Added writeups for Crypto (Whitehacks2022)

ThinkerPal · Mar 27, 2022 · 6090b5a · 6090b5a
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diff --git a/2022-01-Whitehacks/Crypto/Really S1mpl3 Algorithm/README.md b/2022-01-Whitehacks/Crypto/Really S1mpl3 Algorithm/README.md
@@ -1,21 +1,46 @@
-# [Challenge]
+# Really S1mp(l3) Algorithm
 
 - Category: Crypto
-- Points: ?/? (If there is Point Decay, stating the original score would help)
-- Captures: [] (Mainly as a means of the relative difficulty of the flag)
-- Challenge Helpers: [Insert anyone else here who helped]
-
+- Points: 135/1000
+- Captures: 72
 ## Challenge Description:
-[Challenge Description]
+Rumour has it that this algorithm originated from the Republic of South Africa!
 
 ## Files Attached:
-[If any, list them here - paste source code but link binaries]
-
+[challenge.txt](challenge.txt)
 ## Solution:
 
-### Tools used:
-- [Tools]
+### Tools that would have been helpful:
+- [factordb.com](factordb.com)
+
+Taking a look at the file, we see 4 variables `p`, `q`, `e` and `ct` defined, and further taking inspiration from the initals of this challenge, we can infer that this challenge has to deal with RSA (and decrypting the ciphertext).
+
+With some quick googling, I found [this page](https://www.amazingtricks.in/how-to-solve-rsa-crypto-challenges-in-ctfs/) and its accompanying code to decrypt our ciphertext. Since in our case the components of the prime `p` and `q` have been given to us, we do not need to factorsie anything (which the site recommeneded [factordb](factordb.com) for.)
+
+A quick edit to the code later, we end up with this:
+
+```python
+#!/usr/bin/python3
+from Crypto.Util.number import inverse
+p = 89677525768054651799811339393073439598902155753884683756875620558829954902529
+
+q = 84438062750417241222463359000671279258755386034358736244893269480285225711041
+
+e = 65537
+
+ct = 2006481391032768131106572837821981606814991526844317992631122301790966354846642917808142106585149537517169168108747108233658443914026685951141453359021205
+
+phi = (p-1)*(q-1)
+d=inverse(e, phi)
+m=pow(ct,d,p*q)
+print(hex(m)[2:-1])
+```
+
+Running the program after that gives us a hexadecimal string, which we can then throw into [CyberChef](gchq.github.io/CyberChef) to convert to our flag.
 
-[Actual Solution goes here]
+(Note: I did realise when runnning the python program that there was a little bit of a weird ending to the flag – I'm pretty sure that if I bothered to look at the code more I could have fixed it, but in my case I just removed the trailing period with a closing curly brace)
 
-## Flag:
+## Flag:
+```
+WH2022{1t5_r34lly_s1mpl3_4m_1_r1ght}
+```
diff --git a/2022-01-Whitehacks/Crypto/Really S1mpl3 Algorithm/challenge.txt b/2022-01-Whitehacks/Crypto/Really S1mpl3 Algorithm/challenge.txt
@@ -0,0 +1,9 @@
+This is really simple. I hope you can solve it.
+
+p = 89677525768054651799811339393073439598902155753884683756875620558829954902529
+
+q = 84438062750417241222463359000671279258755386034358736244893269480285225711041
+
+e = 65537
+
+ct = 2006481391032768131106572837821981606814991526844317992631122301790966354846642917808142106585149537517169168108747108233658443914026685951141453359021205
diff --git a/2022-01-Whitehacks/Crypto/Ridiculously Simpler Algorithm/README.md b/2022-01-Whitehacks/Crypto/Ridiculously Simpler Algorithm/README.md
@@ -1,21 +1,21 @@
-# [Challenge]
+# Ridiculously Simpler Algorithm 
 
 - Category: Crypto
-- Points: ?/? (If there is Point Decay, stating the original score would help)
-- Captures: [] (Mainly as a means of the relative difficulty of the flag)
-- Challenge Helpers: [Insert anyone else here who helped]
+- Points: 976/1000 
+- Captures: 14
 
 ## Challenge Description:
-[Challenge Description]
+You cracked me once, now I'm back for revenge with an upgraded defence mechanism!
 
