ctf_aria

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soal

Well done. You’ve moved past an easy substitution cipher.
The main weakness of a simple substitution cipher is repeated use of a simple key. In the previous exercise you were able to introduce arbitrary plaintext to expose the key. In this example, the cipher mechanism is not available to you, the attacker.

However, you have been lucky. You have intercepted more than one message. The password to the next level is found in the file ‘krypton4’. You have also found 3 other files. (found1, found2, found3)

You know the following important details:
The message plaintexts are in American English (* very important) - They were produced from the same key (* even better!) Enjoy.

ssh

sshpass -p "CAESARISEASY" ssh -o StrictHostKeyChecking=no krypton3@krypton.labs.overthewire.org -p 2231

# scp
sshpass -p "CAESARISEASY" scp -R -P 2231 krypton3@krypton.labs.overthewire.org:/krypton/krypton3/* krypton3

solve

cd /krypton/krypton3
ls
# found1  found2  found3  HINT1  HINT2  krypton4  README

cat HINT1
# Some letters are more prevalent in English than others.

cat HINT2
# "Frequency Analysis" is your friend.

cat krypton4 
# KSVVW BGSJD SVSIS VXBMN YQUUK BNWCU ANMJS

jika terdapat kata kata frequency analysis bisa jadi iniadalah subsitusi cipher
terdapat beberapa tool untuk subsitusi cipher salah satunya yaitu
sebelum kita mencoba mencari tau pola krypton4 kita perlu mencari pola dengan beberapa teks pada found1 - found3 karena semakin banyak teks nya semakin mudah untuk mendapatkan pola

solve with tool

solve with manual (cli) (belum berhasil)

git clone https://github.com/m-rosinsky/Krypton_Scripts
cp Krypton_Scripts/freq_analysis.py .

python3 freq_analysis.py found1 1
# S:      155
# C:      107
# Q:      106

python3 freq_analysis.py found1 3
# JDS:    19
# DSN:    11
# QGW:    11

for i in {A..Z}; do cat found1 found2 found3 | tr -cd $i | wc -c | tr -d '\n'; printf " $i\n" ; done | sort -nr
# 456 S
# 340 Q
# 301 J
# 257 U
# 246 B
# 240 N
# 227 G
# 227 C
# 210 D
# 132 Z
# 130 V
# 129 W
# 86 M
# 84 Y
# 75 T
# 71 X
# 67 K
# 64 E
# 60 L
# 55 A
# 28 F
# 19 I
# 12 O
# 4 R
# 4 H
# 2 P

# Freq list: ETAOINSRHDLUCMFYWGPBVKXQJZ
# Cipher text: SQJUBNGCDZVWMYTXKELAFIORHP

cat krypton4 | tr [“JDS”] [“the”] # because freq 3 let ke 1

KeVVW BGeth eVeIe VXBMN YQUUK BNWCU ANMte

cat krypton4 | tr [“JDSQB”] [“theao”] # karena Q freq 1 let ke 2, B karena dia juga aioeo (fokus ke aiueo dulu)

KeVVW oGeth eVeIe VXoMN YaUUK oNWCU ANMte

cat krypton4 | tr [“JDSQBKVI”] [“theaowlv”]

wellW oGeth eleve lXoMN YaUUw oNWCU ANMte

cat krypton4 tr [“JDSQBKVIWG”] [“theaowlvdes”]

KeVVW BGe the VeIe VXBMN YQUUK BNWCU ANMte KeVVW oGe the leIe lXoMN YaUUK oNWAU ANMte

cat krypton4 tr [“JDSQB”] [“theao”]

KeVVW oGe the leIe lXoMN YaUUK oNWAU ANMte well WoGe the level XoMN YaUUK oNWAU ANMte

tr [“JDSQBKVI”] [“THEAOWLV”]

well WoGe the level XoMN YaUUK oNWAU ANMte well done the level XoMN YaUUW oNWAU ANMte

tr [“JDSQBKVIWG”] [“THEAOWLVDN”]

well done the level XoMr passK oNWAU ANMte

tr [“JDSQBKVIWEUYR”] [“THEAOWLVDESPR”]

well done the level XoMr passK oNWAU ANMte well done the level four password AUANMte

tr [“JDSQBKVIWEUYRXMK”] [“THEAOWLVDESPRFUW”]

