(Unicode C++) 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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#include <CkHttpW.h>
#include <CkStringBuilderW.h>
#include <CkXmlW.h>
#include <CkPrivateKeyW.h>
#include <CkRsaW.h>
#include <CkBinDataW.h>
#include <CkCrypt2W.h>

void ChilkatSample(void)
    {
    //  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:
    CkHttpW http;
    CkStringBuilderW sbSamlResponse;
    CkStringBuilderW sbPrivateKeyPem;
    bool success = http.QuickGetSb(L"https://chilkatdownload.com/data/samlresponse.xml",sbSamlResponse);
    if (success == true) {
        success = http.QuickGetSb(L"https://chilkatdownload.com/data/samlresponse_privkey.pem",sbPrivateKeyPem);
    }

    if (success != true) {
        wprintf(L"%s\n",http.lastErrorText());
        return;
    }

    CkXmlW xml;
    xml.LoadSb(sbSamlResponse,true);

    //  Load the RSA private key..
    CkPrivateKeyW privkey;
    success = privkey.LoadPem(sbPrivateKeyPem.getAsString());
    if (success != true) {
        wprintf(L"%s\n",privkey.lastErrorText());
        return;
    }

    //  Prepare an RSA object w/ the private key...
    CkRsaW rsa;
    success = rsa.ImportPrivateKeyObj(privkey);
    if (success != true) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    //  RSA will be used to decrypt the xenc:EncryptedKey
    //  The bytes to be decrypted are in xenc:CipherValue (in base64 format)
    const wchar_t *encryptedAesKey = xml.getChildContent(L"saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:CipherData|xenc:CipherValue");
    if (xml.get_LastMethodSuccess() != true) {
        wprintf(L"Encrypted AES key not found.\n");
        return;
    }

    wprintf(L"Encrypted AES key (base64) = %s\n",encryptedAesKey);

    CkBinDataW bdAesKey;
    bdAesKey.AppendEncoded(encryptedAesKey,L"base64");

    CkStringBuilderW sbRsaAlg;
    sbRsaAlg.Append(xml.chilkatPath(L"saml2:EncryptedAssertion|xenc:EncryptedData|ds:KeyInfo|xenc:EncryptedKey|xenc:EncryptionMethod|(Algorithm)"));
    wprintf(L"sbRsaAlg contains: %s\n",sbRsaAlg.getAsString());
    if (sbRsaAlg.Contains(L"rsa-oaep",true) == true) {
        rsa.put_OaepPadding(true);
    }

    //  Note: The DecryptBd method is introduced in Chilkat v9.5.0.76
    success = rsa.DecryptBd(bdAesKey,true);
    if (success != true) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    wprintf(L"Decrypted AES key (hex) = %s\n",bdAesKey.getEncoded(L"hex"));

    //  Get the encrypted XML (in base64) to be decrypted w/ the AES key.
    const wchar_t *encrypted64 = xml.getChildContent(L"saml2:EncryptedAssertion|xenc:EncryptedData|xenc:CipherData|xenc:CipherValue");
    if (xml.get_LastMethodSuccess() != true) {
        wprintf(L"Encrypted data not found.\n");
        return;
    }

    CkBinDataW bdEncrypted;
    bdEncrypted.AppendEncoded(encrypted64,L"base64");

    //  Get the symmetric algorithm:  "http://www.w3.org/2001/04/xmlenc#aes128-cbc"
    //  and set the symmetric decrypt properties.
    CkCrypt2W crypt;
    CkStringBuilderW sbAlg;
    sbAlg.Append(xml.chilkatPath(L"saml2:EncryptedAssertion|xenc:EncryptedData|xenc:EncryptionMethod|(Algorithm)"));
    if (sbAlg.Contains(L"aes128-cbc",true) == true) {
        crypt.put_CryptAlgorithm(L"aes");
        crypt.put_KeyLength(128);
        crypt.put_CipherMode(L"cbc");
        //  The 1st 16 bytes of the encrypted data are the AES IV.
        crypt.SetEncodedIV(bdEncrypted.getEncodedChunk(0,16,L"hex"),L"hex");
        bdEncrypted.RemoveChunk(0,16);
    }

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

    crypt.SetEncodedKey(bdAesKey.getEncoded(L"hex"),L"hex");

    //  AES decrypt...
    success = crypt.DecryptBd(bdEncrypted);
    if (success != true) {
        wprintf(L"%s\n",crypt.lastErrorText());
        return;
    }

    //  Get the decrypted XML
    const wchar_t *decryptedXml = bdEncrypted.getString(L"utf-8");
    wprintf(L"Decrypted XML:\n");
    wprintf(L"%s\n",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>

    CkXmlW xmlAssertion;
    xmlAssertion.LoadXml(decryptedXml);

    //  Replace the saml2:EncryptedAssertion XML subtree with the saml2:Assertion XML.
    CkXmlW *xmlEncryptedAssertion = xml.FindChild(L"saml2:EncryptedAssertion");
    xmlEncryptedAssertion->SwapTree(xmlAssertion);
    delete xmlEncryptedAssertion;

    //  The decrypted XML assertion has now replaced the encrypted XML assertion.
    //  Examine the fully decrypted XML document:
    wprintf(L"Full XML SAML document with decrypted assertion:\n");
    wprintf(L"%s\n",xml.getXml());
    }