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# frozen_string_literal: true
module Zip
module TraditionalEncryption # :nodoc:
def initialize(password)
@password = password
reset_keys!
end
def header_bytesize
12
end
def gp_flags
0x0001 | 0x0008
end
protected
def reset_keys!
@key0 = 0x12345678
@key1 = 0x23456789
@key2 = 0x34567890
@password.each_byte do |byte|
update_keys(byte.chr)
end
end
def update_keys(num)
@key0 = ~Zlib.crc32(num, ~@key0)
@key1 = (((@key1 + (@key0 & 0xff)) * 134_775_813) + 1) & 0xffffffff
@key2 = ~Zlib.crc32((@key1 >> 24).chr, ~@key2)
end
def decrypt_byte
temp = (@key2 & 0xffff) | 2
((temp * (temp ^ 1)) >> 8) & 0xff
end
end
class TraditionalEncrypter < Encrypter # :nodoc:
include TraditionalEncryption
def header(mtime)
[].tap do |header|
(header_bytesize - 2).times do
header << Random.rand(0..255)
end
header << (mtime.to_binary_dos_time & 0xff)
header << (mtime.to_binary_dos_time >> 8)
end.map { |x| encode x }.pack('C*')
end
def encrypt(data)
data.unpack('C*').map { |x| encode x }.pack('C*')
end
def data_descriptor(crc32, compressed_size, uncompressed_size)
[0x08074b50, crc32, compressed_size, uncompressed_size].pack('VVVV')
end
def reset!
reset_keys!
end
private
def encode(num)
t = decrypt_byte
update_keys(num.chr)
t ^ num
end
end
class TraditionalDecrypter < Decrypter # :nodoc:
include TraditionalEncryption
def decrypt(data)
data.unpack('C*').map { |x| decode x }.pack('C*')
end
def reset!(header)
reset_keys!
header.each_byte do |x|
decode x
end
end
def check_integrity!(_io); end
private
def decode(num)
num ^= decrypt_byte
update_keys(num.chr)
num
end
end
end
# Copyright (C) 2002, 2003 Thomas Sondergaard
# rubyzip is free software; you can redistribute it and/or
# modify it under the terms of the ruby license.
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