50 lines
1.4 KiB
Python
50 lines
1.4 KiB
Python
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from cStringIO import StringIO
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flag = "wh3n_y0u_h4ve_p&q_RSA_iz_ez"
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def modx(base,exp,mod):
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r = 1;
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while (exp > 0):
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if (exp % 2 == 1):
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r = (r * base) % mod
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base = (base * base) % mod
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exp = exp/2
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return r
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def probprime(s):
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if s%2==0:
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s += 1
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smolprimes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]
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while len(set([modx(i,s-1,s) for i in smolprimes])) != 1 or modx(2,s-1,s) != 1:
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s+=2
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return(s)
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def get_problem(random):
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# add Probable Prime function later
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p = probprime(random.randint(3*10**79,4*10**79))
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q = probprime(random.randint(3*10**79,4*10**79))
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e = 3
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salt = "".join([random.choice("0123456789abcdef") for i in range(8)])
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return (p, q, e, salt)
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def generate_ciphertext(random):
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p, q, e, salt = get_problem(random)
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encoded = int(("easyctf{%s_%s}" % (flag, salt)).encode('hex'),16)
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ciphertext = 'p: '+str(p)+'\n'
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ciphertext += 'q: '+str(q)+'\n'
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ciphertext += 'e: '+str(e)+'\n'
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ciphertext += 'c: '+str(pow(encoded, e, p*q))+'\n'
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return StringIO(ciphertext)
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def generate(random):
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return dict(files={
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"ciphertext_rsa1.txt": generate_ciphertext
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})
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def grade(random, key):
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n, salt = get_problem(random)
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if key.find("%s_%s" % (flag, salt)) >= 0:
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return True, "Correct!"
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return False, "Nope."
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