incomplete

clouds/clouds.py

@@ -0,0 +1,108 @@
+#!python2.7
+import binascii
+
+ROUNDS = 5
+BLOCK_LEN = 8
+HEX_BLOCK_LEN = BLOCK_LEN * 2
+MAX_NOTES = 2048
+MAX_NOTE_LEN = 512
+
+
+def pad(p):
+	if len(p) % BLOCK_LEN != 0:
+		return p + "\0" * (BLOCK_LEN - (len(p) % BLOCK_LEN))
+	else:
+		return p
+
+def g(i):
+	b = bin(i).lstrip("0b").rstrip("L").rjust(BLOCK_LEN * 8, "0")
+	return int(b[::-1], 2)
+
+def encrypt_block(b):
+	k = open("./key").read().rstrip()
+	assert (len(b) * ROUNDS) == len(k)
+	result = int(binascii.hexlify(b), 16)
+	for i in range(ROUNDS):
+		key = int(binascii.hexlify(k[i * BLOCK_LEN:(i + 1) * BLOCK_LEN]), 16)
+		key_odd = key | 1
+		result ^= key
+		result = g(result)
+		result = (result * key_odd) % (1 << 64)
+	return hex(result).lstrip("0x").rstrip("L").rjust(HEX_BLOCK_LEN, "0")
+
+def encrypt(msg):
+	plain = pad(msg)
+	result = ""
+	for i in range(0, len(plain), BLOCK_LEN):
+		result += encrypt_block(plain[i:i + BLOCK_LEN])
+	return result
+
+def menu(n):
+	notes = n
+	print("""
+1) Store
+2) Retrieve
+Anything else to quit
+""")
+	ui = raw_input("Selection? ").rstrip()
+	if ui == "1":
+		if len(notes) >= MAX_NOTES:
+			print("Max capacity")
+			return notes
+		ui = raw_input("Give me a note to encrypt: ").rstrip()
+		try:
+			msg = binascii.unhexlify(ui)
+		except:
+			print("Invalid input.")
+			return notes
+		if len(msg) > MAX_NOTE_LEN:
+			print("Invalid input.")
+		else:
+			notes.append(encrypt(msg))
+	elif ui == "2":
+		ui = raw_input("What index would you like to read? ").rstrip()
+		try:
+			index = int(ui)
+		except:
+			print("Invalid index.")
+			return notes
+		if index >= 0 and index < len(notes):
+			print(notes[index])
+		else:
+			print("Invalid index.")
+	else:
+		return None
+	return notes
+
+
+art = """
+		      .
+
+		      |
+	     .               /
+	      \       I
+			  /
+		\  ,g88R_
+		  d888(`  ).                   _
+	 -  --==  888(     ).=--           .+(`  )`.
+	)         Y8P(       '`.          :(   .    )
+		.+(`(      .   )     .--  `.  (    ) )
+	       ((    (..__.:'-'   .=(   )   ` _`  ) )
+	`.     `(       ) )       (   .  )     (   )  ._
+	  )      ` __.:'   )     (   (   ))     `-'.:(`  )
+	)  )  ( )       --'       `- __.'         :(      ))
+	.-'  (_.'          .')                    `(    )  ))
+			  (_  )                     ` __.:'
+
+	--..,___.--,--'`,---..-.--+--.,,-,,..._.--..-._.-a:f--.
+
+"""
+
+print(art)
+print("I love cloud watching, so I made a place to store all my notes about them.")
+
+flag = open("./flag").read().rstrip()
+notes = [encrypt(flag)]
+notes = menu(notes)
+while notes:
+	notes = menu(notes)

clouds/flag

@@ -0,0 +1 @@
+picoCTF{flagFLAG}

clouds/key

@@ -0,0 +1 @@
+12345678abcdefgh1a2b3c4d5e6f7g8hffffffff

clouds/sol.py

@@ -0,0 +1,40 @@
+#!python3
+from sage.all import *
+from pwn import *
+
+conn = remote("mercury.picoctf.net", 24402)
+conn.recvuntil(b"? ")
+
+def store(msg):
+    conn.sendline(b"1")
+    conn.recvuntil(b": ")
+    conn.sendline(msg)
+    conn.recvuntil(b"? ")
+
+def retrieve(i):
+    conn.sendline(b"2")
+    conn.recvuntil(b"? ")
+    conn.sendline(str(i).encode())
+    msg = conn.recvline().strip()
+    conn.recvuntil(b"? ")
+    return msg
+
+def sbox(input):
+    output = Integer("".join(reversed(input.binary())))
+    return output
+
+def sbox_inv(output):
+    pass
+
+def mixin_pre(input, key):
+    pass
+
+def mixin_pre_inv(output, result):
+    pass
+
+def mixin_post(input, key):
+    pass
+
+def mixin_post_inv(output, result):
+    pass
+