ALL the CTFS of Crypto2025 finally

crypto-asimmetric/RSA-6/attack.py

@@ -0,0 +1,22 @@
+from Cryptodome.Util.number import bytes_to_long, getPrime, inverse
+from pwn import *
+HOST = "130.192.5.212"
+PORT = "6646"
+e = 65537
+sleepT = 0.1
+server = remote(HOST,PORT)
+
+c = server.recv(1024).strip()
+sleep(sleepT)
+p = b'e4\n'
+server.send(p)
+sleep(sleepT)
+pe = server.recv(1024).strip()
+
+server.send(b'd')
+server.send(str(int(pe)*int(c)))
+server.send(b'\n')
+sleep(sleepT)
+d = int(server.recv(1024))
+print(bytearray.fromhex(format(d // 4, "x")).decode())
+#m = (pow(4, e, n) * c) % n

crypto-asimmetric/RSA-6/chall.py

@@ -0,0 +1,19 @@
+from Cryptodome.Util.number import bytes_to_long, getPrime, inverse
+from secret import flag
+
+p, q = getPrime(512), getPrime(512)
+n = p*q
+e = 65537
+m = bytes_to_long(flag.encode())
+print(pow(m, e, n))
+
+for _ in range(3):
+    req = input()
+    if req[0] == 'e':
+        print(pow(int(req[1:]), e, n))
+    elif req[0] == 'd':
+        phi = (p-1)*(q-1)
+        d = inverse(e, phi)
+        dec = pow(int(req[1:]), d, n)
+        assert dec != m
+        print(dec)