ALL the CTFS of Crypto2025 finally

crypto-asimmetric/RSA-7/attack.py

@@ -0,0 +1,35 @@
+from pwn import *
+import decimal
+
+HOST = "130.192.5.212"
+PORT = "6647"
+server = remote(HOST,PORT)
+
+n = int(server.recv(1024).strip())
+c = int(server.recv(1024).strip())
+e = 65537
+
+def to_bytes(m,l=512):
+    return int.to_bytes(m, l=n.bit_length(), byteorder='big')
+def print_bounds(low, up):
+    print("[" + str(low) + "," + str(up) + "]")
+decimal.getcontext().prec = n.bit_length()
+upper_bound = decimal.Decimal(n)
+lower_bound = decimal.Decimal(0)
+m = c
+for i in range(n.bit_length()):
+    m = (pow(2, e, n) * m) % n
+    print(f"M:{m}")
+    server.send(str(m))
+    server.send(b'\n')
+    bit = server.recv(1024)
+    bit = int(bit)
+    print(f"Bit:{bit}")
+    if  bit == 1:
+        lower_bound = (upper_bound + lower_bound) / 2
+    else:
+        upper_bound = (upper_bound + lower_bound) / 2
+#lower_bound = 158107821233229568930984452875602183391823091373912004357129417626853988321867785934374974861174017194049484884
+upper_bound = int(upper_bound)
+print(f"UB:{upper_bound}")
+print(upper_bound.to_bytes(n.bit_length(),'big').decode())