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require 'socket' |
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#http://www.scribd.com/doc/34203336/How-to-Implement-RSA-in-Ruby#download |
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# Calculate a modular exponentiation eg: b^p mod m |
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def mod_pow(base, power, mod) |
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result = 1 |
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while power > 0 |
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result = (result * base) % mod if power & 1 == 1 |
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base = (base * base) % mod |
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power >>= 1 |
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end |
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result |
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end |
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# Convert a string into a big number |
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def str_to_bignum(s) |
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n = 0 |
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s.each_byte {|b|n=n*256+b} |
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n |
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end |
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# Convert a bignum to a string |
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def bignum_to_str(n) |
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s="" |
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while n>0 |
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s = (n&0xff).chr + s |
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n >>= 8 |
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end |
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s |
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end |
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#http://rosettacode.org/wiki/Modular_inverse#Ruby |
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#based on pseudo code from http://en.wikipedia.org/wiki/Extended_Euclidean_algorithm#Iterative_method_2 and from translating the python implementation. |
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def extended_gcd(a, b) |
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last_remainder, remainder = a.abs, b.abs |
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x, last_x, y, last_y = 0, 1, 1, 0 |
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while remainder != 0 |
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last_remainder, (quotient, remainder) = remainder, last_remainder.divmod(remainder) |
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x, last_x = last_x - quotient*x, x |
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y, last_y = last_y - quotient*y, y |
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end |
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return last_remainder, last_x * (a < 0 ? -1 : 1) |
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end |
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def invmod(e, et) |
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g, x = extended_gcd(e, et) |
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if g != 1 |
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raise 'Teh maths are broken!' |
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end |
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x % et |
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end |
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#puts variable name and value |
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def debug(sym) |
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puts "#{sym} is #{eval sym.to_s, TOPLEVEL_BINDING}" |
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end |
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if ARGV.size < 2 |
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puts "usages: ruby socialist_milli.rb <ip address> <secret> <optional:your port:default 44444> <optional:their_port:default 44444>" |
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exit 1 |
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end |
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begin |
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socket = TCPSocket.new ARGV[0], ARGV[3] || 44444 |
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guy2 = true |
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rescue |
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server = TCPServer.new ARGV[2] || 44444 |
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socket = server.accept |
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guy2 = false |
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end |
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# A prime and a generator (primitive root) for that prime. |
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# Can be same as OTR: http://www.ietf.org/rfc/rfc3526.txt |
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#prime = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208552BB9ED529077096966D670C354E4ABC9804F1746C08CA237327FFFFFFFFFFFFFFFF |
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prime = 97 |
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h = 5 |
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x = str_to_bignum ARGV[1] |
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puts "your secret num is #{x}" |
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a = guy2 ? 4 : 2 |
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alpha = guy2 ? 5 : 3 |
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r = guy2 ? 6 : 9 |
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h_to_the_a = mod_pow(h,a,prime) |
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socket.puts h_to_the_a |
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h_to_the_b = socket.gets.to_i |
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g = mod_pow(h_to_the_b, a, prime) |
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debug :g |
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h_to_the_alpha = mod_pow(h,alpha,prime) |
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socket.puts h_to_the_alpha |
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h_to_the_beta = socket.gets.to_i |
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gamma = mod_pow(h_to_the_beta, alpha, prime) |
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debug :gamma |
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p = mod_pow(gamma,r,prime) |
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socket.puts p |
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q = socket.gets.to_i |
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debug :p |
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debug :q |
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t = q*invmod(p, prime) % prime |
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debug :t |
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p_prime = (mod_pow(h,r,prime)*mod_pow(h,x,prime)) % prime |
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socket.puts p_prime |
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q_prime = socket.gets.to_i |
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debug :p_prime |
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debug :q_prime |
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p_prime_q_prime_inverse_to_the_alpha = mod_pow(((p_prime*invmod(q_prime, prime)) % prime),alpha, prime) |
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socket.puts p_prime_q_prime_inverse_to_the_alpha |
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p_prime_q_prime_inverse_to_the_beta = socket.gets.to_i |
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debug :p_prime_q_prime_inverse_to_the_beta |
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c = mod_pow(p_prime_q_prime_inverse_to_the_beta,alpha,prime) |
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debug :c |
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puts c == t |
