The SCRYPTO (Steganographic CRYPTOgraphy) Protocol is a toy protocol I designed for secure communication on computer networks. It makes use of covert channels in the TCP protocol to steganographically transfer encrypted information.
Steganography is the art of information hiding, while cryptography is more like information scrambling. Covert channels such as slack space in network data structures are prime candidates for covert transfer of data.
I was in high-school when I wrote this. Hilariously, I implemented 3-DES and Diffie-Hellman key exchange by hand (which is a terrible idea). For some reason I was very intent on doing a “clean room” implementation using only the standard (for academic integrity :P) so I did it without looking at any other implementations. I verified it against the against the test-cases provided in the FIPS specification.