MarpX Privacy starts at this navigation screen. When in doubt, click the Home button to return here. You can switch between handling files and messages. You can also access the help pages (highly recommended) and the Exit button.
The large box lets you type in or paste a message that you would like to make private. Next below is an example in which 155 letters have been typed. It could just as easily been copied and pasted from within another file such as a word processor. Keep the length over 50 characters and under about 3000, which is roughly two double space typed pages. The 3500 figure allows extra for the strange things that HTML does to some punctuation characters and to line ends.
Microsoft used to run "helpful hints" in its software; a favorite was: "Don't run with scissors. You might hurt yourself." In the same vein, and assuming you have read the example above, we offer this hint: "When grating cheese, watch out for your knuckles in the grater."
Turn attention now to the small box at the bottom. Above it is an explanation of the kind of key that you may use. Key types vary according to the level of Marpx Privacy you have -- One, Two, Three, or Government. Caution: In unusual situations (flash drive full or write permission denied) there will be no explanation, but only the words "The same key must be used to recover it." If that happens, click Home, then Exit. You need to take care of that inability to write before going on.
In this Level One example, the five digits 73164 were chosen to privatize this message. It's entirely up to you what five digits you choose for any particular file or message. It's more convenient to repeat the same code as in previous encryptions, but it is less secure to repeat. That's up to you.
Click the large Encrypt Message button.
The message is instantly made into a file. The file's location and name is provided as in the above screen. The location is normally in a "MyPrivacy" directory on the same drive as your MarpX Privacy program -- on your flash drive, on a portable hard drive, or on your PC's hard disk, depending on how you installed it. The name is "Msg_" followed by a date stamp, and the suffix ".enc". Example: Msg_Sat_Sep_15_17.17.20_2018.txt.ENC" -- Notice the 24 hour clock. 17.17.20 means 20 seconds after 5:17 p.m.
Encrypted messages are wrapped in text, so that they may readily be copied and pasted to email or to social media pages. Files attached to or spread in emails easily get past unfriendly spam filters. The instructions to copy and paste are shown on the page; the steps become second nature quickly.
The first time you run the program, try some experiments.
- See if you can make any sense out of the jumble of letters, digits, periods, and exclamation marks that make up an encrypted message. Bet you can't! If you can, you deserve a high paying job with the U.S. National Security Agency.
- If you have a Facebook page, write a message for friends. Copy and paste the message into your Facebook page, and phone a couple of friends to tell them the key you used. Ask them to go to the Decrypt Msg page in their copies of MarpX Privacy, highlight, copy and paste your Facebook message and enter your key. They will get the message. Mark Zuckerberg and Facebook will not get it.
- As an experiment, write a message, then highlight and copy it as in the box above. Then click on the Decrypt Msg button at the bottom of the page. More on this experiment below.
Let's assume you have highlighted a text-like segment including the <<< and >>> anchors, and you have used CTRL-C to copy it onto the Microsoft "clipboard". The large box on the Decrypt Message page is the place to take it. Click anywhere in the big box, click CTRL-V. It will look like this:
Enter the same code that was used to encrypt it. Click on Decrypt Message.
Decrypted messages are turned into files. Here is the file name and where it is located. Notice the name ... same as the incoming message, except the .enc suffix has been removed, and the suffix is now ".decrypted.txt". The word ".decrypted" is added so that it does not overwrite the original message, and you can compare the two if you wish.
When you decrypt a message, you are shown the plain text, that is, the original message. (If there were any accented characters or special characters in the message, this step is skipped. But the full message is still in the file named above.)
There is a Home key at the bottom of the page. Click on that, then choose Encrypt File.
Files are even easier to make private. So long as the file is somewhere between 50 bytes and 100,000,000 bytes, this version of MarpX Privacy will handle it. (Need something that does gigabyte size files? Contact us.)
Simply browse and select the file you want to make private. Then input below whatever key you want to use this time. The screen will look like this:
Click Encrypt This File and you will be shown...
... the location and name of the encrypted file. The name is the same as the input file, but with a file extension .enc added at the end.
You are NOT shown the encrypted file. It's a mess, an absolute jumble of all 256 different characters that can be contained in a computer byte. If you are really interested in what's in an encrypted file, skip by the graceful exit offered to non-techies below, and work your way to the very end of this page.
For now, click the Home button below and continue this tour by choosing Decrypt File.
Normally you would park the encrypted file in archives or send it to someone else. For this tour, let's simply decrypt the same file that was encrypted above. Browse to H:\MyPrivacy and select assignment7.pdf.enc. Input the same key, 54109. Click Decrypt File.
As always, you are shown the location and name of the result. Typically it is found in the MyPrivacy directory. The .enc file extension is gone and the word ".decrypted" appears before the current extension. In this case, it is a PDF (Portable Document Format) file.
In this example, it's a PDF file...
Here it is, opened with Adobe Acrobat:
Going back to the original file and opening that, it looks exactly the same. In reality, it more than looks the same. It IS the same. More on that below. Prove it to yourself with a file that you encrypt and then decrypt.
DOS spells out sizes to the exact byte count. Assignment7.pdf from the example above is 1,425,184 bytes.
The encrypted version, assignment.pdf.enc, is 771,414 bytes (a 46 percent saving in archive space). The decrypted file assignment7.decrypted.pdf is exactly the same size as the original -- 1,425,184 bytes.
fc stands for "file compare"; it's a standard DOS program for comparing files. It shows that the original and the later decrypted files are identical.
Bytes is a tiny Marpex Inc. utility program to assess the distribution of bytes in any file whatsoever. The /d argument tells the program to assemble a list of the frequencies, percent occurence, and first eight positions of each byte value from 0 through 255.
Here's the top of the list...
and a section in the middle...
and the end of the list. Inspection of the entire list shows every byte value making up 0.4 percent of the file.
The frequencies are very tightly grouped. The mean frequency is 3013. The standard deviation indicates that 95 percent of the frequencies lie between 2905 and 3197 (minus or plus 188). In other words, the distribution is exceptionally even. There is no accepted standard measure of randomness of a file, but nearly even distribution like this suggests there is little in the way of patterns remaining within the encrypted file. Our little "pattern pulverizers" have done their job well.
ByteSeq is another Marpex Inc. utility that takes the time to look for every recurrence of any four byte pattern within a file. In the 771,414 bytes in assignment.pdf.enc, the ByteSeq program looked at each of the 771,411 four byte patterns, and counted instances in which a pattern occurred at least three times. That's a lot of work, but the program is efficient; it took four seconds. Its finding:
No patterns, never an instance in which any pattern occured more that twice. This is typical of MarpX Privacy encrypted files in this size range. Larger files may show very occasional instances of four byte patterns; that's all.
One more way of looking at patterns -- a byte dump. Here is a sample chosen at an arbitrary starting point within assignment.pdf.enc.
The 8 digits to the left are the offset. 16 bytes are shown in hexadecimal on each line, repeated to the right with printable characters showing and binary bytes shown as periods. No matter where you try within an encrypted file, this is the kind of meaningless patternless distribution you will see.
What's the point of all this? A patternless file leaves a hacker without clues on how to trim the steps required to apply a brute force technique to decipher a file made private using MarpX Privacy.