Fixed dumb stuff

ma5/rsa/rsa.rb

@@ -1,13 +1,37 @@
 module RSA
-	def self.n_inv(a, m)
-		(1..m).each{|x| break x if (a*x % m == 1)}
+	def self.egcd(a, b)
+		if a == 0 then
+			return b, 0, 1
+		else
+			g, y ,x = self.egcd(b % a, a)
+			return g, x - (b.to_i / a.to_i)*y, y
+		end
+	end
+
+	def self.modinv(a, m)
+		g, x, y = self.egcd(a, m)
+		if g != 1 then
+			raise "Mod inv does not exist"
+		else
+			return x % m
+		end
 	end
 
 	class Key
+		private def find_d
+			puts "Generating private key..."
+			begin
+				return @d
+			rescue RuntimeError
+				puts "d not found, retrying..."
+				retry
+			end
+		end
+
 		def initialize(p1, p2)
 			puts "Generating key pair..."
 			@n = p1 * p2
-			@phi = (p1-1)*(p2-1)
+			@phi = (p1-1).lcm(p2-1)
 
 			enc = []
 			(2...@phi).each do |e|
@@ -18,10 +42,9 @@ module RSA
 				end
 			end
 			@e = enc.sample
-			p enc
+			@d = RSA.modinv(@e, @phi)
 
-			@d = RSA.n_inv(@e, @n)
-			puts "e=#{@e} d=#{@d}"
+			puts "e: #{@e} d: #{@d}"
 		end
 
 		def pubkey
@@ -42,7 +65,7 @@ module RSA
 					c.ord.to_i
 				end
 			end
-			puts "Generated bytearray: #{@data}"
+			puts "Generated bytes: #{self.raw}"
 		end
 
 		def raw

ma5/rsa/test.rb

@@ -1,14 +1,37 @@
 #!/usr/bin/ruby -w
-
 require_relative "rsa"
 
-Primes = File.read("primes.txt").chomp.split(",").map do |pstr|
+Primes = File.read("smallprimes.txt").chomp.split(",").map do |pstr|
 	p = pstr.to_i
 end
 
-puts "Fetching random primes..."
-p1, p2 = Primes.sample, Primes.sample
-p1, p2 = 11, 13
+def get_random_primes
+	puts "Fetching random primes..."
+	p1, p2 = Primes.sample, Primes.sample
+	return p1, p2
+end
+
+def choose_primes
+	print "1st prime: "
+	p1 = gets.chomp.to_i
+	print "2nd prime: "
+	p2 = gets.chomp.to_i
+
+	return p1, p2
+end
+
+puts "[1] Random primes"
+puts "[2] Choose primes"
+ch = gets.chomp.to_i
+case ch
+when 1
+	p1, p2 = get_random_primes
+when 2
+	p1, p2 = choose_primes
+else
+	p1, p2 = get_random_primes
+end
+
 puts "p1=#{p1}, p2=#{p2}"
 puts
 
@@ -23,5 +46,4 @@ puts "Encrypted bytes: #{data.raw}"
 
 data.decrypt!(key.privkey)
 puts "Decrypted bytes: #{data.raw}"
-p data.data