Knowing the files you are dealing with
File Signatures
File signatures (also known as File Magic Numbers) are bytes within a file used to identify the format of the file. Generally they’re 2-4 bytes long, found at the beginning of a file.
Also use the command file to check the file type on Linux.
The file above, when opened in a Hex Editor, begins with the bytes FFD8FFE0 00104A46 494600
or in ASCII ˇÿˇ‡ JFIF where \x00 and \x10 lack symbols. JPEG/JFIF graphics file.
Metadata
Metadata is data about data. Different types of files have different metadata. The metadata on a photo could include dates, camera information, GPS location, comments, etc. For music, it could include the title, author, track number and album.
How do I find it?
One of our favorite tools is exiftool, which displays metadata for an input file, including: - File size - Dimensions (width and height) - File type - Programs used to create (e.g. Photoshop) - OS used to create (e.g. Apple)
exiftool(-k).exe [filename]
Interesting to look at url