1337UP LIVE CTF 2023
Encoding [50 pts]
Challenge Description:
I have no idea what this message means, can you help me decipher it? 👨💻
enc.txt
We’re given a ciphertext
EUZEKJJSIUSTERJFGJCSKMSFEUZDAJJSIUSTERJFGJCSKMSEEUZEIJJSGASTERJFGJCSKMSFEUZEKJJSIUSTEMBFGJCSKMSFEUZEKJJSIUSTERJFGIYCKMSFEUZEKJJSIUSTERBFGJCCKMRQEUZEKJJSIUSTERJFGJCSKMSFEUZDAJJSIUSTERJFGJCSKMSFEUZEKJJSGASTERJFGJCSKMSFEUZEKJJSIUSTEMBFGJCSKMSFEUZEKJJSIUSTERJFGIYCKMSFEUZEKJJSIUSTERBFGJCCKMRQEUZEKJJSIUSTERJFGJCSKMSFEUZDAJJSIUSTERJFGJCSKMSFEUZEKJJSGASTERBFGJCSKMSFEUZEKJJSIUSTEMBFGJCSKMSFEUZEKJJSIUSTERBFGIYCKMSFEUZEKJJSIUSTERJFGJCSKMRQEUZEKJJSIUSTERJFGJCCKMSEEUZDAJJSIUSTERJFGJCSKMSFEUZEKJJSGASTERJFGJCSKMSFEUZEIJJSIQSTEMBFGJCSKMSFEUZEKJJSIUSTERJFGIYCKMSEEUZEKJJSIUSTERJFGJCSKMRQEUZEKJJSIUSTERJFGJCSKMSFEUZDAJJSIUSTERJFGJCCKMSEEUZEIJJSGASTERJFGJCSKMSFEUZEKJJSIQSTEMBFGJCSKMSEEUZDAJJSIQSTERJFGJCSKMSFEUZEKJJSGASTERJFGJCSKMSFEUZEKJJSIUSTEMBFGJCCKMSEEUZEKJJSIUSTERJFGIYCKMSFEUZEIJJSGASTERBFGJCSKMSFEUZEKJJSIUSTEMBFGJCSKMSFEUZEKJJSIUSTERBFGIYCKMSEEUZEKJJSIUSTERJFGJCSKMRQEUZEKJJSIUSTERBFGJCSKMRQEUZEKJJSIUSTERJFGJCSKMSEEUZDAJJSIUSTEMBFGJCSKMSFEUZEKJJSIUSTERBFGIYCKMSFEUZEKJJSIUSTERJFGJCCKMRQEUZEIJJSIUSTERJFGJCSKMSFEUZDAJJSIUSTERJFGJCSKMSFEUZEIJJSGASTERBFGJCSKMSFEUZEKJJSIUSTEMBFGJCCKMSFEUZEKJJSIUSTERJFGIYCKMSEEUZEKJJSIUSTERJFGJCSKMRQEUZEKJJSIUSTERJFGJCSKMSEEUZDAJJSIQSTERBFGJCSKMSFEUZEKJJSGASTERJFGJCCKMRQEUZEKJJSIUSTERJFGJCSKMSFEUZDAJJSIUSTERBFGJCCKMSEEUZEIJJSGASTERJFGJCSKMSFEUZEIJJSIQSTEMBFGJCSKMSEEUZEIJJSIQSTERBFGIYCKMSFEUZEKJJSIUSTERJFGJCSKMRQEUZEIJJSIQSTERBFGJCSKMSFEUZDAJJSIQSTERBFGJCSKMSFEUZEKJJSGASTERJFGJCCKMRQEUZEKJJSIUSTERJFGJCSKMSEEUZDAJJSIQSTERJFGJCSKMRQEUZEKJJSIUSTERJFGJCCKMSEEUZDAJJSIQSTERBFGJCCKMSEEUZEIJJSGASTERJFGJCSKMSFEUZEKJJSIQSTEMBFGJCSKMRQEUZEKJJSIUSTERJFGJCSKMSFEUZDAJJSIQSTERBFGJCCKMSFEUZEKJJSGASTERBFGJCSKMSFEUZEKJJSIUSTEMBFGJCCKMSFEUZEIJJSIUSTEMBFGJCCKMSFEUZEKJJSIUSTERJFGIYCKMSEEUZEKJJSIUSTERJFGJCSKMRQEUZEIJJSIUSTERJFGJCSKMSFEUZDAJJSIUSTERJFGJCSKMSEEUZEIJJSGASTERBFGJCSKMSFEUZEKJJSIUSTEMBFGJCSKMSEEUZDAJJSIUSTERJFGJCSKMSFEUZEIJJSGASTERJFGJCSKMSFEUZEKJJSIUSTEMBFGJCSKMSFEUZEKJJSIQSTERBFGIYCKMSFEUZEKJJSIQSTERBFGJCCKMRQEUZEIJJSIUSTERJFGJCSKMSFEUZDAJJSIUSTERBFGJCCKMSEEUZEIJJSGASTERJFGJCSKMSFEUZEKJJSIQSTEMBFGJCSKMSFEUZEKJJSIUSTERBFGIYCKMSEEUZEKJJSIUSTERJFGJCSKMRQEUZEKJJSIUSTERJFGJCCKMSEEUZDAJJSIUSTERJFGJCCKMSEEUZEIJJSGASTERJFGJCSKMSEEUZEKJJSGASTERBFGJCSKMSFEUZEKJJSIUSTEMBFGJCCKMSFEUZEKJJSIUSTERJFGIYCKMSFEUZEKJJSIUSTERJFGJCSKMRQEUZEKJJSIQSTERBFGJCCKMSEEUZDAJJSIUSTERJFGJCSKMSEEUZEIJJSGASTERBFGJCSKMSFEUZDAJJSIUSTERJFGJCSKMSEEUZEIJJSGASTERBFGJCSKMSF
This contains all uppercase letters, and none of the usual suspects (Caesar’s, monoalphabetic substitution, etc.) seem to be working.
