Re: Decrypt using KeyInfo

[Berin Lautenbach]

Hyejung,

Oops.  I missed this - apologies!

Did you get this working?  My first thought would be that you are trying 
to create a key using

SecretKeySpec ks = new
    SecretKeySpec(encryptionKeyCipherValue.getValue().getBytes(),
                  ek.getEncryptionMethod().getAlgorithm());
Which will fail, as the bytes you are using are encrypted bytes from the 
doc, and the algorithm is an xml-encryption algorithm, not a JCE algorithm.

If you are still having problems, come back to the list and we will see 
what we can do.

Cheers,
        Berin
Hye-Jung Kim wrote:

Hello,
I am trying to decrypt the encrypted xml data using KeyInfo.
I extracted CipherValue of KeyInfo  which is kek(key encryption key) to 
pass on to my XmlCipher however, I am getting the exception 
java.security.NoSuchAlgorithmException: Algorithm 
http://www.w3.org/2001/04/xmlenc#kw-tripledes not available.  I've tried 
different provider but still failed to retrieve kek value from KeyInfo. 
I am not sure what I am doing wrong to retrieve kek value in order to 
decrypt xml data from KeyInfo ? 

Thanks in advance.

hyejung

==========  my java code =====================

    Key key = null;
    Element e = (Element) 
encryptedDoc.getElementsByTagNameNS(EncryptionConstants.EncryptionSpecNS,
          EncryptionConstants._TAG_ENCRYPTEDDATA).item(0);   
    cipher = XMLCipher.getInstance();
    cipher.init(XMLCipher.DECRYPT_MODE, null);
  
    EncryptedData encryptedData = cipher.loadEncryptedData(encryptedDoc, e);
     
    if(encryptedData == null) {
             throw new Exception("EncryptedData is null");
    }else if (encryptedData.getKeyInfo() == null) {
             throw new Exception("KeyInfo of the EncryptedData is null");
    }
    EncryptedKey ek = encryptedData.getKeyInfo().itemEncryptedKey(0);
  
    *if (ek != null) {
         CipherValue encryptionKeyCipherValue = 
ek.getCipherData().getCipherValue();
         SecretKeySpec ks = new 
SecretKeySpec(encryptionKeyCipherValue.getValue().getBytes(),ek.getEncryptionMethod().getAlgorithm()); 
     
         Key kek = keyFactory.generateSecret(ks);
         XMLCipher keyCipher = XMLCipher.getInstance();
         keyCipher.init(XMLCipher.UNWRAP_MODE, kek);
         key = keyCipher.decryptKey(ek, 
encryptedData.getEncryptionMethod().getAlgorithm());
    }
  
*    //initialize the XMLCipher
    XMLCipher cipher3 = XMLCipher.getInstance();
    cipher3.init(XMLCipher.DECRYPT_MODE, key);
    Document decryptedDoc = cipher.doFinal(encryptedDoc, e);
    XMLUtils.outputDOM(decryptedDoc, output); 
 
======   my encrypted xml data ===============
<xenc:EncryptedData 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#tripledes-cbc*"; 
xmlns:xenc="*http://www.w3.org/2001/04/xmlenc#*"; />
*-* 
<file:///W:/Rhapsody/XMLSecurityFilter/resources/processed/encryptedWithKeyInfo.xml#> 
<ds:KeyInfo xmlns:ds="*http://www.w3.org/2000/09/xmldsig#*";>
*-* 
<file:///W:/Rhapsody/XMLSecurityFilter/resources/processed/encryptedWithKeyInfo.xml#> 
<xenc:EncryptedKey xmlns:xenc="*http://www.w3.org/2001/04/xmlenc#*";>
* * <xenc:EncryptionMethod 
Algorithm="*http://www.w3.org/2001/04/xmlenc#kw-tripledes*"; 
xmlns:xenc="*http://www.w3.org/2001/04/xmlenc#*"; />
*-* 
<file:///W:/Rhapsody/XMLSecurityFilter/resources/processed/encryptedWithKeyInfo.xml#> 
<xenc:CipherData xmlns:xenc="*http://www.w3.org/2001/04/xmlenc#*";>
* * <xenc:CipherValue 
xmlns:xenc="*http://www.w3.org/2001/04/xmlenc#*";>*LYhDusdc65NgbAxiX1uxp7elPwp4s9qQb6dtXu1uFE6p/Wm3+/fiNQ==*</xenc:CipherValue> 

* * </xenc:CipherData>
* * </xenc:EncryptedKey>
* * </ds:KeyInfo>
*-* 
<file:///W:/Rhapsody/XMLSecurityFilter/resources/processed/encryptedWithKeyInfo.xml#> 
<xenc:CipherData xmlns:xenc="*http://www.w3.org/2001/04/xmlenc#*";>
* * <xenc:CipherValue 
xmlns:xenc="*http://www.w3.org/2001/04/xmlenc#*";>*TxuXWSIU/xR8OEhVQt1GxIC/9ItnLWhC1/58eC8p3wPHRoKrO3vYn7LMlCLheprq*</xenc:CipherValue> 

* * </xenc:CipherData>
* * </xenc:EncryptedData>