Re: Problem in Decryption

[Vishal Mahajan]

Hi Berin,

I agree with your reading of the spec. But, the spec does not prevent 
the encrypter from putting whitespaces between the tags of EncryptedData 
and its parent node. Also there are example encrypted documents like the 
following in the spec:

     <EncryptedData xmlns='http://www.w3.org/2001/04/xmlenc#'
      Type='http://www.w3.org/2001/04/xmlenc#Content'>
       <CipherData>
         <CipherValue>A23B45C56</CipherValue>
       </CipherData>
     </EncryptedData>
Other thing to note is that if the document was signed prior to 
encryption, the signature verification would fail. I think this is an 
important interop issue. What do you think?

Thanks,
Vishal
Berin Lautenbach wrote:

Vishal,

I ran accross this when I was doing the checks for the Merlin Interop
examples - which have white space prior to the EncryptedData node, even
when that node is of type "element content".  According to the spec (from
section 4.2) :
#####################################
"The decryptor SHOULD support the ability to replace the EncryptedData
element with the decrypted 'element' or element 'content' represented by
the UTF-8 encoded characters. The decryptor is NOT REQUIRED to perform
validation on the result of this replacement operation."
######################################
The key words for me were in the first sentance - "...replace the
EncryptedData element with the decrypted 'element' or element
'content'...".
There is no mention of the parent of the EncryptedData, or any of the
surrounding nodes, so my reading is that the libraries (both the C++ and
Java libraries have this behaviour) are doing the correct thing.
Happy to be corrected if someone can find something else in the spec!
Cheers,
    Berin
 

Hi All,

I think there is a problem in the decryption process of the XMLCipher
class. To put the problem across, here's my question:
If there is some whitespace between the tags of EncryptedData and its
parent (See the example below) and the Type attribute of the
EncryptedData corresponds to "element content", then the current
implementation simply replaces the EncryptedData with the decrypted
DocumentFragment. Shouldn't it first remove the existing contents
(whitespace, etc) of the parent node of EncryptedData and then do an
appendChild(DocumentFragment) on the parent?
 <CreditCard Limit='5,000' Currency='USD'>
   <EncryptedData xmlns='http://www.w3.org/2001/04/xmlenc#'
    Type='http://www.w3.org/2001/04/xmlenc#Content'>
     <CipherData>
       <CipherValue>A23B45C56</CipherValue>
     </CipherData>
   </EncryptedData>
 </CreditCard>
If this is accepted as a bug, I even have a patch for it. Should I also
raise a bugzilla?
Thanks,
Vishal