Class: Archive::Zip::Codec::TraditionalEncryption::Writer

Inherits:
Base
  • Object
show all
Defined in:
lib/archive/zip/codec/traditional_encryption/writer.rb

Overview

Archive::Zip::Codec::TraditionalEncryption#compressor method.

Instance Method Summary collapse

Methods inherited from Base

#seek

Constructor Details

#initialize(delegate, password, mtime, autoclose: true) ⇒ Writer

Returns a new instance of Writer.



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# File 'lib/archive/zip/codec/traditional_encryption/writer.rb', line 16

def initialize(delegate, password, mtime, autoclose: true)
  super

  # A 12 byte header to protect the encrypted file data from attack.  The
  # first 10 bytes are random, and the last 2 bytes are the low order word
  # in little endian byte order of the last modified time of the entry in
  # DOS format.
  @header =
    (10.times.map { |_| rand(256) } + [DOSTime.new(@mtime).to_i].pack('V')[0, 2].bytes)
    .map do |byte|
      crypt_char = (byte ^ decrypt_byte).chr
      update_keys(byte.chr)
      crypt_char
    end
    .join
end

Instance Method Details

#write(buffer, length: buffer.bytesize) ⇒ Object

Encrypts and writes string to the delegate IO object. Returns the number of bytes of string written.



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# File 'lib/archive/zip/codec/traditional_encryption/writer.rb', line 35

def write(buffer, length: buffer.bytesize)
  result = write_header
  return result if Symbol === result

  buffer = buffer[0, length] if length < buffer.bytesize
  buffer.to_enum(:each_byte).each_with_index do |byte, idx|
    result = super((byte ^ decrypt_byte).chr)
    if Symbol === result
      return idx if idx > 0
      return result
    end
    update_keys(byte.chr)
    @bytes_processed += 1
  end

  buffer.bytesize
end