There are many ways to encrypt a message in an image file.
The way I've seen people do this on YouTube is them just editing
the image's hex coding.
Anyway, it depends on how the message is encrypted. If it is
just regular text in the image, you have to get a hex editor, such
as Hex Workshop, then load the image and parse the hex coding to
find the message.
In most cases, it will be located in the first few lines of the
hex coding and it will be just a regular string, unencrypted.
In more advanced cases I've seen, it could be located near the
middle of the whole hex coding of the image, then encoded again
using a method called "Base64". To decrypt this message, I had to
open up the hex coding, find the Base64 encoded string (usually
ends with two equal signs "=="), then I had to unencrypt the Base64
string, which is really easy. In PHP, it's just a simple
command:
echo base64_decode("base64string");
?>
Once I unencrypted the base64 string, it output the hidden
message.
Conclusion:
Just open the image up in Hex Workshop, and read a few lines of
the hex coding. Usually the message can be found in the first few
lines.
