ALL the CTFS of Crypto2025 finally

crypto-simmetric/long-secret-message/attack.py

@@ -0,0 +1,211 @@
+#!/usr/bin/env python3
+import numpy
+from string import *
+with open("./hacker-manifesto.enc") as f:
+    lines = f.readlines()
+
+for i in range(len(lines)):
+    lines[i] = bytes.fromhex(lines[i])
+
+#shortest_line = min(lines,key=len)
+#min_len = len(shortest_line)
+longest_line = max(lines, key=len)
+max_len = len(longest_line)
+candidates_list = []
+
+CHARACTER_FREQ = {
+    'a': 0.0651738, 'b': 0.0124248, 'c': 0.0217339, 'd': 0.0349835, 'e': 0.1041442, 'f': 0.0197881, 'g': 0.0158610,
+    'h': 0.0492888, 'i': 0.0558094, 'j': 0.0009033, 'k': 0.0050529, 'l': 0.0331490, 'm': 0.0202124, 'n': 0.0564513,
+    'o': 0.0596302, 'p': 0.0137645, 'q': 0.0008606, 'r': 0.0497563, 's': 0.0515760, 't': 0.0729357, 'u': 0.0225134,
+    'v': 0.0082903, 'w': 0.0171272, 'x': 0.0013692, 'y': 0.0145984, 'z': 0.0007836, ' ': 0.1918182
+} # ','
+
+for byte_to_guess in range(max_len):
+    #print(f"Byte num:{byte_to_guess}")
+    counters = numpy.zeros(256,dtype=float)
+    for guessed_byte in range(256):
+        for line in lines:
+            #print(f"Now line: {line}")
+            #line = bytes.fromhex(line)
+            if byte_to_guess >= len(line):
+                continue
+            if chr(line[byte_to_guess] ^ guessed_byte) in printable:
+                counters[guessed_byte] += CHARACTER_FREQ.get(chr(line[byte_to_guess] ^ guessed_byte).lower(),0)
+
+    max_match = max(counters)
+
+    match_list = [(counters[i],i) for i in range(256)]
+    ordered_match_list=sorted(match_list, reverse=True)
+
+    candidates = []
+    #for pair in ordered_match_list:
+    #    if pair[0] < max_match * .95:
+    #        break
+    #    candidates.append(pair)
+
+    candidates_list.append(ordered_match_list)
+
+keystream = bytearray()
+for x in candidates_list:
+    keystream += x[0][1].to_bytes(1,byteorder='big')
+
+
+from Cryptodome.Util.strxor import strxor
+
+dec = keystream[0] ^ lines[0][0]
+mask = dec ^ ord('T')
+keystream[0] = keystream[0] ^ mask
+
+dec1 = keystream[1] ^ lines[0][1]
+mask = dec1 ^ ord('h')
+keystream[1] = keystream[1] ^ mask
+
+dec2 = keystream[2] ^ lines[0][2]
+mask = dec2 ^ ord('i')
+keystream[2] = keystream[2] ^ mask
+
+dec3 = keystream[3] ^ lines[0][3]
+mask = dec3 ^ ord('s')
+keystream[3] = keystream[3] ^ mask
+
+dec5 = keystream[5] ^ lines[0][5]
+mask = dec5 ^ ord('i')
+keystream[5] = keystream[5] ^ mask
+
+pos=28
+dec = keystream[pos] ^ lines[0][pos]
+mask = dec ^ ord('o')
+keystream[pos] = keystream[pos] ^ mask
+
+l=4
+pos=17
+dec = keystream[pos] ^ lines[4][pos]
+mask = dec ^ ord('s')
+keystream[pos] = keystream[pos] ^ mask
+
+l=4
+pos=20
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('w')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=34
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord(' ')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=36
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord(' ')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=37
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('s')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=38
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('e')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=40
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('v')
+keystream[pos] = keystream[pos] ^ mask
+
+l=2
+pos=49
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('r')
+keystream[pos] = keystream[pos] ^ mask
+
+l=2
+pos=53
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('b')
+keystream[pos] = keystream[pos] ^ mask
+
+l=2
+pos=42
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('w')
+keystream[pos] = keystream[pos] ^ mask
+
+l=2
+pos=43
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('a')
+keystream[pos] = keystream[pos] ^ mask
+
+l=2
+pos=45
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('n')
+keystream[pos] = keystream[pos] ^ mask
+
+l=0
+pos=46
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('o')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=57
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('t')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=58
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('i')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=59
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('n')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=64
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('t')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=65
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('h')
+keystream[pos] = keystream[pos] ^ mask
+
+l=1
+pos=67
+dec = keystream[pos] ^ lines[l][pos]
+mask = dec ^ ord('u')
+keystream[pos] = keystream[pos] ^ mask
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+for line in lines:
+    l = min(len(keystream),len(line))
+    print(strxor(line[:l],keystream[:l]))

crypto-simmetric/long-secret-message/chall-original.py

@@ -0,0 +1,19 @@
+import os
+from Cryptodome.Cipher import ChaCha20
+
+key = os.urandom(32)
+nonce = os.urandom(12)
+print(f"Using key: {key.hex()}, nonce: {nonce.hex()}")
+
+with open("./hacker-manifesto.txt") as f:
+    lines = f.readlines()
+#
+#hacker-manifesto.txt encrypted in enc
+enc = []
+
+for line in lines:
+    cipher = ChaCha20.new(key=key, nonce=nonce)
+    enc.append(cipher.encrypt(line.encode()).hex())
+
+with open("./hacker-manifesto.enc", "w") as f:
+    f.write("\n".join(enc))

crypto-simmetric/long-secret-message/chall.py

@@ -0,0 +1,21 @@
+import os
+from Cryptodome.Cipher import ChaCha20
+
+key = os.urandom(32)
+nonce = os.urandom(12)
+print(f"Using key: {key.hex()}, nonce: {nonce.hex()}")
+
+with open("./hacker-manifesto.txt") as f:
+    lines = f.readlines()
+#
+#hacker-manifesto.txt encrypted in enc
+enc = []
+#Maybe recreating the cipher generate the same keystream?
+# Yes it is.
+
+for line in lines:
+    cipher = ChaCha20.new(key=key, nonce=nonce)
+    enc.append(cipher.encrypt(line.encode()).hex())
+
+with open("./hacker-manifesto.enc", "w") as f:
+    f.write("\n".join(enc))

crypto-simmetric/long-secret-message/hacker-manifesto.enc

@@ -0,0 +1,8 @@
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crypto-simmetric/long-secret-message/original.enc

@@ -0,0 +1,8 @@
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