OGETH ELEVE LFOUN PASSW ONDCS ANUTE


- https://www3.nd.edu/~busiforc/handouts/cryptography/cryptography%20hints.html
```bash
E T A O I N S H R D L U

manual (gagal)

for i in {A..Z}; do printf $i; done
# ABCDEFGHIJKLMNOPQRSTUVWXYZ

for i in {A..Z}; do printf $i; cat found1 found2 found3; done
ACGZNL YJBEN QYDLQ ZQSUQ NZCYD SNQVU BFGBK GQUQZ QSUQN UZCYD SNJDS UDCXJ ZCYDS NZQSU QNUZB WSBNZ QSUQN UDCXJ CUBGS BXJDS UCTYV SUJQG WTBUJ KCWSV LFGBK GSGZN LYJCB GJSZD GCHMS UCJCU QJLYS BXUMA UJCJM JCBGZ CYDSN CGKDC ZDSQZ DVSJJ SNCGJ DSYVQ CGJSO JCUNS YVQZS WALQV SJJSN UBTSX COSWG MTASN BXYBU CJCBG UWBKG JDSQV YDQAS JXBNS OQTYV SKCJD QUDCX JBXQK BMVWA SNSYV QZSWA LWAKB MVWAS ZBTSS QGWUB BGJDS TSJDB WCUGQ TSWQX JSNRM VCMUZ QSUQN KDBMU SWCJJ BZBTT MGCZQ JSKCJ DDCUE SGSNQ VUJDS SGZNL YJCBG UJSYY SNXBN TSWAL QZQSU QNZCY DSNCU BXJSG CGZBN YBNQJ SWQUY QNJBX TBNSZ BTYVS OUZDS TSUU ....

for i in {A..Z}; do printf $i; cat found1 found2 found3 | tr -cd $i; done
#AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCCCCCCCC

for i in {A..Z}; do printf $i; cat found1 found2 found3 | tr -cd $i| wc -c; done
A55 # A 55
B246 # B 246
---

for i in {A..Z}; do printf $i; cat found1 found2 found3 | tr -cd $i| wc -c | tr -d "\n"; done
# A55B246C227D210E64F28G227H4I19J301K67L60M86N240O12P2Q340R4S456T75U257V130W129X71Y84Z132

## remove first variable $i and add in the last
for i in {A..Z}; do cat found1 found2 found3 | tr -cd $i | wc -c | tr -d "\n"; printf " $i \n"; done | sort -nr
456 S
340 Q
301 J
257 U
246 B
240 N
227 G
227 C
210 D
132 Z
130 V
129 W
86 M
84 Y
75 T
71 X
67 K
64 E
60 L
55 A
28 F
19 I
12 O
4 R
4 H
2 P

- dan karena S adalah kata yang sering muncul
- asumsikan bahwa s adalahh huruf e karena e adalah kata yang sering muncul dalam bahasa inggris
- disini saya mencoba dengan list ini dan berharap teksnya benar
  - https://www3.nd.edu/~busiforc/handouts/cryptography/cryptography%20hints.html
    ```bash
    E T A O I N S H R D L U
    ```

cat krypton4 | tr "SQJUBNGCDZVWMYTXKELAFIORHP" "ETAOINSHRDLU"

bash shell looping (test)

## iterasi semua output dan menyamakan dengan $i
for i in {a..z}; do echo "aria fatah anom" | tr -cd $i; done # aria fatah anom => aaaaaf...
# aaaaafhimnort

## iterasi dengan taambahan wc c yang digunakan untuk menghitung byte
for i in {a..z}; do printf $i; echo "aria fatah anom" | tr -cd $i | wc -c; done && echo
a5 # a terdapat 5
---
# ketika printf $i maka dia akan juga manampilkan abcde..z dengan tambahan masing masing iterasi

echo "aria_fatah" | tr -d _ # delete _ string
# ariafatah

echo "aria_fatah" | tr -cd aria # compleate delete only show teks a, r, i
# ariaaa

flag

BRUTE