code: public boolean isPassphraseProtected() {
  		ByteArrayReader bar = new ByteArrayReader(keyblob);
  
  		try {
  			String type = bar.readString();
  
  			if (type.equals("none")) {
  				return false;
  			}
  
  			if (type.equalsIgnoreCase("3des-cbc")) {
  				return true;
  			}
  		} catch (IOException ioe) {
  		} finally {
  			try {
  				bar.close();
  			} catch (IOException e) {
  			}
  		}
  
  		return false;
  	}
docs: /*
  (non-Javadoc)
  
  @see com.sshtools.publickey.SshPrivateKeyFile#isPassphraseProtected()