题目

crypto/easy_pow/easy_pow.py

@@ -0,0 +1,67 @@
+from hashlib import sha256
+import socketserver
+import signal
+import string
+import random
+import os
+
+
+class Task(socketserver.BaseRequestHandler):
+    def _recvall(self):
+        BUFF_SIZE = 2048
+        data = b''
+        while True:
+            part = self.request.recv(BUFF_SIZE)
+            data += part
+            if len(part) < BUFF_SIZE:
+                break
+        return data.strip()
+
+    def send(self, msg, newline=True):
+        try:
+            if newline:
+                msg += b'\n'
+            self.request.sendall(msg)
+        except:
+            pass
+
+    def recv(self, prompt=b'[-] '):
+        self.send(prompt, newline=False)
+        return self._recvall()
+
+    def proof_of_work(self):
+        random.seed(os.urandom(8))
+        proof = ''.join(
+            [random.choice(string.ascii_letters+string.digits) for _ in range(20)])
+        _hexdigest = sha256(proof.encode()).hexdigest()
+        self.send(f"[+] sha256(XXXX+{proof[4:]}) == {_hexdigest}".encode())
+        x = self.recv(prompt=b'[+] Plz tell me XXXX: ')
+        if len(x) != 4 or sha256(x+proof[4:].encode()).hexdigest() != _hexdigest:
+            return False
+        return True
+
+    def handle(self):
+        signal.alarm(60)
+        if not self.proof_of_work():
+            self.send(b'[!] Wrong!')
+            return
+
+        self.send(b'here is your flag')
+        self.send(flag)
+
+
+class ThreadedServer(socketserver.ThreadingMixIn, socketserver.TCPServer):
+    pass
+
+
+class ForkedServer(socketserver.ForkingMixIn, socketserver.TCPServer):
+    pass
+
+
+if __name__ == "__main__":
+    flag = bytes(os.getenv("FLAG"),"utf-8")
+    HOST, PORT = '0.0.0.0', 10001
+    server = ForkedServer((HOST, PORT), Task)
+    server.allow_reuse_address = True
+    print(HOST, PORT)
+    server.serve_forever()