 ## Files Attached:
-[If any, list them here - paste source code but link binaries]
+[ecrypted.txt](encrypted.txt)
 
 ## Solution:
 
 ### Tools used:
 - [Tools]
 
-[Actual Solution goes here]
+Looked up the key in factordb, seemed like it was a square number, but couldn't figure out how to move on from there. may try again later
 
-## Flag:
+## Flag:
+no solve
diff --git a/2022-01-Whitehacks/Crypto/Ridiculously Simpler Algorithm/encrypted.txt b/2022-01-Whitehacks/Crypto/Ridiculously Simpler Algorithm/encrypted.txt
@@ -0,0 +1,7 @@
+This is supposedly even simpler. Try me!
+
+n = 10737815683051749791647908968171036410193052055925978453198599402338822997173859289423308183048750681303695147135467822832842221572174477705930888427996441
+
+e = 65537
+
+c = 2025103500488147486354827835413388045219955669590787897403050967001645770151549545526845887271487454606326620556228871888382889102118986522714812376848980
diff --git a/2022-01-Whitehacks/Crypto/The Indecipherable Cipher/README.md b/2022-01-Whitehacks/Crypto/The Indecipherable Cipher/README.md
@@ -1,21 +1,37 @@
-# [Challenge]
+# The Indecipherable Cipher 
 
 - Category: Crypto
-- Points: ?/? (If there is Point Decay, stating the original score would help)
-- Captures: [] (Mainly as a means of the relative difficulty of the flag)
-- Challenge Helpers: [Insert anyone else here who helped]
+- Points: 441/1000
+- Captures: 55
 
 ## Challenge Description:
-[Challenge Description]
+Some say this cipher cannot be deciphered. Well, do you believe them?
+
+Even worse, some say this cipher is misattributed!
+
+I would say that the key to solving this challenge is to remember who the true inventor was.
 
 ## Files Attached:
-[If any, list them here - paste source code but link binaries]
+[cipher.txt](cipher.txt)
 
 ## Solution:
 
 ### Tools used:
-- [Tools]
+- [CyberChef](gchq.github.io/CyberChef)
+
+Having a look at the cipher text, we can see that the general structure of the flag was still there, but it has obviously been jumbled. Since the challenge description mentioned that `the key to solving this challenge is to remember was the true inventor was`, I guessed that the cipher used was a [vigenere cipher](https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher).
+
+A quick look at the Wikipedia page (which is the source of Truth™) tells us that this cipher was invented by one "Giovan Battista Bellaso"
+
+So I tried their full name! But it didn't work... not completely
+
+![](wrongkey.png)
+
+So, I tried just using their first name, "Giovan", which resulted in success!
 
-[Actual Solution goes here]
+![](rightkey.png)
 
