How to send secret messages hidden in pictures and music

Mod­ern man has thou­sands of ways to trans­mit infor­ma­tion in the blink of an eye to any­where in the world. We end­less­ly broad­cast videos, send emails and exchange var­i­ous files.

True, you have to pay for com­fort. Nev­er before have peo­ple’s per­son­al data been as vul­ner­a­ble as it is today. When send­ing a mes­sage or for­ward­ing a file, you can­not be sure that some­one else will not look into it. But at least you can try to min­i­mize the risk.

One good way to do this is to hide valu­able infor­ma­tion where no one would think to look. For exam­ple, inside a pic­ture or a musi­cal com­po­si­tion.

Encryp­tion or mask­ing?

When it comes to secu­ri­ty, many experts rec­om­mend sim­ply encrypt­ing files or trans­fer­ring them over secure chan­nels. For exam­ple, many mod­ern mes­sen­gers have an end-to-end encryp­tion func­tion. The trans­mit­ted data in this case is avail­able only to the sender and recip­i­ent. No third par­ties have access to the infor­ma­tion.

Alas, with all the reli­a­bil­i­ty of such encryp­tion, the method has no “fool­proof” pro­tec­tion. If attack­ers inter­cept the trans­mit­ted infor­ma­tion, they will not be able to decrypt it. But if they can hack direct­ly into the sender or recip­i­ent, they will see every­thing in full view.

In this sense, “mask­ing” infor­ma­tion seems to be a more reli­able method. Even if you are hacked, it is unlike­ly that the hack­er will guess that the cat pic­ture you sent con­tained a hid­den mes­sage.

How it works?

In short, part of one file is embed­ded inside anoth­er. This does not change the basic struc­ture of the sec­ond file, so it can still be used as intend­ed. If you embed some­thing in an image, that image can be opened in an edi­tor or view­er. If you embed some­thing in a music track, that track can be lis­tened to. The only thing that will change is the size of the con­tain­er file. It will become larg­er by the size of the attach­ment file. Keep this in mind when cre­at­ing a dis­guise. A small pic­ture weigh­ing sev­er­al tens of megabytes looks sus­pi­cious.

If you intend to use this method to com­mu­ni­cate with anoth­er user, the recip­i­ent must be warned in advance that you will be send­ing him mes­sages in dis­guise. More­over, this should be report­ed through anoth­er infor­ma­tion chan­nel. Best of all — in per­son. If you send a pic­ture with a hid­den mes­sage by e‑mail, and in the same let­ter reveal the secret of the attach­ment, the whole con­spir­a­cy goes to dust.

Soft­ware solu­tions

You don’t have to be a hack­er to cre­ate masked files. There are sev­er­al very sim­ple ways to nest one file with­in anoth­er. For starters, you can use ready-made pro­grams.

Quick­Stego

One of the solu­tions is a free pro­gram Quick­Stego for Win­dows. She can cre­ate BMP images with embed­ded text. You just need to press the but­tonOpen Image” to select the orig­i­nal pho­to. The text in the right field can be entered man­u­al­ly, or you can spec­i­fy a text file by click­ing the “Open Text”. After spec­i­fy­ing the desired pho­to and text, you need to click the “Hide Text” to merge the files. And then — “Save Image” to save the result­ing file in BMP for­mat.

The result­ing draw­ing can be viewed and mod­i­fied in edi­tors. The text will remain untouched. To see it, you need to open the pic­ture through the Quick­Stego pro­gram. The text will be vis­i­ble in the right mar­gin.

Deep­Sound

Anoth­er option is a free pro­gram Deep­Sound for Win­dows. It allows you to hide not only texts, but any files in gen­er­al, using music tracks as con­tain­ers. It works very sim­ply. But­ton “Open car­ri­er files” opens music files where you want to hide some­thing, or in which some­thing is already hid­den. But­ton “Add secret files” allows you to select the files you want to hide. Please note that the size of attach­ments is lim­it­ed and depends on the size of the music con­tain­er file and on the sound qual­i­ty of the out­put. The longer the audio track and the low­er the sound qual­i­ty, the more files fit inside it. But­ton “Encode secret files” is used to sew the select­ed attach­ments into the con­tain­er file. But­ton “Extract secret files” — to extract attach­ments from a pre­pared con­tain­er file. In gen­er­al, every­thing is extreme­ly sim­ple.

Com­mand line

If you do not want or do not have the oppor­tu­ni­ty to use ready-made soft­ware solu­tions, you can use the com­mand line.

Win­dows

On Win­dows, you can only hide text inside pic­tures using the com­mand line. To do this, take the text file you want to hide (here­inafter — secret.txt) and the pic­ture you want to use as a con­tain­er (here­inafter — container.jpg). Put both files in the same fold­er. Click on the address bar in the fold­er and type “cmd“ (with­out quotes). A com­mand line win­dow will appear.

In the com­mand prompt win­dow, with­out quotes, enter the fol­low­ing con­struc­tion: “copy /b secret.txt + container.jpg hidden.jpg”. Here secret.txt — the file with the text you want to hide, container.jpg — the pic­ture you want to use, and hidden.jpg — name for the new final file with the secret. File hidden.jpg will appear in the same fold­er. It will look and work like a copy container.jpgbut if you open it through Notepad or any oth­er text edi­tor, you will see your hid­den text at the very begin­ning of the doc­u­ment.

macOS

On macOS, you can hide text files or entire zip archives inside pic­tures. First, put the files you need on your desk­top. We will call the archive with secret infor­ma­tion secret.zipthe image that will serve as the con­tain­er — container.jpg.

Next, you need to launch the Ter­mi­nal appli­ca­tion (anal­o­gous to the com­mand line in macOS). To do this, acti­vate the Spot­light search with the key­board short­cut Cmd+Spacethen type “ter­mi­nal” with­out quotes and select the desired appli­ca­tion.

In the Ter­mi­nal win­dow, with­out quotes, type “cd desk­top” and press Enter to switch to the desk­top. Then, again, with­out quotes, enter the fol­low­ing con­struc­tion: “cat container.jpg secret.zip > hidden.jpg”. Here secret.zip and container.jpg — the orig­i­nal secret and con­tain­er files, and hidden.jpg — the final file with the secret that we are cre­at­ing.

Now if you try to open hidden.jpg in any graph­ics edi­tor, it will behave like a nor­mal pic­ture. But if in the Ter­mi­nal appli­ca­tion you enter the com­mand “unzip hidden.jpg”, the image will be unpacked like a reg­u­lar archive.

If ini­tial­ly instead of the archive you hid a plain text file TXT, then you can read its con­tents by open­ing hidden.jpg via TextE­d­it or any oth­er text edi­tor. The con­tents of the secret text file will be at the very end of the doc­u­ment.