How to send secret messages hidden in pictures and songs

In this information age, we can transfer video streams, emails and files to all over the world in seconds. While this makes information sharing extremely convenient, you can never be fully confident about what will happen to 1s and 0s sent to digital space.

If you want to make sure that only your contacts, not others, can see the data you send, you need to hide it in another file. This is actually very simple. Here is how to hide sensitive information in a more concealed way.

Encrypt and hidden files

When it comes to protecting your private information, many experts recommend that you encrypt your files. In this way of sending data securely, a secure messaging application like Signal or WhatsApp will do the heavy lifting for you, encrypting your message content so that no one except the intended recipient can read it they. If others try to intercept encrypted communications—which could be from hackers eavesdropping on a free Wi-Fi connection in your coffee shop to internet service providers that view your activity—they will only see meaningless mixes of codes . It is difficult to convert these messages into readable forms.

But encryption is not foolproof. If someone knows your email or message app password, or accesses your unlocked phone or computer, they can view your encrypted file like the original recipient. That's why you might want to add another layer of security: hide private files in other files.

Working principle

So, what actually happens when you hide one file in another? Essentially, you add the code for the first snippet—its actual 1s and 0s—to the second file, which can be an image, an audio clip, or anything else. The change occurs in a way that does not affect the content of the carrier (although this increases its size), which means you can still open the envelope file and use it as usual.

This allows the vector file to be hidden in a conspicuous place. If someone should visit your machine and come across a photo folder, they can view the picture without knowing that the picture contains other files. (Of course, in an ideal world, this person won't get into your computer first. We recommend that you use hidden file security methods in conjunction with other measures, such as choosing a secure password for your Windows or macOS account.)

When you are ready to send hidden files to friends, they need to notify in advance: You need to tell the recipient of newly packaged data that you are hiding part of the digital information in another part of the information. Ideally, you would explain this in a way of communication and then send the file itself through different channels. For example, you can tell your contacts what they need to know via phone or face-to-face meeting, and then send the file through the Messages app.

Simple Program

Now that you know how this technology works, you need some software to help with this task. There are several different ways you can take to hide files, but all the tools we will discuss work similarly. And to use them, you don’t need to be a coding guru—or have any technical knowledge.

QuickStego is a free solution for Windows users. It places any text file into a bitmap image (BMP) file. First, you and the file recipient need to install QuickStego. Then, use the Open Image and Open Text buttons to combine your image and text. When you try to open the generated image in any other program, it will appear as a normal bitmap image, but when you open it with QuickStego you will see the image and text.

Another Windows-only program is DeepSound, which hides most common file types, including PDFs and images, in audio files. The song can still be played in a normal audio program, but when the receiver opens it in DeepSound, they can extract hidden information. The interface is also simple: just click to open the carrier file to select your audio container, and click to add a secret file to select the file you want to hide.

Type command

If you don't want to rely on either of these two programs—or you're using a macOS machine, it doesn't have as many good software options—you can hide the file by typing commands. On Windows, you can do this via a command prompt, and on macOS, you can open a terminal window. Either way, this process doesn't feel particularly laborious or technical, although you need to type carefully.

In Windows, you can only hide text files in images. Put the file you are about to hide (we call it "secret.txt") and your container file ("picture.jpg") into the same folder and in File Explorer Open this folder. Click the address bar (the path to the folder), type "cmd", and press Enter. A command prompt window will appear. In it, type "copy /b secret.txt picture.jpg hidden.jpg" and press Enter. (Of course, you will use the file name of the text you want to hide instead of "secret.txt", and you should replace "picture.jpg" with the file name of the image you want to use as the container. You can use whatever you want Replace "hidden.jpg" with the name of the new file you want to create. And don't forget the two spaces before the final file name.) The newly created file appears as a normal image when it opens in the image editor, but if you're noting it Open it in this or other text editor and you can see hidden text at the top of the page.

On macOS, you can package a single text file or zip file (an archive of any type of file) into an image. First, move the relevant files to the desktop. Similarly, we call the container image "picture.jpg" and the hidden file "secret.txt", although in this case it can also be easily called "secret.zip". Then start the terminal application (open Spotlight with Cmd Space, type "terminal", and select the correct application when it appears). In Terminal, type "cd desktop" and press Enter to switch to the desktop. Next, type "cat picture.jpg secret.txt > hidden.jpg" and press Enter. Like Windows, we call the finished image "hidden.jpg", but you can change the file name to whatever name you like. When you open it in any image editing program, it looks like a normal picture; when you open it in an application like TextEdit, the hidden text appears at the end. If you have the archive hidden, the hidden files are retrieved slightly differently: Go back to the terminal, type "unzip hidden.jpg" (or any file name you choose), and press Enter. The hidden files will then be scattered onto the desktop again.

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