US Cyber Command Valentine’s Day Cryptography Puzzles
The US Cyber Command has released a series of ten Valentine’s Day “Cryptography Challenge Puzzles.”
Slashdot thread. Reddit thread. (And here’s the archived link, in case Cyber Command takes the page down.)
Tatütata • February 15, 2021 3:40 PM
Nice to see that there are people with some time to spare…
These puzzles are rather unusual and tech oriented, as opposed to crossword or sudoku paper problems.
The audio puzzles are interesting.
In puzzle 2, the information (amplitude, phase) is very different on either channel, much more than on a typical stereo recording. The pulsed nature of the music suggests the use of amplitude for coding, especially considering that the scheme would have to survive the MP3 coding.
For puzzle 3, my hunch is that the message is coded in the hushing and barking sound in the background, possibly using Morse code.
In puzzle 7, I found the use of a BMP format quite unusual for 2021, probably a 24 bit RGB file without transparency (TBC). The small image size (20×20) is also somewhat strange in comparison with the other pictures. A PNG file would have done it just as well, so I had a look at the guts of the with an hex editor, I discovered a rather long text apparently coded in one of the RGB colour channels the Red channel (“[This person] can see SHA-256 collisions by holding a hash up to a mirror…”, etc.), and the two other RGB colour channels seem to hold the information, as it contains apparently only 0x00 and 0xff bytes.
Puzzle 9 could be some sort of rébus. Is that one of the Queen’s Corgi’s?