ALL the CTFS of Crypto2025 finally

crypto-asimmetric/RSA-8/attack.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+def iroot(k, n):
+    u, s = n, n+1
+    while u < s:
+        s = u
+        t = (k-1) * s + n // pow(s, k-1)
+        u = t // k
+    return s
+
+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)
+
+n = [103182582101088432221896723911959658810148642607491933315730960734118240195754769950819474607526761310491072435697251726703164265174774235724659738831757409760766157639161825762332534066038346404165315092057708788440973076257965331599855954578010994574159603470755148099351579202141225172980367799665476167847, 164529226839413559924976053055945999494164079991436306473401181675696469337231336487085545789574002739916229214459538703141568506814456513212890362327970644104020403940185072579976632642454837002305793830295185819162025725080875039582271289438064337645037739930310804010164136027800069917885200489266709851147, 101253463082304765569988541878936444188901784404118982304304492412707865403599337342671466935573442997065056100597392285699618123881764488797053967545477164493257618640769155601013044416777930811645230707542352289749878326865162201600174774219905814876248581859055603923729383992948817570153516220675788026019]
+c = [49061847403090198347871622684419440435020583765472679724043086578999237521080306057376530837215217884164240970675343921488615718206622981851071355344619510984897988244448903079728468570182192877366774485494180463301223638383404084085162769928604900840343104637519232149881136672689624849105790343296894169638, 69379335482793180476700701606108054426491112911094839088423398496436178476703250112662999759680953829050820926826348692673810360008347808961160090296815470631238301541316949142095598699542200662648425136888777434584579800116810012163027021559640993590961230761590447340796858130209448565431799660026498031809, 12703169327460384687002396982277926563609859240682417397412251404704813340279611932445729764372467798958975417752028956581609966062236180984581318736509577950218952687259759058038887912101360016831759532164596689952106890923630907107502607383301971789208757053392565264776050015020366373713225575559221036110]
+
+n1 = n[0]
+n2 = n[1]
+n3 = n[2]
+
+c1 = c[0]
+c2 = c[1]
+c3 = c[2]
+
+g, u1,v1 = egcd(n2*n3, n1)
+g, u2,v2 = egcd(n1*n3, n2)
+g, u3,v3 = egcd(n1*n2, n3)
+
+c = (c1 * u1 * n2*n3 + c2 * u2* n1*n3 + c3 * u3 * n1*n2) % (n1*n2*n3)
+e = 3
+dec_int = iroot(e, c)
+print(dec_int.to_bytes(dec_int.bit_length()//8 + 1, byteorder='big').decode())

crypto-asimmetric/RSA-8/chall.py

@@ -0,0 +1,11 @@
+from Crypto.Util.number import bytes_to_long, getPrime
+from secret import flag
+
+n1 = getPrime(512)*getPrime(512)
+n2 = getPrime(512)*getPrime(512)
+n3 = getPrime(512)*getPrime(512)
+n = [n1, n2, n3]
+print(n)
+e = 3
+m = bytes_to_long(flag.encode())
+print([pow(m, e, nn) for nn in n])