ALG_RSA_SHA_PKCS1 with cyberflex 64k

Question

Hello,
I've tested with success ALG_RSA_PKCS1 , on gemalto cyberflex 32K and even 64k
here is my crypt fonction :
private void encryptRSA(APDU apdu)
          byte a[] = apdu.getBuffer();
          short byteRead = (short) (apdu.setIncomingAndReceive());
          cipherRSA.init(rsa_PrivateCrtKey, Cipher.MODE_ENCRYPT);
          short cyphertext = cipherRSA.doFinal(a, (short) dataOffset, byteRead, a, (short) dataOffset);
          // Send results
          apdu.setOutgoing();
          apdu.setOutgoingLength((short) cyphertext);
          apdu.sendBytesLong(a, (short) dataOffset, (short) cyphertext);
     }but when i couple it with sha1 , i've got a bad error with this code quite similar :
private void signDocs(APDU apdu) {
          byte apduBuffer[] = apdu.getBuffer();              
         short byteRead = (short) (apdu.setIncomingAndReceive());       
     // create signature
         sig.init(rsa_PrivateCrtKey, Signature.MODE_SIGN);
     byte[] sigResult = null;
         short size = sig.sign(apdluBuffer, (short) dataOffset, byteRead, sigResult, (short) dataOffset);
         apdu.setOutgoing();
         apdu.setOutgoingLength((short) size);
         apdu.sendBytesLong(sigResult, (short) dataOffset, (short) size);
i followed everything like in the doc 2.2.1
the two corresponding lines at the beginning are :
public Signature sig=null;
sig = Signature.getInstance(Signature.ALG_RSA_SHA_PKCS1,false);
the compilation and the load of the cardlet is good but when i want to sign :-----------> error 6F00
I'm surprised because RSA without SHA1 works very well , i arrive to export the public key and use it on the pc....
and according to the spec of my 64k card it is compatible with sha1 :
[http://scardshop.com/boutique/fiche_produit.cfm?ref=CPCB64P&type=2&code_lg=lg_fr&num=11 ]
kind regards,
Marc

Answer 1

Hello,
Some news,
when i use the public key in the card like this , it works:
private void signDocs(APDU apdu) {
          byte apduBuffer[] = apdu.getBuffer();              
         short byteRead = (short) (apdu.setIncomingAndReceive());       
     // create signature
         sig.init(rsa_PublicKey, Signature.MODE_SIGN);
     byte[]  sigResult =new byte[(short)128];
         short size = sig.sign(apduBuffer, (short) 0, byteRead, apduBuffer, (short) 0);
         apdu.setOutgoing();
         apdu.setOutgoingLength((short) size);
         apdu.sendBytesLong(apduBuffer, (short) 0, (short) size);
     }when i say it works, it returns a 128 byte array an i haven't verify the signature yet
but that wants to say i will have to export the private key if i wants to decrypt it on the pc
and i will never have to export my public key.... ( wich will be considerated like a private...)
will it work ?
i've found another solution :
http://forums.sun.com/thread.jspa?forumID=23&threadID=5240359
but i would prefer my solution
help me please, i'm very limited in time,
(ps : sorry for my bad english)
kind regards,
Marc