some starter code

chals/crypto/diagonal/challenge.yml

@@ -20,6 +20,7 @@ flags:
   - sigpwny{mult1d1m3n510n4l}
 files:
   - public.py
+  - starter.py
 hints:
   - Play with some matrices, see how the exponent affects the entries, get some equations going
 state: hidden

chals/crypto/diagonal/server.py

@@ -1,8 +1,11 @@
 import numpy as np
+import signal
+import time
 import random
 
 FLAG = "sigpwny{mult1d1m3n510n4l}"
 
+
 def inputs():
     print("[D] Define a 3 x 3 Integer Matrix M")
     M = [
@@ -18,9 +21,21 @@ def inputs():
                 return None
     return M
 
+def handler(signum, frame):
+    raise Exception("[D] Matrix Mult took too long, try something simple")
+
 def fun(M_, d):
     M = np.matrix(M_, dtype='object')
-    M = M**d
+
+    signal.signal(signal.SIGALRM, handler)
+    signal.alarm(5) # raise alarm after 5 seconds
+    try:
+        M = M**d
+    except:
+        print("[D] Matrix Mult took too long, try something simple")
+        return None
+
+    signal.alarm(0) # disable the alarm
 
     # [\\\]
     # [ \\]
@@ -37,6 +52,9 @@ def main():
         return
 
     res = fun(M, secret)
+    if res == None:
+        print("[D] You tried something weird...")
+        return
     print()
     print(f"[D] Have fun: {res}")
     print()

chals/crypto/diagonal/sol.py

@@ -1,18 +1,40 @@
+from pwn import *
 import sympy as sp
 
 def main():
 
-    res = 18669237451167230340
+    conn = remote("chal.cryptoctf.sigpwny.com", 5001)
+
+    conn.recvline() # [D] Welcome
+    conn.recvline() # [D] Define a 3 x 3 Integer Matrix M
+
+    # Send matrix
+    conn.sendline(b'1')
+    conn.sendline(b'1')
+    conn.sendline(b'1')
+    conn.sendline(b'0')
+    conn.sendline(b'1')
+    conn.sendline(b'1')
+    conn.sendline(b'0')
+    conn.sendline(b'0')
+    conn.sendline(b'1')
+
+    conn.recvline()
+    # Here is number the server gives
+    res = int(conn.recvline().decode("utf-8")[13:].strip())
+    conn.recvline()
+    print(f"Challenge Accepted: {res}")
 
     # Some solutions
-    disc = (25 - 4 * (6 - 2*int(res)))**(0.5)
-    sec_ = (-5 + disc) // 2
-    print(int(sec_))
+    # TODO: Put some writing in here
+    # disc = (25 - 4 * (6 - 2*int(res)))**(0.5)
+    # secret = (-5 + disc) // 2
 
     n = sp.Symbol('n')
-    print(sp.solve(3 + 2*n + (n**2 + n) / 2 - res, n)[1])
-
+    secret = sp.solve(3 + 2*n + (n**2 + n) / 2 - res, n)[1]
 
+    conn.sendline(str(int(secret)).encode())            # Send answer
+    print(conn.recvline().decode("utf-8")[22:].strip()) # Print flag
 
 if __name__ == "__main__":
     main()

chals/crypto/diagonal/starter.py

@@ -0,0 +1,53 @@
+from pwn import *
+
+def main():
+
+    # Here is some starter code for those unfamiliar with pwntools
+    # I am not good at pwntools, so there may be better ways to do this
+    # But this is how I know how to do things
+
+    # Connect to remote server
+    conn = remote("chal.cryptoctf.sigpwny.com", 5001)
+
+    conn.recvline() # [D] Welcome
+    conn.recvline() # [D] Define a 3 x 3 Integer Matrix M
+
+    # Send matrix here
+    # Replace the 0/1's with the numbers you want
+    conn.sendline(b'1')
+    conn.sendline(b'0')
+    conn.sendline(b'0')
+    conn.sendline(b'0')
+    conn.sendline(b'1')
+    conn.sendline(b'0')
+    conn.sendline(b'0')
+    conn.sendline(b'0')
+    conn.sendline(b'1')
+
+    conn.recvline()
+    # Here is number the server gives
+    res = int(conn.recvline().decode("utf-8")[13:].strip())
+    print(f"Challenge Accepted: {res}")
+
+
+    # TODO: Write some code to recover the secret from res!
+    #
+    # Bytes:
+    #   pwntools reads and sends bytes
+    #   .encode turns a string into a bytestring
+    #   .decode("utf-8") turns a bytestring into a string
+    #
+    # Sending and Receiving:
+    #   conn.sendline(b'#')
+    #   output = conn.recvline()
+    #   These do what you think
+    #
+    # Some basic string manipulation such as .strip() and slicing helps
+    # Use alot of print statements in debugging this
+    # Try some stuff locally as well
+    # Have a working local solution *before* pwntools-ifying it
+    #
+    # pwntools is really useful, I recommend you learn it
+
+if __name__ == "__main__":
+    main()