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Contents
# -*- coding: binary -*-
##
#
# RFB protocol support
#
# by Joshua J. Drake <jduck>
#
# Based on:
# vnc_auth_none contributed by Matteo Cantoni <goony[at]nothink.org>
# vnc_auth_login contributed by carstein <carstein.sec[at]gmail.com>
#
##
# Required for VNC authentication
require 'openssl'
module Rex
module Proto
module RFB
##
# A bit of information about the DES algorithm was found here:
# http://www.vidarholen.net/contents/junk/vnc.html
#
# In addition, VNC uses two individual 8 byte block encryptions rather than
# using any block mode (like cbc, ecb, etc).
##
class Cipher
def self.mangle_password(password)
key = ''
key = password.dup if password
key.slice!(8,key.length) if key.length > 8
key << "\x00" * (8 - key.length) if key.length < 8
# We have to mangle the key so the LSB are kept vs the MSB
[key.unpack('B*').first.scan(/.{8}/).map! { |e| e.reverse }.join].pack('B*')
end
def self.encrypt(plain, password)
key = self.mangle_password(password)
# pad the plain to 16 chars
plain << ("\x00" * (16 - plain.length)) if plain.length < 16
# VNC auth does two 8-byte blocks individually instead supporting some block mode
cipher = ''
2.times { |x|
c = OpenSSL::Cipher::Cipher.new('des')
c.encrypt
c.key = key
cipher << c.update(plain[x*8, 8])
}
cipher
end
#
# NOTE: The default password is that of winvnc/etc which is used for
# encrypting the password(s) on disk/in registry.
#
def self.decrypt(cipher, password = "\x17\x52\x6b\x06\x23\x4e\x58\x07")
key = self.mangle_password(password)
# pad the cipher text to 9 bytes
cipher << ("\x00" * (9 - cipher.length)) if cipher.length < 9
# NOTE: This only does one 8 byte block
plain = ''
c = OpenSSL::Cipher::Cipher.new('des')
c.decrypt
c.key = key
c.update(cipher)
end
end
end
end
end
Version data entries
15 entries across 15 versions & 3 rubygems