ALL the CTFS of Crypto2025 finally

crypto-asimmetric/RSA-2/attack.py

@@ -0,0 +1,56 @@
+from Cryptodome.Util.number import bytes_to_long
+from Cryptodome.Util.number import isPrime
+from Cryptodome.Util.number import getPrime
+from Cryptodome.Util.number import getRandomInteger
+
+from gmpy2 import next_prime
+from gmpy2 import isqrt
+# p = getPrime(512)
+# q = next_prime(p)
+# n = p*q
+# c = print(pow(m, e, n))
+def egcd(a, b):
+    if (a == 0):
+        return (b, 0, 1)
+    else:
+        g, y, x = egcd(b%a, a)
+        return (g, x - (b//a) * y, y)
+
+e = 65537
+n = 60509355275518728792864353034381323203712352065221533863094540755630035742080855136016830887120470658395455751858380183285852786807229077435165810022519265154399424311072791755790585544921699474779996198610853766677088209156457859301755313246598035577293799853256065979074343370064111263698164125580000165237
+c = 44695558076372490838321125335259117268430036823123326565653896322404966549742986308988778274388721345811255801305658387179978736924822440382730114598169989281210266972874387657989210875921956705640740514819089546339431934001119998309992280196600672180116219966257003764871670107271245284636072817194316693323
+
+
+
+a = b = isqrt(n)
+b2 = pow(a,2) - n
+
+i = 0
+
+while True:
+    print("Iteration # ="+str(i))
+    if b2 == pow(b,2):
+        print("solution found")
+        break
+    else:
+        a+=1
+        b2 = pow(a,2) - n
+        b = isqrt(b2)
+        print("a = " + str(a))
+        print("b = " + str(b))
+        print("b2 = " + str(b2))
+        print("delta-->"+str(pow(b,2)-b2 % n))
+        i+=1
+    p = a+b
+    q = a-b
+
+    print(f"P={p}")
+    print(f"Q={q}")
+
+phi = (p-1)*(q-1)
+res = egcd(e, phi)
+u = res[1]
+
+decrypted = pow(c,u,n)
+
+print(decrypted.to_bytes(decrypted.bit_length()//8+1,byteorder='big').decode())

crypto-asimmetric/RSA-2/chall.py

@@ -0,0 +1,20 @@
+from Cryptodome.Util.number import bytes_to_long, getPrime, isPrime
+from secret import flag
+
+
+def next_prime(p):
+    while True:
+        p = p+1
+        if isPrime(p):
+            return p
+
+#Close numbers so n = pq = (a^2 - b^2)
+p = getPrime(512)
+q = next_prime(p)
+n = p*q
+e = 65537
+print(n)
+m = bytes_to_long(flag.encode())
+print(pow(m, e, n))
+# Output: 6050935527551872879286435303438132320371235206522153386309454075563003574208085513601683088712047065839545575185838018328585278680722907743516581002251926515439942431107279175579058554492169947477999619861085376667708820915645785930175531324659803557729379985325606597907434337006411126369816412558000016523744695558076372490838321125335259117268430036823123326565653896322404966549742986308988778274388721345811255801305658387179978736924822440382730114598169989281210266972874387657989210875921956705640740514819089546339431934001119998309992280196600672180116219966257003764871670107271245284636072817194316693323
+#