This plugin can be used to "seal" your *.ijm files

Safe_Macro.java

import java.io.File;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.MessageDigest;

import ij.IJ;
import ij.gui.GenericDialog;
import ij.plugin.PlugIn;

/**
 * This plugin can be used to "seal" your *.ijm files by adding a hash of the file content to the filename.
 * Then you can use the same plugin to run these files, and the hash will be checked against the current file content,
 * and the macro is run if the content didn't change, or it will fail with a message that the macro was changed.
 * 
 * @author jmutterer
 */

public class Safe_Macro implements PlugIn {

	public void run(String arg) {
		GenericDialog gd = new GenericDialog("Select Macro File to Seal");
		gd.addChoice("Action", new String[] { "Seal", "Run" }, "Seal");
		gd.addChoice("Hash method", new String[] { "MD5", "SHA-256" }, "MD5");
		gd.addFileField("Macro file", IJ.getDirectory("imagej"));
		gd.showDialog();
		if (gd.wasCanceled())
			return;
		String action = gd.getNextChoice();
		String method = gd.getNextChoice();
		String macro = gd.getNextString();

		if (!macro.toLowerCase().endsWith(".ijm")) {
			IJ.error("Only works with *.ijm macros");
			return;
		}
		if (action == "Seal") {
			File f1 = new File(macro);
			File f2 = new File(macro.substring(0, macro.lastIndexOf(".")) + "_" + getHash(macro, method) + ".ijm");
			boolean success = f1.renameTo(f2);
			if (!success)
				IJ.error("Couldn't rename macro.");
		} else {
			String fileHash = getHash(macro, method);
			String filenameHash = macro.substring(macro.lastIndexOf("_") + 1, macro.lastIndexOf("."));
			if (fileHash.equals(filenameHash)) {
				IJ.runMacroFile(macro);
			} else {
				IJ.error("Couldn't run macro. Hash do not match.");
			}
		}
	}

	private String getHash(String s, String m) {
		try {
			MessageDigest digest = MessageDigest.getInstance(m);
			Path path = Paths.get(s);
			byte[] encodedhash = digest.digest(Files.readAllBytes(path));
			return bytesToHex(encodedhash);
		} catch (Exception e) {
		}
		return "0";
	}

	private static String bytesToHex(byte[] hash) {
		StringBuilder hexString = new StringBuilder(2 * hash.length);
		for (int i = 0; i < hash.length; i++) {
			String hex = Integer.toHexString(0xff & hash[i]);
			if (hex.length() == 1) {
				hexString.append('0');
			}
			hexString.append(hex);
		}
		return hexString.toString();
	}
}