RE: Remote private key

[Lopez Cantero, Sergio]

This is because before you sign it, you have to encode in DER the digest with 
something like:

(Using bouncycastle classes)

      public static byte[] doDER(byte[] data) throws IOException {

//This OID is for SHA1 only

            String hashOID = 1.3.14.3.2.26;

            DigestInfo dInfo = new DigestInfo(new AlgorithmIdentifier(

                        new DERObjectIdentifier(hashOID), null), data);

            return dInfo.getEncoded(ASN1Encodable.DER);

      }

I recommend sending the digested hash, not the entire byte secuence, so you can 
do DER  it and sign it with "NONEwithRSA" algorithm afterwards.

De: Legido Martínez, Isidoro [mailto:[EMAIL PROTECTED] 
Enviado el: martes, 05 de agosto de 2008 23:21
Para: security-dev@xml.apache.org
Asunto: Re: Remote private key

 

Hi:

I'm still having problems. After building the Signature element (everything but 
the SignatureValue element) I execute:

  [Server side]
  XMLSignature sig = .... -> It uses http://www.w3.org/2000/09/xmldsig#rsa-sha1 
as signature method
  sig.getSignedInfo().generateDigestValues();
  byte[] data2Sign = sig.getSignedInfo().getCanonicalizedOctetStream();

then, the Server sends 'data2Sign' to the Client (encoded) and the client 
executes

[Client side]
  PrivateKey pKey = ....
  Signature signature = Signature.getInstance("SHA1withRSA");
  signature.initSign(privateKey);
  signature.update(data2Sign); --> data2Sign is the decoded data received from 
the Server
  byte[] dataSigned =  signature.sign();

then, the Client sends back to the Server 'dataSigned' (encoded) and the server 
adds it to the SignatureValue element (decoded). 

But the signature build this way is not valid :-( If I execute 
XMLSignature.sign() directly, the signature I get is different. What I'm doing 
wrong? 

As you can see, the server sends directly the C14N data, not the digested one. 
I have also tried digesting it before with the same result. In fact, I am doing 
the same that XMLSignature.sign()'s method, so I can't see where the problem is.

Does anybody have an idea?

Thanks a lot

Isi




2008/7/29 Lopez Cantero, Sergio <[EMAIL PROTECTED]>

As far as I know, yes, you have to digest them "by hand"

 

I hope to have helped you.

 

Sergio

 


 

        De: Legido Martínez, Isidoro [mailto:[EMAIL PROTECTED] 
        Enviado el: martes, 29 de julio de 2008 8:41

        
        Para: security-dev@xml.apache.org

        Asunto: Re: Remote private key

         

        Thanks
        
        So, how can I get the digested value? Do I have to digest them "by 
hand"?
        
        Thanks
        
        Isi

        2008/7/29 Lopez Cantero, Sergio <[EMAIL PROTECTED]>

        Hi Isidoro, 

        getCanonicalizedOctetStream returns the bytes you have to digest, not 
the digested data, so that's the difference.

        Concerning the way to put back the signature, you can get the signature 
element and search through the DOM for the SignatureValue Element to fill its 
contents.

        I'm doing something like that ;)

         

        Sergio

         

        De: Legido Martínez, Isidoro [mailto:[EMAIL PROTECTED] 
        Enviado el: lunes, 28 de julio de 2008 21:45
        Para: security-dev@xml.apache.org
        Asunto: Remote private key

         

        Hi everybody:
        
        Firs, I will try to explain my current situation (sorry in advanced for 
my poor English :-( ). My signing system is splitted in two pieces: a 
lightweith client that owns the private key and ONLY can sign (no digest) and 
the server side that does everything else EXCEPT signing (digest, add Manifest 
elements or aditional References). 
        My initial idea was: the server side builds the SignedInfo elements, 
get its digest and send it to the client. The client signs and send the result 
to the server, which adds this to the SignedInfo. Is that possible withe the 
current implementation? 
        I expected that
        
          SignedInfo si.generateDigestValues();
          String digest = Base64.encode(si.getCanonicalizedOctetStream());
        
        'digest' would contain the digest value in Base64, but what I get is 
something different. How can I get the digest? After signing, is there any way 
for adding it to SignInfo.
        
        Thanks a lot
        
        Isi

        
        
        
        -- 
        ,-""""""-.
        /\j__/\ ( \`--.
        [EMAIL PROTECTED]@'/ _) >--.`.
        _{.:Y:_}_{{_,' ) )
        {_}`-^{_} ``` (_/




-- 
,-""""""-.
/\j__/\ ( \`--.
[EMAIL PROTECTED]@'/ _) >--.`.
_{.:Y:_}_{{_,' ) )
{_}`-^{_} ``` (_/