Ruby implementation of Redline99's "X" value decryption code (Xbox 360)

xval.rb

# xval.rb  - Ruby implementation of Redline99's "X" value decryption code for the Xbox 360 by CLK
# See https://gist.github.com/2669789 for Python code
require 'optparse'
require 'openssl'

# Define our constants
FLAG_SSB_NONE                           = 0x0000
FLAG_SSB_AUTH_EX_FAILURE                = 0x0001
FLAG_SSB_AUTH_EX_NO_TABLE               = 0x0002
FLAG_SSB_AUTH_EX_RESERVED               = 0x0004
FLAG_SSB_INVALID_DVD_GEOMETRY           = 0x0008
FLAG_SSB_INVALID_DVD_DMI                = 0x0010
FLAG_SSB_DVD_KEYVAULT_PAIR_MISMATCH     = 0x0020
FLAG_SSB_CRL_DATA_INVALID               = 0x0040
FLAG_SSB_CRL_CERTIFICATE_REVOKED        = 0x0080
FLAG_SSB_UNAUTHORIZED_INSTALL           = 0x0100
FLAG_SSB_KEYVAULT_POLICY_VIOLATION      = 0x0200
FLAG_SSB_CONSOLE_BANNED                 = 0x0400
FLAG_SSB_ODD_VIOLATION                  = 0x0800

def DecryptXval(serial, xval)
  # Remove dashes from the xval
  xval = xval.delete('-') 
  # Convert the xval to a byte array
  xval = xval.scan(/../).map(&:hex)
  # Conver that back into a string
  xval = xval.pack('c*')
  # Make sure that the serial/xval lengths are good
  fail if serial.length != 0xC
  fail if xval.length != 0x8
  # Get the DES key (bytes 0-8 of the hash)
  serial.encode!("ascii")
  deskey = OpenSSL::HMAC.digest("sha1", serial + "\0", "XBOX360SSB")[0, 8]
  fail if deskey.length != 0x8
  
  # Decrypt the X value
  cipher = OpenSSL::Cipher::Cipher.new("des-ecb")
  cipher.decrypt
  cipher.key = deskey
  # Must set the padding to 0
  cipher.padding = 0
  ciphertext = cipher.update(xval) + cipher.final
  return ciphertext
end

def GetResults(result)
  xval = result.unpack('LL*')
  xval_h = xval[0]
  xval_l = xval[1]
  if(xval_h == 0 && xval_l == 0)                              # nothing is flagged in secdata.bin, all is good from this standpoint        
    return "Secdata is Clean"
  elsif(xval_h == 0xFFFFFFFF && xval_l == 0xFFFFFFFF)         # secdata was prob tampered with
    return "Secdata is invalid"
  elsif (xval_h != 0 && xval_l != 0)                          # most likely the serial or xval is incorrect
    return "Secdata decryption error.  Check your serial number and X value to ensure they are correct"
  else                                                        # the high dword = 0 and low dword not 0
                                                              # afaik best check. have to look at disassembly more
    if(xval_l & FLAG_SSB_AUTH_EX_FAILURE)
      return "AuthEx Challenge Failure"                       # AP25 related
    end
    if(xval_l & FLAG_SSB_AUTH_EX_NO_TABLE)
      return "AuthEx Table missing"                           # AP25 related
    end
    if(xval_l & FLAG_SSB_AUTH_EX_RESERVED)
      return "AuthEx Reserved Flag"                           # AP25 related
    end
    if(xval_l & FLAG_SSB_INVALID_DVD_GEOMETRY)
      return "Invalid DVD Geometry"
    end
    if(xval_l & FLAG_SSB_INVALID_DVD_DMI)
      return "Invalid DVD DMI"
    end
    if(xval_l & FLAG_SSB_DVD_KEYVAULT_PAIR_MISMATCH)
      return "DVD Keyvault Pair Mismatch"
    end
    if(xval_l & FLAG_SSB_CRL_DATA_INVALID)
      return "Invalid CRL Data"
    end
    if(xval_l & FLAG_SSB_CRL_CERTIFICATE_REVOKED)
      return "CRL Certificate Revoked"
    end
    if(xval_l & FLAG_SSB_UNAUTHORIZED_INSTALL)
      return "Unauthorized Install"
    end
    if(xval_l & FLAG_SSB_KEYVAULT_POLICY_VIOLATION)
      return "Keyvault Policy Violation"
    end
    if(xval_l & FLAG_SSB_CONSOLE_BANNED)
      return "Console Banned"
    end
    if(xval_l & FLAG_SSB_ODD_VIOLATION)
      return "ODD Violation"
    end
    if(xval_l & 0xFFFFF000)                                   # mask for bits we dont have a description for,
                                                              # note: we are not looking at the hi dword yet
      return "Unknown Violation(s)"
    end
  end 
end

# Parse the input arguments
options = {}
optparser = OptionParser.new do |opts|
  opts.banner = "Usage: xval.rb [options]"
  # Serial switch
  opts.on('-s', '--serial SERIAL', 'Console serial number') do |v|
    options[:serial] = v
  end
  # X value switch
  opts.on('-x', '--xval XVAL', '"X:" Value shown on the dashboard') do |v|
    options[:xval] = v
  end
  # Help switch
  opts.on( '-h', '--help', 'Display this screen' ) do
    puts opts
    exit
  end
end

# Parse the args and clear ARGV
optparser.parse!

# Make sure that we were given some args
if (options.length == 0)
  puts optparser
  return
elsif (options[:serial] == nil)
  puts "No serial number passed"
  puts optparser
  return
elsif (options[:xval] == nil)
  puts "No X value passed"
  puts optparser
  return
end

# Get some results
puts GetResults(DecryptXval(options[:serial], options[:xval]))