(PHP ActiveX) 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 Note: The php_com_dotnet.dll may need to be enabled inside of php.ini.

<?php

// 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 new COM('Chilkat_9_5_0.Chilkat.Http')
$http = new COM("Chilkat.Http");
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.StringBuilder')
$sbSamlResponse = new COM("Chilkat.StringBuilder");
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.StringBuilder')
$sbPrivateKeyPem = new COM("Chilkat.StringBuilder");
$success = $http->QuickGetSb('https://chilkatdownload.com/data/samlresponse.xml',$sbSamlResponse);
if ($success == 1) {
    $success = $http->QuickGetSb('https://chilkatdownload.com/data/samlresponse_privkey.pem',$sbPrivateKeyPem);
}

if ($success != 1) {
    print $http->LastErrorText . "\n";
    exit;
}

// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.Xml')
$xml = new COM("Chilkat.Xml");
$xml->LoadSb($sbSamlResponse,1);

// Load the RSA private key..
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.PrivateKey')
$privkey = new COM("Chilkat.PrivateKey");
$success = $privkey->LoadPem($sbPrivateKeyPem->getAsString());
if ($success != 1) {
    print $privkey->LastErrorText . "\n";
    exit;
}

// Prepare an RSA object w/ the private key...
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.Rsa')
$rsa = new COM("Chilkat.Rsa");
$success = $rsa->ImportPrivateKeyObj($privkey);
if ($success != 1) {
    print $rsa->LastErrorText . "\n";
    exit;
}

// 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) {
    print 'Encrypted AES key not found.' . "\n";
    exit;
}

print 'Encrypted AES key (base64) = ' . $encryptedAesKey . "\n";

// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.BinData')
$bdAesKey = new COM("Chilkat.BinData");
$bdAesKey->AppendEncoded($encryptedAesKey,'base64');

// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.StringBuilder')
$sbRsaAlg = new COM("Chilkat.StringBuilder");
$sbRsaAlg->Append($xml->chilkatPath('saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:EncryptionMethod|(Algorithm)'));
print 'sbRsaAlg contains: ' . $sbRsaAlg->getAsString() . "\n";
if ($sbRsaAlg->Contains('rsa-oaep',1) == 1) {
    $rsa->OaepPadding = 1;
}

// Note: The DecryptBd method is introduced in Chilkat v9.5.0.76
$success = $rsa->DecryptBd($bdAesKey,1);
if ($success != 1) {
    print $rsa->LastErrorText . "\n";
    exit;
}

print 'Decrypted AES key (hex) = ' . $bdAesKey->getEncoded('hex') . "\n";

// 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) {
    print 'Encrypted data not found.' . "\n";
    exit;
}

// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.BinData')
$bdEncrypted = new COM("Chilkat.BinData");
$bdEncrypted->AppendEncoded($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 new COM('Chilkat_9_5_0.Chilkat.Crypt2')
$crypt = new COM("Chilkat.Crypt2");
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.StringBuilder')
$sbAlg = new COM("Chilkat.StringBuilder");
$sbAlg->Append($xml->chilkatPath('saml2:EncryptedAssertion|xenc:EncryptedData|xenc:EncryptionMethod|(Algorithm)'));
if ($sbAlg->Contains('aes128-cbc',1) == 1) {
    $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);
}

// 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) {
    print $crypt->LastErrorText . "\n";
    exit;
}

// Get the decrypted XML
$decryptedXml = $bdEncrypted->getString('utf-8');
print 'Decrypted XML:' . "\n";
print $decryptedXml . "\n";

// 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 new COM('Chilkat_9_5_0.Chilkat.Xml')
$xmlAssertion = new COM("Chilkat.Xml");
$xmlAssertion->LoadXml($decryptedXml);

// Replace the saml2:EncryptedAssertion XML subtree with the saml2:Assertion XML.
// xmlEncryptedAssertion is a Chilkat.Xml
$xmlEncryptedAssertion = $xml->FindChild('saml2:EncryptedAssertion');
$xmlEncryptedAssertion->SwapTree($xmlAssertion);

// The decrypted XML assertion has now replaced the encrypted XML assertion.
// Examine the fully decrypted XML document:
print 'Full XML SAML document with decrypted assertion:' . "\n";
print $xml->getXml() . "\n";

?>