Ma5: RSA

ma5/rsa/brute.rb

@@ -0,0 +1,28 @@
+#!/usr/bin/ruby -w
+
+require_relative "rsa.rb"
+# pubkey : 7, 143
+# msg : 81
+
+# find n = 143 with primes
+Primes = File.read("primes.txt").split(",")
+
+print "Modbase target: "
+target = gets.chomp.to_i
+
+def bruteforce(target)
+	Primes.each do |p|
+		second = Primes.dup
+		second.delete p
+		second.each do |p2|
+			prod = p.to_i * p2.to_i
+			if prod == target then
+				return p, p2
+			end
+		end
+	end
+end
+
+p1, p2 = bruteforce(target)
+puts "Found primes:"
+puts p1, p2

ma5/rsa/rsa.rb

@@ -0,0 +1,50 @@
+module RSA
+	def self.mod_inv(a, m)
+		(1..m).each{|x| break x if (a*x % m == 1)}
+	end
+
+	class Key
+		def initialize(p1, p2)
+			@p1 = p1
+			@p2 = p2
+			@n = p1 * p2
+			@phi = (p1-1)*(p2-1)
+
+			(2...@phi).each do |e|
+				if( e.gcd(@phi) == 1 ) then
+					@e = e
+					break
+				end
+			end
+
+			@d = RSA.mod_inv(@e, @phi)
+		end
+
+		def pubkey
+			return @e, @phi
+		end
+
+		def privkey
+			return @d, @phi
+		end
+	end
+
+	def self.encrypt(text, key)
+		n, mod = key.pubkey
+		p [n, mod]
+		text_enc = ""
+		text.split("").each_with_index do |c, i|
+			charint = c.ord ** n
+			p charint
+			charint %= mod
+			p charint
+			puts "enc #{c.ord} -> #{charint}"
+			text_enc += charint.chr
+		end
+
+		return text_enc
+	end
+
+	def self.decrypt(text)
+	end
+end