Problem: Here’s another simple cipher for you where we made a bunch of substitutions. Can you decrypt it? Connect with nc 2018shell.picoctf.com 43324.
Solution:
Running the command prints this to the console.
miuqxsdk yvxv wk riex zbsq - kefkdwdedwiu_mwpyvxk_sxv_kibnsfbv_xvcpzrvcmx------
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di wudvxvkd jv iu kyixv, w dyieqyd w aiebc kswb sfied s bwddbv suc kvv dyv asdvxr psxd iz dyv aixbc. wd wk s asr w ysnv iz
s csjp, cxwoobr uinvjfvx wu jr kieb; ayvuvnvx w zwuc jrkvbz wunibeudsxwbr psekwuq fvzixv mizzwu asxvyiekvk, suc fxwuqwuq e
p dyv xvsx iz vnvxr zeuvxsb w jvvd; suc vkpvmwsbbr ayvuvnvx jr yrpik qvd kemy su eppvx ysuc iz jv, dysd wd xvtewxvk s kdxiu
u, w smmieud wd ywqy dwjv di qvd di kvs sk kiiu sk w msu. dywk wk jr kefkdwdedv zix pwkdib suc fsbb. awdy s pywbikipywmsb z
biexwky msdi dyxiak ywjkvbz epiu ywk kaixc; w tewvdbr dshv di dyv kywp. dyvxv wk uidywuq kexpxwkwuq wu dywk. wz dyvr fed hu
va wd, sbjikd sbb jvu wu dyvwx cvqxvv, kijv dwjv ix idyvx, myvxwky nvxr uvsxbr dyv ksjv zvvbwuqk diasxck dyv imvsu awdy jv.
dyvxv uia wk riex wukebsx mwdr iz dyv jsuysddivk, fvbdvc xieuc fr aysxnvk sk wucwsu wkbvk fr mixsb xvvzk-mijjvxmv kexxieuck
bv wk askyvc fr asnvk, suc miibvc fr fxvvovk, aywmy s zva yiexk pxvnwiek avxv ied iz kwqyd iz bsuc. biih sd dyv mxiack iz a
sdvx-qsovxk dyvxv.
mwxmejsjfebsdv dyv mwdr iz s cxvsjr ksffsdy szdvxuiiu. qi zxij mixbvsxk yiih di mivudwvk kbwp, suc zxij dyvumv, fr aywdvysb
b, uixdyasxc. aysd ci rie kvv?-pikdvc bwhv kwbvud kvudwuvbk sbb sxieuc dyv diau, kdsuc dyieksuck epiu dyieksuck iz jixdsb j
k iz kywpk zxij mywus; kijv ywqy sbizd wu dyv xwqqwuq, sk wz kdxwnwuq di qvd s kdwbb fvddvx kvsasxc pvvp. fed dyvkv sxv sbb
bsuckjvu; iz avvh csrk pvud ep wu bsdy suc pbskdvx-dwvc di mieudvxk, uswbvc di fvumyvk, mbwumyvc di cvkhk. yia dyvu wk dyw
k? sxv dyv qxvvu zwvbck qiuv? aysd ci dyvr yvxv?
ud dyvj fed dyv vldxvjvkd bwjwd iz dyv bsuc; biwdvxwuq eucvx dyv kyscr bvv iz riucvx asxvyiekvk awbb uid kezzwmv. ui. dyvr
jekd qvd gekd sk uwqy dyv asdvx sk dyvr pikkwfbr msu awdyied zsbbwuq wu. suc dyvxv dyvr kdsuc-jwbvk iz dyvj-bvsqevk. wubsuc
v, civk dyv jsquvdwm nwxdev iz dyv uvvcbvk iz dyv mijpskkvk iz sbb dyikv kywpk sddxsmd dyvj dywdyvx? dyvr sbb euwdv. dvbb j
Using a online cipher solving, you can figure out this is a substitution cipher.
Key:
Flag: picoCTF{substitution_ciphers_are_solvable_redpfyedcr}