![]() Intentionally - and knowing what you're doing. Okay, now editing text was fun already, but imagine that you're actually going to manipulate binary data! O.O If you want to replace it with a shorter text, just add "space" characters to fill it up until its "null-terminated" end. So please: If you edit text strings, stay inside their boundaries. When doing this to a media file, pixels might be ill-colored, or the whole image falls apart, or all colors are wrong - or the viewing application crashes. If it's an executable, it might crash when trying to read that string, or access the data that you deleted by replacing it with your text. If you change a text string in a binary file and you overwrite its end (=the 0x00 byte), you overwrite actual code. Otherwise, bad things may - and probably will - happen to your file and to your system." ![]() It was endless fun translating English to Austrian slang, and share this personalized version with friends :Dīut when my father showed us this "hacker tool", he advised us: Maybe I chose this, because that was the first thing I did with a hex editor when I was a kid: I changed text phrases in my favorite computer games. But let's start with editing text in binary files. The hex editor can be used to edit binary files. That's how you know where one term ends and another one begins. The metadata fields inside a PNG for example, are separated by a 0x00 character. Therefore they're called " null-terminated strings". Text strings inside a binary file often end with the hex character "0x00". If you see the text displayed with dots, use multi-byte encoding, otherwise single-byte. Now, when searching for text inside a binary file, some editors allow to specify if you search for 1 or 2 byte encoded strings. Therefore the letters between the dots :) Thanks to downwards compatiblity with single-byte ASCII mapping, the basic alphanumeric characters are still readable in their 1-byte representation. The dots between the letters in Unicode are not to indicate an abbreviation, or some ASCII-Art: The dots represent non-printable characters. Single- and multi-byte character encoding of "hello" next to each other (separated by a space character "0x20") ![]() Here's a bogus example how these 2 encodings would look in a hex editor: If it's a number, you already know what to do, but if it's text you may find 2 different ways in which its displayed in the text column: In order to read embedded metadata, you need to know at which byte offsets to find which data field and how to interpret it. If you look at a lossy compressed audio file like MP3 or MP4, it's quite likely to contain descriptive metadata embedded. Handling text in binary files Searching TextĪs already mentioned, you'll encounter text phrases inside binary files. There is also a PDF version of this document available for download, as well as its Markdown source code. This article is mainly aimed at archivists with digital preservation needs, and maybe a bit for data forensic beginners. This part is about handling the data in the file itself, such as searching or editing text or reading and editing binary data with the use of a file format specification paper. In the previous part, we've covered the basics of "what is hex?" and how to use a hex editor for binary files.
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