertion');
CkXml_SwapTree(xmlEncryptedAssertion,xmlAssertion);
CkXml_Dispose(xmlEncryptedAssertion);

//  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(CkXml__getXml(xml));

CkHttp_Dispose(http);
CkStringBuilder_Dispose(sbSamlResponse);
CkStringBuilder_Dispose(sbPrivateKeyPem);
CkXml_Dispose(xml);
CkPrivateKey_Dispose(privkey);
CkRsa_Dispose(rsa);
CkBinData_Dispose(bdAesKey);
CkStringBuilder_Dispose(sbRsaAlg);
CkBinData_Dispose(bdEncrypted);
CkCrypt2_Dispose(crypt);
CkStringBuilder_Dispose(sbAlg);
CkXml_Dispose(xmlAssertion);

end;