From bleepingcomputer.com
Generating checksums—cryptographic hashes such as MD5 or SHA-256 functions for files is hardly anything new and one of the most efficient means to ascertain the integrity of a file, or to check if two files are identical.
However, generating a file containing its own checksum as part of its content is a task quite daunting, if not seemingly impossible due to a paradox involved in the process.
That has not stopped a researcher from creating a PNG image that contains the file’s MD5 checksum, visible within the matrix of pixels that make up the image.