# coding: ASCII-8BIT
require 'ctf'

S = [ 0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76, 0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0, 0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15, 0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75, 0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84, 0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF, 0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8, 0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2, 0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73, 0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB, 0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79, 0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08, 0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A, 0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E, 0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF, 0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16]
INVS = [ 0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB, 0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB, 0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E, 0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25, 0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92, 0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84, 0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06, 0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B, 0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73, 0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E, 0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B, 0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4, 0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F, 0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF, 0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61, 0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D ]

Lper,Luper=[51, 43, 42, 47, 19, 49, 10, 23, 18, 11, 1, 60, 24, 31, 40, 54, 12, 56, 38, 59, 52, 6, 50, 13, 53, 34, 27, 17, 2, 3, 29, 26, 21, 30, 62, 20, 45, 16, 39, 28, 48, 35, 15, 22, 63, 58, 32, 57, 25, 33, 14, 36, 44, 37, 0, 8, 41, 5, 7, 9, 55, 46, 4, 61], [54, 10, 28, 29, 62, 57, 21, 58, 55, 59, 6, 9, 16, 23, 50, 42, 37, 27, 8, 4, 35, 32, 43, 7, 12, 48, 31, 26, 39, 30, 33, 13, 46, 49, 25, 41, 51, 53, 18, 38, 14, 56, 2, 1, 52, 36, 61, 3, 40, 5, 22, 0, 20, 24, 15, 60, 17, 47, 45, 19, 11, 63, 34, 44]

def subStr(toSub)
  toSub.unpack("C*").map{|a|S[a].chr}.join
end

def unSubStr(toSub)
  toSub.unpack("C*").map{|a|INVS[a].chr}.join
end

def permute(str)
  p1 = str.unpack("Q")[0]
  [64.times.inject(0){ |o, i| o |= ((p1 & (1 << i)) >> i) << Lper[i]}].pack('Q')
end

def unpermute(str)
  p1 = str.unpack("Q")[0]
  [64.times.inject(0){ |o, i| o |= ((p1 & (1 << i)) >> i) << Luper[i]}].pack('Q')
end

def encrypt(str, key)
  k1, k2, k3 = key.chars.each_slice(8).map{|a|a.join}
  k3.reverse!
  str.chars.each_slice(8).map{|a|a.join}.map do |str|
    # stage1
    str = permute(subStr(str ^ k1))
    # stage2
    str = permute(subStr(str ^ k2))
    # stage3
    str.reverse!
    [(str.unpack("Q")[0] + k3.unpack("Q")[0]) % (2**64-1)].pack("Q")
  end.inject(:+)
end

def inv_stage1(str, key)
  unSubStr(unpermute(str)) ^ key[0, 8]
end

def solve2(x, y, z, eql_mode)
  # (x - k) ^ (y - k) & z == (x - k) ^ (y - k)になるkが存在するかどうか。eql_modeがtrueの時は(x-k)^(y-k) = zになるkが存在するかどうか
  state = [true, false, false, false]
  65.times do |i|
    nstate = [false, false, false, false]
    xbit = x >> i & 1
    ybit = y >> i & 1
    state.each.with_index.select{|a,_|a}.each do |_,j|
      kx = (j >> 0 & 1)
      ky = (j >> 1 & 1)
      next if kx ^ ky ^ xbit ^ ybit != 0 && z >> i & 1 == 0
      next if kx ^ ky ^ xbit ^ ybit != 1 && z >> i & 1 == 1 && eql_mode
      nkx = (xbit == 0 && kx == 1) ? 1 : 0
      nky = (ybit == 0 && ky == 1) ? 1 : 0
      nstate[(nkx << 0) | (nky << 1)] = true
      nkx = (xbit == 1 && kx == 0) ? 0 : 1
      nky = (ybit == 1 && ky == 0) ? 0 : 1
      nstate[(nkx << 0) | (nky << 1)] = true
    end
    return false if nstate.none? # もう駄目
    state = nstate
  end
  return true
end

def solve(x, y, z, eql = false, m = 2 ** 64 - 1)
  solve2(x, y, z, eql) || solve2(x + m, y, z, eql) || solve2(x, y + m, z, eql) || solve2(x + m, y + m, z, eql)
end

