hivnZX9h

1require "inline"
2require "prime"
3
4class RSA
5  class << self
6    def generate
7      p, q = generate_unique_primes
8      n = p * q
9      e = (p - 1) * (q - 1) - 1
10      d = generate_secret_key(e, (p - 1) * (q - 1))
11      puts "Public Key: '#{n}:#{e}'"
12      puts "Secret Key: '#{d}'" # TODO 1: eとdの値が一緒になってしまう
13    end
14
15    def encrypt(message, public_key)
16      m = message # TODO 2: 文字列を数値に変換できるようにする
17      n = public_key.split(":").first.to_i
18      e = public_key.split(":").last.to_i
19      puts "Code: '#{(m ** e) % n}'"
20      # TODO 3: 数が大きいとべき乗で warning: in a**b, b may be too big のエラーが出る
21    end
22
23    def decrypt(code, public_key, secret_key)
24      c = code
25      n = public_key.split(":").first.to_i
26      d = secret_key.to_i
27      puts "Message: '#{(c ** d) % n}'"
28    end
29
30    private
31
32    def generate_unique_primes
33      p, q = 0, 0
34      loop do
35        p = Random.new.rand(100...1000)
36        break if p.prime?
37      end
38      loop do
39        q = Random.new.rand(100...1000)
40        break if q.prime? && p != q
41      end
42      [p, q]
43    end
44
45    def generate_secret_key(e, _i)
46      # TODO 4: 秘密鍵生成のもっとスマートなやりかたがあるはず
47      ::GenerateSecretKey.new.execute(e, _i)
48    end
49  end
50end
51
52class GenerateSecretKey
53  inline do |builder|
54    builder.include "<math.h>"
55    builder.c %q{
56      long execute(long e, long _i) {
57        long d = 0;
58        while (d * e % _i != 1 % _i) { d++; }
59        return d;
60      }
61    }
62  end
63end