code: public byte[] processBlock(
          byte[]  in,
          int     inOff,
          int     inLen)
      {
          if (core == null)
          {
              throw new IllegalStateException("RSA engine not initialised");
          }
  
          return core.convertOutput(core.processBlock(core.convertInput(in, inOff, inLen)));
      }
docs: Process a single block using the basic RSA algorithm.
  
  @param in the input array.
  @param inOff the offset into the input buffer where the data starts.
  @param inLen the length of the data to be processed.
  @return the result of the RSA process.
  @exception DataLengthException the input block is too large.