Additionally, this is hinted by the problem name to be an encoding. Maybe it’s base 32?
Base32 decoding returns this string:
%2E%2E%2E%2E%2E%20%2E%2E%2E%2D%2D%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2D%2D%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2D%2D%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2E%2E%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2E%2D%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2D%2D%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2D%2D%20%2E%2E%2E%2E%2E%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2E%2E%20%2E%2E%2D%2D%2D%20%2E%2E%2E%2E%2D%20%2E%2D%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2E%2E%20%2D%2D%2E%2E%2E%20%2E%2D%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2E%2D%20%2D%2E%2E%2E%2E%20%2E%2E%2D%2E%20%2E%2E%2E%2E%2D%20%2E%20%2E%2E%2E%2E%2D%20%2E%2E%2E%2E%2D%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2E%2D%20%2D%2E%2E%2E%2E%20%2D%2E%2E%2E%2E%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2E%2D%20%2D%2D%2E%2E%2E%20%2E%2D%20%2E%2E%2E%2E%2E%20%2E%2D%2D%2D%2D%20%2E%2E%2E%2D%2D%20%2E%2D%2D%2D%2D%20%2E%2E%2E%2E%2E%20%2D%2D%2D%2E%2E%20%2D%2D%2E%2E%2E%20%2E%2D%20%2E%2E%2E%2E%2D%20%2D%2E%2E%20%2E%2E%2E%2D%2D%20%2D%2D%2D%2D%2D%20%2E%2E%2E%2E%2D%20%2E%20%2E%2E%2E%2E%2E%20%2D%2D%2D%2E%2E%20%2D%2E%2E%2E%2E%20%2D%2E%2D%2E%20%2D%2E%2E%2E%2E%20%2D%2E%2E%2E%2E%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2D%2D%20%2D%2E%2E%2E%2E%20%2E%2D%20%2E%2E%2E%2E%2D%20%2E%2E%2E%2E%2E%20%2E%2E%2E%2D%2D%20%2E%2E%2D%2D%2D%20%2D%2E%2E%2E%2E%20%2E%2D%2D%2D%2D%20%2E%2E%2E%2E%2D%20%2E%2E%2E%2E%2D%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2D%2D%20%2E%2E%2D%2D%2D%20%2E%2E%2D%2E%20%2D%2E%2E%2E%2E%20%2D%2E%2E%2E%2E%20%2E%2E%2E%2E%2E%20%2E%2D%2D%2D%2D%20%2E%2E%2E%2D%2D%20%2D%2E%2E%20%2E%2E%2E%2D%2D%20%2D%2E%2E
This seems to be a string of URL-encoded characters. URL decoding returns Morse code!
..... ...-- ..... ..... ...-- ..... ..... ..... ..... ...-- ..... ..... -.... ....- ..... ...-- ..... ...-- ..... -.... ..... ..--- ....- .- -.... ..... --... .- -.... ....- -.... ..-. ....- . ....- ....- -.... ....- -.... -.... -.... ....- --... .- ..... .---- ...-- .---- ..... ---.. --... .- ....- -.. ...-- ----- ....- . ..... ---.. -.... -.-. -.... -.... -.... ...-- -.... .- ....- ..... ...-- ..--- -.... .---- ....- ....- -.... ...-- ..--- ..-. -.... -.... ..... .---- ...-- -.. ...-- -..
Putting it into a Morse code translator returns the following:
53553555535564535356524A657A646F4E446466647A5131587A4D304E586C66636A45326144632F66513D3D
This is just a hex encoded string. Hex decode it to get a base64 string:
SU5USUdSSVRJezdoNDdfdzQ1XzM0NXlfcjE2aDc/fQ==
Base64 decode that to get the flag!
INTIGRITI{7h47_w45_345y_r16h7?}