Co třeba nějak takhle?

public static boolean verifyZipPassword(ZipFile zipFile, String password) {
    try {
        Enumeration<ZipArchiveEntry> entries = zipFile.getEntries();
        ZipArchiveEntry smallestEntry = null;

        while (entries.hasMoreElements()) {
            ZipArchiveEntry entry = entries.nextElement();
            if (smallestEntry == null || entry.getSize() < smallestEntry.getSize()) {
                smallestEntry = entry;
            }
        }

        if (smallestEntry != null) {
            return zipFile.canReadEntryData(smallestEntry, password);
        }

        return true;
    } catch (IOException e) {
        return false;
    }
}