Hashing

gistfile1.java

	private byte[] generateHash() {
		MessageDigest messageDigestInstance = null;
		byte[] hash = null;
		try {
			messageDigestInstance = MessageDigest.getInstance("SHA-1");
			DigestInputStream dis = new DigestInputStream(new DataInputStream(
					new FileInputStream(this)), messageDigestInstance);

			while (dis.read() != -1)
				;
			dis.close();
			hash = messageDigestInstance.digest();

		} catch (FileNotFoundException e) {
			System.err
					.println("File not found while generating hash for DataFile.");
		} catch (NoSuchAlgorithmException e) {
			System.err
					.println("Algorithm does not exist while generating hash for DataFile.");
		} catch (IOException e) {
			System.err
					.println("I/O Exception while generating hash for DataFile.");
		}
		return hash;
	}