WiP: RSA Challenge - work in progress...

Gemfile

@@ -35,6 +35,8 @@ gem 'smbhash'
 gem 'digest-sha3'
 gem 'digest-whirlpool'
 gem 'digest-siphash'
+gem 'scrypt'
+gem 'rsa'
 
 #development only gems go here
 group :test, :development do

Gemfile.lock

@@ -107,6 +107,7 @@ GEM
     rmagick (2.16.0)
     rqrcode (0.10.1)
       chunky_png (~> 1.0)
+    rsa (0.1.4)
     rsync (1.0.9)
     ruby-graphviz (1.2.3)
     rubyzip (1.2.2)
@@ -160,6 +161,7 @@ DEPENDENCIES
   redcarpet
   rmagick
   rqrcode
+  rsa
   ruby-graphviz
   scrypt
   smbhash

modules/generators/challenges/crypto/rsa_challenge/secgen_local/local.rb

@@ -0,0 +1,77 @@
+#!/usr/bin/ruby
+require_relative '../../../../../../lib/objects/local_string_encoder.rb'
+require 'rsa'
+
+class RSAChallenge < StringEncoder
+
+  def initialize
+    super
+    self.module_name = 'RSA Challenge Generator'
+    self.strings_to_encode = ['flag']
+  end
+
+  def encode(str)
+
+    # 1. Choose two distinct prime numbers p and q.
+
+    # For security purposes, the integers p and q should be chosen at random, and should be of similar bit-length.
+    # Prime integers can be efficiently found using a primality test.
+
+    # 2. Compute n = pq.
+
+
+    # RSA Challenge Generator style:
+    # RSA Encryption parameters. Public key: [e,N].
+    # e:	65537
+    # N:	793317875048486727769682005180064761
+    # Cipher:	378078478708458631194952101156921202
+
+    # PicoCTF style:
+    #
+    # p =  9648423029010515676590551740010426534945737639235739800643989352039852507298491399561035009163427050370107570733633350911691280297777160200625281665378483
+    # q =  11874843837980297032092405848653656852760910154543380907650040190704283358909208578251063047732443992230647903887510065547947313543299303261986053486569407
+    # e =  65537
+    # c =  83208298995174604174773590298203639360540024871256126892889661345742403314929861939100492666605647316646576486526217457006376842280869728581726746401583705899941768214138742259689334840735633553053887641847651173776251820293087212885670180367406807406765923638973161375817392737747832762751690104423869019034
+    #
+    # Use RSA to find the secret message
+    #
+
+    output_data = "Solve the challenge using RSA!\n"
+
+    key_pair = RSA::KeyPair.generate(60)
+
+    e = key_pair.public_key.exponent
+    n = key_pair.public_key.modulus
+    ciphertext = key_pair.encrypt(str)
+    c = Integer("0x#{ciphertext.unpack("H*")[0].upcase}")
+
+    output_data += "e: #{e}\n"
+    output_data += "n: #{n}\n"
+    output_data += "ciphertext: #{c}\n"
+
+    self.outputs << output_data
+  end
+
+
+  # def get_options_array
+  #   super + [['--base64_image', GetoptLong::REQUIRED_ARGUMENT],
+  #           ['--strings_to_leak', GetoptLong::REQUIRED_ARGUMENT]]
+  # end
+
+  # def process_options(opt, arg)
+  #   super
+  #   case opt
+  #     when '--base64_image'
+  #       self.base64_image << arg;
+  #     when '--strings_to_leak'
+  #       self.strings_to_leak << arg;
+  #   end
+  # end
+
+  # def encoding_print_string
+  #   'base64_image: <selected_image>' + print_string_padding +
+  #   'strings_to_leak: ' + self.strings_to_leak.to_s
+  # end
+end
+
+RSAChallenge.new.run

modules/generators/challenges/crypto/rsa_challenge/secgen_metadata.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0"?>
+
+<generator xmlns="http://www.github/cliffe/SecGen/generator"
+           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+           xsi:schemaLocation="http://www.github/cliffe/SecGen/generator">
+  <name>RSA Challenge Generator</name>
+  <author>Thomas Shaw</author>
+  <module_license>MIT</module_license>
+  <description>RSA Generator.</description>
+
+  <type>rsa</type>
+  <type>challenge_generator</type>
+  <type>crypto_challenge_generator</type>
+  <type>local_calculation</type>
+  <platform>linux</platform>
+  <platform>windows</platform>
+
+  <!--<read_fact>base64_image</read_fact>-->
+
+  <!--<default_input into="base64_image">-->
+    <!--<generator type="random_image"/>-->
+  <!--</default_input>-->
+
+  <output_type>string_challenge</output_type>
+</generator>