hsf/ma5/rsa/rsa.rb

module RSA
	def self.n_inv(a, m)
		(1..m).each{|x| break x if (a*x % m == 1)}
	end

	class Key
		def initialize(p1, p2)
			puts "Generating key pair..."
			@n = p1 * p2
			@phi = (p1-1)*(p2-1)

			enc = []
			(2...@phi).each do |e|
				dom = e.gcd(@phi)

				if dom == 1 then
					enc << e
				end
			end
			@e = enc.sample

			@d = RSA.n_inv(@e, @n)
			puts "e=#{@e} d=#{@d}"
		end

		def pubkey
			return @e, @n
		end

		def privkey
			return @d, @n
		end
	end

	class Data 
		attr_reader :data
		def initialize(data)
			@data = data
			if data.is_a? String then
				@data = @data.split("").map do |c|
					c.ord.to_i
				end
			end
			puts "Generated bytearray: #{@data}"
		end

		def raw
			str = ""
			@data.each do |byte|
				str += "\\x#{byte.to_s 16}"
			end
			return str
		end

		def inspect(endchar="\n")
			pattern = "c" * @data.length
			return "# \'#{@data.pack(pattern)}\'#{endchar}"
		end

		def encrypt(pubkey)
			e, n = pubkey
			crypt = []	
			@data.each do |c|
				cr = (c ** e) % n
				crypt << cr
			end

			return crypt 
		end

		def decrypt(privkey)
			d, n = privkey 
			crypt = []	
			@data.each do |c|
				cr = (c ** d) % n
				crypt << cr
			end

			return crypt 
		end

		def encrypt!(pubkey)
			@data = self.encrypt(pubkey)
		end

		def decrypt!(privkey)
			@data = self.decrypt(privkey)
		end
	end
end