if ARGV.size >= 2 # 引数があるなら通信してKeyを得る
  require 'digest/sha1'
  def encrypt(str, key)
    begin
      s = TCPSocket.open(ARGV[0], ARGV[1])
      start = s.expect(/with ([A-Za-z0-9\/+=]{16})/)[1]
      puts 'Encrypting length: %d ' % str.size
      while true
        rand = Array.new(5){[*'a'..'z'].sample}.join
        if Digest::SHA1.hexdigest(start + rand).end_with?('ffff')
          s.print start + rand
          s.flush
          break
        end
      end
      s.print [str.size].pack("s")
      s.print str
      s.expect("'")
      ret = s.expect(/[^\\]'/)[0][0..-2]
      ret = ret.gsub(/\\(x[0-9a-f]{2}|[a-w'\\])/) do |c|
        eval "\"#{c}\""
      end
      fail unless ret.size == str.size
      return ret
    rescue => e
      sleep 12
      retry
    end
  end
end
KEY = 'The fifty secret letters' # ローカルテスト用のkey
key = ''
# 最初の8文字を特定する。一回目のsubStr後に1bitの差が出た時に、どこが変化しうるか(bit1, bit2)を求め、それと合致しているようなjを求める。
8.times do |i|
  bit1 = bit2 = 0
  256.times do |s|
    str3 = (str2 = (str1 = "X" * 8).dup).dup
    str1[i] = s.chr
    str2[i] = (s^1).chr
    str3[i] = (s^2).chr
    b1 = permute(str1) ^ permute(str2)
    b2 = permute(str1) ^ permute(str3)
    idx1 = /[\x01-\xff]/ =~ b1
    idx2 = /[\x01-\xff]/ =~ b2
    str1[idx1] = s.chr
    str2[idx2] = s.chr
    bit1 |= (permute(subStr(str1)) ^ permute(subStr(str1 ^ b1))).reverse.unpack("Q*")[0]
    bit2 |= (permute(subStr(str2)) ^ permute(subStr(str2 ^ b2))).reverse.unpack("Q*")[0]
  end
  e_all = ''
  256.times do |j|
    4.times do
      s3 = (s2 = (s1 = Array.new(8){rand(256).chr}.join).dup).dup
      s1[i] = j.chr ^ INVS[0]
      s2[i] = j.chr ^ INVS[1]
      s3[i] = j.chr ^ INVS[2]
      e_all << s1 << s2 << s3
    end
  end
  e_all = encrypt(e_all, KEY)
  256.times do |j|
    ok = true
    4.times do
      d1 = e_all[0,8].unpack("Q*")[0]
      d2 = e_all[8,8].unpack("Q*")[0]
      d3 = e_all[16,8].unpack("Q*")[0]
      e_all = e_all[24..-1]
      ok = false unless solve(d1, d2, bit1) && solve(d1, d3, bit2)
    end
    key << j.chr if ok
  end
end
print "Stage1: "
p key

8.times do |i|
  str3 = (str2 = (str1 = "\0" * 8).dup).dup
  str1[i] = ?B
  str2[i] = ?C
  str3[i] = ?D
  p1 = permute(subStr(str1)).reverse.unpack('Q')[0]
  p2 = permute(subStr(str2)).reverse.unpack('Q')[0]
  p3 = permute(subStr(str3)).reverse.unpack('Q')[0]
  e_all = ''
  256.times do |j|
    4.times do
      s3 = (s2 = (s1 = ?0 * 8).dup).dup
      s1[i] = j.chr ^ ?B
      s2[i] = j.chr ^ ?C
      s3[i] = j.chr ^ ?D
      e_all << inv_stage1(s1, key) << inv_stage1(s2,key) << inv_stage1(s3, key)
    end
  end
  e_all = encrypt(e_all, KEY)
  256.times do |j|
    ok = true
    4.times do
      d1 = e_all[0, 8].unpack('Q')[0]
      d2 = e_all[8, 8].unpack('Q')[0]
      d3 = e_all[16, 8].unpack('Q')[0]
      e_all = e_all[24..-1]
      ok = false unless solve(d1, d2, p1 ^ p2, true) && solve(d1, d3, p1 ^ p3, true)
    end
    key << j.chr if ok
  end
end
print "Stage2: "
p key

# Stage2までで"\0\0\0\0\0\0\0\0"になるような暗号文を作るとStage3のキーがそのまま(逆順で)出てくる
s = inv_stage1(inv_stage1("\0" * 8, key[8, 8]), key)
key << encrypt(s, KEY).reverse
print "Stage3: "
p key