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# Some very simple 'encryption' operations.
# Just for some dumb obsfucation.
class Cipher
def initialize(shuffled)
normal = ('a'..'z').to_a + ('A'..'Z').to_a + ('0'..'9').to_a + [' ']
@map = normal.zip(shuffled).inject(:encrypt => {} , :decrypt => {}) do |hash,(a,b)|
hash[:encrypt][a] = b
hash[:decrypt][b] = a
hash
end
end
def encrypt(str)
str.split(//).map { |char| @map[:encrypt][char] }.join
end
def decrypt(str)
str.split(//).map { |char| @map[:decrypt][char] }.join
end
end
require_relative './trie'
require_relative './cipher'
t = Trie.new
t.push("rbc4pr050n1y", "this isnt the flag")
t.push("m4tz i5 my h3r0", "neither is this")
t.push("d1dy0u r4d4r3 y0ur ruby?", "nope lots of fake flags")
t.push("b3c4u5e 17 uses llvm th15 me4nz sp33d", "wow not this either")
t.push("d1d y0u tr13 be1ng m04r 2337?", "good boy this is the flag")
t.push("d1d y0u kn0w tr13d n07 b31n6 a n00b?", "lole n1c3 try")
t.push("rbx 1z e4zy 2 r34d", "1 c4n r34d th15 ju57 l1k3 x86 0r 3n6L15h!")
t.push("d1d y0u h4xd 17 y3t", "stop being such a n00b and get the flag")
t.push("python is for noobs", "not the flag but a true statement ;)")
m = Marshal.dump(t)
File.open('trie.dump', 'w') {|f| f.write(m) }
# a simple prefix tree data structure
require './cipher'
class Trie
def push_recursive(node, string, index, value)
char = string[index]
node = Node.new(char, value) if node.nil?
if (char < node.char)
node.left = push_recursive(node.left, string, index, value)
elsif (char > node.char)
node.right = push_recursive(node.right, string, index, value)
elsif (index < string.length - 1)
node.mid = push_recursive(node.mid, string, index + 1, value)
else
node.end = true
node.value = value
end
return node
end
def get_recursive(node, string, index)
return nil if node.nil?
char = string[index]
if (char < node.char)
return get_recursive(node.left, string, index)
elsif (char > node.char)
return get_recursive(node.right, string, index)
elsif (index < string.length - 1)
return get_recursive(node.mid, string, index + 1)
else
if node.last?
return [node.char, node.value]
else
return nil
end
end
end
def initialize
@root = nil
end
def push(key, value)
cipher = Cipher.new ["K", "D", "w", "X", "H", "3", "e", "1", "S", "B", "g", "a", "y", "v", "I", "6", "u", "W", "C", "0", "9", "b", "z", "T", "A", "q", "U", "4", "O", "o", "E", "N", "r", "n", "m", "d", "k", "x", "P", "t", "R", "s", "J", "L", "f", "h", "Z", "j", "Y", "5", "7", "l", "p", "c", "2", "8", "M", "V", "G", "i", " ", "Q", "F"]
key = cipher.encrypt key.to_s
return nil if key.empty?
@root = push_recursive(@root, key, 0, value)
return value
end
alias_method :[]=, :push
def has_key?(key)
key = key.to_s
return false if key.empty?
nope = get_recursive(@root, key, 0).nil?
return !nope
end
def get(key)
cipher = Cipher.new ["K", "D", "w", "X", "H", "3", "e", "1", "S", "B", "g", "a", "y", "v", "I", "6", "u", "W", "C", "0", "9", "b", "z", "T", "A", "q", "U", "4", "O", "o", "E", "N", "r", "n", "m", "d", "k", "x", "P", "t", "R", "s", "J", "L", "f", "h", "Z", "j", "Y", "5", "7", "l", "p", "c", "2", "8", "M", "V", "G", "i", " ", "Q", "F"]
key = cipher.encrypt key.to_s
return nil if key.empty?
node = get_recursive(@root, key, 0)
if node != nil
return node.last
else
return nil
end
alias_method :[],:get
end
class Node
attr_accessor :left, :mid, :right, :char, :value, :end
def initialize(char, value)
@char = char
@value = value
@left = @mid = @right = nil
@end = false
end
def last?
return @end == true
end
end
end
require_relative './trie'
require_relative './cipher'
puts " [*] Greetings to all of the eiltes here [*]"
puts "--- I heard you guys all hate ruby, so I have decided to be nice---"
puts " --- enjoy this great bytecode instead! ---"
puts ""
puts ""
print "So, you can tell me now... what's the flag? "
flag = gets.chomp
dumped = File.read('trie.dump')
t = Marshal.load dumped
res = t.get(flag)
if not res.nil?
puts res
else
puts "nop"
end
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