b00tl3grsa3

b00tl3grsa3/sol.py

@@ -0,0 +1,35 @@
+#!python3
+from sage.all import *
+import pwn
+
+conn = pwn.remote("jupiter.challenges.picoctf.org", 4557)
+
+conn.recvuntil(b"c: ")
+c = Integer(conn.recvline().strip())
+pwn.log.info("c: 0x{:x}".format(c))
+
+conn.recvuntil(b"n: ")
+n = Integer(conn.recvline().strip())
+pwn.log.info("n: 0x{:x}".format(n))
+
+conn.recvuntil(b"e: ")
+e = Integer(conn.recvline().strip())
+pwn.log.info("e: 0x{:x}".format(e))
+
+conn.close()
+
+pwn.log.info("factoring n")
+factors = factor(n)
+pwn.success("factorization: {}".format(factors))
+
+totient = prod([x[0]-1 for x in factors])
+pwn.log.info("totient: {:x}".format(totient))
+
+pwn.log.info("calculating d")
+d = pow(e, -1, totient).lift()
+pwn.log.success("d: {:x}".format(d))
+
+m = pow(c, d, n).lift()
+flag = pwn.pack(int(m), 'all', 'big', False)
+pwn.log.info("flag: {}".format(flag))
+