-## Flag:
+## Flag:
+```
+WH2022{v1g3n3r3_15_Juz_Ca3s@r_C1pH3R_0N_sT3R01Ds}
+```
diff --git a/2022-01-Whitehacks/Crypto/The Indecipherable Cipher/cipher.txt b/2022-01-Whitehacks/Crypto/The Indecipherable Cipher/cipher.txt
@@ -0,0 +1 @@
+CP2022{j1b3n3e3_15_Pcn_Xa3f@x_K1dC3R_0A_yB3F01Ys}
diff --git a/2022-01-Whitehacks/Crypto/The Indecipherable Cipher/rightkey.png b/2022-01-Whitehacks/Crypto/The Indecipherable Cipher/rightkey.png
diff --git a/2022-01-Whitehacks/Crypto/The Indecipherable Cipher/wrongkey.png b/2022-01-Whitehacks/Crypto/The Indecipherable Cipher/wrongkey.png
diff --git a/2022-01-Whitehacks/Crypto/The Poem of Knowledge/Poem Of Knowledge.txt b/2022-01-Whitehacks/Crypto/The Poem of Knowledge/Poem Of Knowledge.txt
@@ -0,0 +1,26 @@
+The Road Not Taken
+By Robert Frost
+
+Two roads diverged in a yellow wood,
+And sorry I could not travel both
+And be one traveler, long I stood
+And looked down one as far as I could
+To where it bent in the undergrowth;
+
+Then took the other, as just as fair,
+And having perhaps the better claim,
+Because it was grassy and wanted wear;
+Though as for that the passing there
+Had worn them really about the same,
+
+And both that morning equally lay
+In leaves no step had trodden black.
+Oh, I kept the first for another day!
+Yet knowing how way leads on to way,
+I doubted if I should ever come back.
+
+I shall be telling this with a sigh
+Somewhere ages and ages hence:
+Two roads diverged in a wood, and I—
+I took the one less traveled by,
+And that has made all the difference.
diff --git a/2022-01-Whitehacks/Crypto/The Poem of Knowledge/README.md b/2022-01-Whitehacks/Crypto/The Poem of Knowledge/README.md
@@ -1,21 +1,30 @@
-# [Challenge]
+# The Poem of Knowledge 
 
 - Category: Crypto
-- Points: ?/? (If there is Point Decay, stating the original score would help)
-- Captures: [] (Mainly as a means of the relative difficulty of the flag)
-- Challenge Helpers: [Insert anyone else here who helped]
+- Points: 767/1000
+- Captures: 40
+- Challenge Helpers: @oneytlam
 
 ## Challenge Description:
-[Challenge Description]
+Our knowledgeable alien friend named Beale left us with a purported "Poem of Knowledge" before he went back to his universe.
+
+He also dropped a message behind. Can you decipher what he was trying to say?
+
+17-73-24-55-84-101-141-44-54-49-10-123-62-131-114-67-47-46-60-83-84
+
+Note: Please wrap the flag with WH2022{...}\u003cbr\u003e\nThe flag is case-sensitive!
 
 ## Files Attached:
-[If any, list them here - paste source code but link binaries]
+[Poem of Knowledge](Poem%20of%20Knowledge.txt)
 
 ## Solution:
+Will get to it soon™
 
+My teammate was the one who kinda figured this out, but by the time we did so the time was already out :(
 ### Tools used:
 - [Tools]
 
 [Actual Solution goes here]
 
-## Flag:
+## Flag: 
+no solve
diff --git a/2022-01-Whitehacks/README.md b/2022-01-Whitehacks/README.md
@@ -14,11 +14,10 @@
 
 ## Flags:
 ### Crypto:
-- [Really S1mp(l3) Algorithm](Crypto/Really%20S1mpl3%20Algorithm/) (Incomplete)
-- [The Indecipherable Cipher](Crypto/The%20Indecipherable%20Cipher/) (Incomplete)
-- [Ridiculously Simpler Algorithm](Crypto/Ridiculously%20Simpler%20Algorithm/) (Incomplete)
-- [The Poem of Knowledge](Crypto/The%20Poem%20of%20Knowledge/) (Incomplete)
-
+- [Really S1mp(l3) Algorithm](Crypto/Really%20S1mpl3%20Algorithm/) 
+- [The Indecipherable Cipher](Crypto/The%20Indecipherable%20Cipher/) 
+- [Ridiculously Simpler Algorithm](Crypto/Ridiculously%20Simpler%20Algorithm/) (Did not manage to complete during CTF, may try again later)
+- [The Poem of Knowledge](Crypto/The%20Poem%20of%20Knowledge/) (Did not manage to complete during CTF, may try again later)
 ### Forensics:
 - [The Prompt Within](Forensics/The%20Prompt%20Within/) (Incomplete)
 - [Jack's Rival](Forensics/Jacks%20Rival/) (Incomplete)
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		@@ -0,0 +1 @@
		CP2022{j1b3n3e3_15_Pcn_Xa3f@x_K1dC3R_0A_yB3F01Ys}