/*
 * SignHandler.java (för 10.1)
 * Karl-Adam Karlsson
 * 06-10-05
 *
 * java SignHandler <data> <privateKey> <signature> som signerar filen <data> med (den privata) nyckeln <privateKey> och  * sparar signaturen i <signature> 
 *
 */
import javax.crypto.*;
import java.security.*;
import java.io.*;


public class SignHandler{

	public SignHandler(String dataName, String keyName, String sigName){
		signAndSave(getInS(dataName),loadKey(keyName), sigName);
	}//end of constructor





	private void signAndSave(FileInputStream inStream, Key aKey, String sigName){
		File aFile  = new File(sigName);
		Signature aSig = null;
		byte[] signature = null;
		
		try{
			aSig = Signature.getInstance( "SHA1withDSA" );
			aSig.initSign( (PrivateKey)aKey );
		}catch(NoSuchAlgorithmException noAl){
			System.err.println(noAl);
			System.exit(1);	
		}catch(InvalidKeyException inKey){
			System.err.println(inKey);
			System.exit(1);	
		}
		

		int aLen;
		byte[] buffLn = new byte[1024];
		
		try{
	        	while ((aLen = inStream.read(buffLn)) != -1) {
    	    	             aSig.update( buffLn );
        		}
        		
        		signature = aSig.sign();
        		saveSig(sigName, signature);        
				inStream.close();
				
        }catch(IOException ioe){
        	System.err.println(ioe);
			System.exit(1);	
        }catch(SignatureException sigEx){
        	System.err.println(sigEx);
			System.exit(1);	
        }
	}

	/*
	* getInS
	* Returns a FileInputStream connected to a file
	* @param String fimeName The name of the file to connect the stream to.
	* @return FileInputStream A stream connected to the file.
	*/
	private FileInputStream getInS(String fileName){
		FileInputStream inFstream = null;
		
		try{
			inFstream = new FileInputStream(fileName);
		}catch(FileNotFoundException fEx){
			System.err.print(fEx);
			System.exit(1);
		}
	return inFstream;	
	}//end of getInS

	/*
	* SaveSig saves a Signature to file.
	* Both Signature to be saved and filename are parameters.
 	*
	* @param String fileName The file to save to.
	* @param byte[] aSig The Signature, in bytes, to be saved.
	*
	*/
	private void saveSig(String fileName, byte[] aSig){	
		File outFile  = new File(fileName);          
		FileOutputStream outStream;            
		
		try{
   			outStream = new FileOutputStream(fileName);
        	outStream.write(aSig);
       		outStream.close();
   		
		} catch(IOException e) {
   			System.err.println("IO Exception");
   			e.printStackTrace();
   			System.exit(1);
		}
			
	}//endof saveSig
	


	/*
	* loadKey
	* Loads a Key Object from the file named <keyFileName>
	* @param keyFileName Name of file to load key from
	* @return Key the loaded key.
	*/
	private Key loadKey(String keyFileName){
		ObjectInputStream oInStr = null;
		Key theKey = null;
		
		try{
			FileInputStream inFstream = new FileInputStream(keyFileName);
			oInStr = new ObjectInputStream(inFstream);
		}catch(FileNotFoundException fEx){
			System.err.print(fEx);
			System.exit(1);
		}catch(IOException ioe){
			System.err.print(ioe);
			System.exit(1);
		}
		
		try{
			theKey = (PrivateKey)oInStr.readObject();
			oInStr.close();
		}catch(IOException io2){
			System.err.print(io2);
			System.exit(1);	
		}catch(ClassNotFoundException cNf){
			System.err.print(cNf);
			System.exit(1);
		}
	
	return theKey;
	}//end of loadKey

	/*
	* main
	* 
	*/
	public static void main (String[] args) {
		if(args==null || args.length < 3 ||args.length>3){
			System.out.println("Usage: java SignHandler <data> <privateKey> <signature>");
			System.out.println("Where <data> is the file to sign.");
			System.out.println("Where <privateKey> is the name of private keyfile to use for signing.");
			System.out.println("Where <signature> is desired name of the signature file.");
		}
		else if(args.length==3&&args[0]!=null&&args[1]!=null&&args[2]!=null){
			new SignHandler(args[0],args[1],args[2]);
		}
		else if(args[0]==null||args[1]==null||args[2]==null){
			System.out.println("Usage: java SignHandler <data> <privateKey> <signature>");
			System.out.println("Where <data> is the file to sign.");
			System.out.println("Where <privateKey> is the name of private keyfile to use for signing.");
			System.out.println("Where <signature> is desired name of the signature file.");
		}
  		
  	}//end of main
}//end of class