From: "David D." <lists@...>
Date: 2013-05-24T07:43:10+09:00
Subject: Re: why first 16 bytes are wrong with ruby openssl aes 128 cbc ?

I'm sorry for my late. Thank Ryan.

I'm sorry but auth_tag doesn't exist for ruby 1.8.7. For be clear a
exemple this : http://pastebin.com/nFgfyXem who is an encrypted file
encode to base64.
didier@laptop-E520:/tmp$ pbget "http://pastebin.com/p08QTXru" | base64
-d > file_enc
didier@laptop-E520:/tmp$ md5sum file_enc
30b8f5e7d700c108cd9815c00ca1de2d  file_enc

pbget is this http://pastebin.com/fXsuA9bn a bash program for pastebin.

decrypte the file :

didier@laptop-E520:/tmp/ruby_forum$ openssl aes-128-cbc -d -in file_enc
-out pic_bash.jpg -nosalt -iv 00000000000000000000000000000001 -K
7ffb8032dff33aef9aa92e9ac96239d3

ruby code :

require 'openssl'

c = OpenSSL::Cipher::Cipher.new("aes-128-cbc")
c.decrypt
c.key = "\177\373\2002\337\363:\357\232\251.\232\311b9\323"
c.iv = "00000000000000000000000000000001"
data = File.read("/tmp/file_enc")
d = c.update(data)
d << c.final
file = File.open("/tmp/file_decrypt_ruby", "w")
file.write(d)
file.close

didier@laptop-E520:/tmp/ruby_forum$ hd pic_bash.jpg | head
00000000  ff d8 ff e1 22 d2 45 78  69 66 00 00 4d 4d 00 2a
|....".Exif..MM.*|
00000010  00 00 00 08 00 0c 01 1a  00 05 00 00 00 01 00 00
|................|
00000020  01 46 01 1b 00 05 00 00  00 01 00 00 01 4e 01 28
|.F...........N.(|
00000030  00 03 00 00 00 01 00 02  00 00 02 13 00 03 00 00
|................|
00000040  00 01 00 01 00 00 87 69  00 04 00 00 00 01 00 00
|.......i........|
00000050  00 9e 01 3b 00 02 00 00  00 0d 00 00 01 56 01 0e
|...;.........V..|
00000060  00 02 00 00 00 13 00 00  01 64 01 32 00 02 00 00
|.........d.2....|
00000070  00 14 00 00 01 78 01 0f  00 02 00 00 00 06 00 00
|.....x..........|
00000080  01 8c 01 10 00 02 00 00  00 08 00 00 01 92 01 31
|...............1|
00000090  00 02 00 00 00 08 00 00  01 9a 01 12 00 03 00 00
|................|

didier@laptop-E520:/tmp/ruby_forum$ hd file_decrypt_ruby | head
00000000  cf e8 cf d1 12 e2 75 48  59 56 30 30 7d 7d 30 1b
|......uHYV00}}0.|
00000010  00 00 00 08 00 0c 01 1a  00 05 00 00 00 01 00 00
|................|
00000020  01 46 01 1b 00 05 00 00  00 01 00 00 01 4e 01 28
|.F...........N.(|
00000030  00 03 00 00 00 01 00 02  00 00 02 13 00 03 00 00
|................|
00000040  00 01 00 01 00 00 87 69  00 04 00 00 00 01 00 00
|.......i........|
00000050  00 9e 01 3b 00 02 00 00  00 0d 00 00 01 56 01 0e
|...;.........V..|
00000060  00 02 00 00 00 13 00 00  01 64 01 32 00 02 00 00
|.........d.2....|
00000070  00 14 00 00 01 78 01 0f  00 02 00 00 00 06 00 00
|.....x..........|
00000080  01 8c 01 10 00 02 00 00  00 08 00 00 01 92 01 31
|...............1|
00000090  00 02 00 00 00 08 00 00  01 9a 01 12 00 03 00 00
|................|

This is independent of key. Thank you.

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