From: Filip Koczorowski <filip.koczorowski@...>
Date: 2006-09-13T17:42:01+09:00
Subject: Base64.decode different behaviour

I am trying to read a value stored in an encrypted cookie in Ruby. The 
cookie value is 3DES-encrypted and then Base64-encoded.

First, I stored the value of a cookie in a file. And then I managed to 
decode and decrypt it successfully using this code:

	key64 = "3DES-CRYPT-KEY-BASE64-ENCODED-READ-FROM-FILE"
	key = Base64.decode64 key64

	cookie64 = "BASE64-ENCODED-COOKIE-VALUE-READ-FROM-FILE"
	cookie = Base64.decode64 cookie64

	des = OpenSSL::Cipher::DES.new(:EDE3)
	des.decrypt
	des.key = key
	des.iv = key[0..7]

	tmp = des.update(cookie)
	value = tmp
	value << des.final

Unfortunately, after running the above code in a Rails controller I get 
an exception "wrong final block length" thrown from the last line. Could 
anyone tell me, why the code works, but when run in a Rails controller 
it doesn't? The only change in Rails version being:

	cookie64 = cookies['COOKIE-NAME']

Trying to find some clue, I commented out the lsat line and then I got a 
too short output - it's missing some data from the input value (which is 
understandable, because "final" is needed for proper decrypting). For 
example:
input string = "qwerty" -> 3DES (in java) -> Base64 (in java) -> 
de-Base64 (in ruby) -> de-3DES (in ruby) -> "qwer"

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