Re: Double Encryption Illegal?
From: Paul Schlyter <pausch_at_saafNOSPAM.se>
Date: 17 Sep 2000 15:25:39 +0200
Message-ID: <8q2goj$er0$1_at_merope.saaf.se>
>> In article <8pvnav$gdt$1_at_nnrp1.deja.com>,
>> Tom St Denis <stdenis_at_compmore.net> wrote:
>>
>>> In article <39C350A8.7F8DD52F_at_t-online.de>,
>>> Mok-Kong Shen <mok-kong.shen_at_t-online.de> wrote:
>>>>
>>>>
>>>> PRdO wrote:
>>>>>
>>>>> IMHO double encryption *does not* add security, i.e., double
>>>>> encryption in 128-bit doesn't equal better encryption.
>>>>> (since encryption uses random keys, "randoming" again the data
>>>>> would not lead to more secure data).
>>>>
>>>> If you have an algorithm that does a perfect job (do
>>>> you happen to have one?), then there is by definition
>>>> nothing to improve. Otherwise, multiple encryption may
>>>> help, if done properly.
>>>
>>> Ah but double encryption is not the way to go about it.
>>
>> So you're claiming that triple-DES is no more secure than single-
>> DES ???
Date: 17 Sep 2000 15:25:39 +0200
Message-ID: <8q2goj$er0$1_at_merope.saaf.se>
In article <8q273q$5aj$1_at_nnrp1.deja.com>, Tom St Denis <stdenis_at_compmore.net> wrote:
> In article <8q1tea$bhp$1_at_merope.saaf.se>, > pausch_at_saafNOSPAM.se (Paul Schlyter) wrote:
>> In article <8pvnav$gdt$1_at_nnrp1.deja.com>,
>> Tom St Denis <stdenis_at_compmore.net> wrote:
>>
>>> In article <39C350A8.7F8DD52F_at_t-online.de>,
>>> Mok-Kong Shen <mok-kong.shen_at_t-online.de> wrote:
>>>>
>>>>
>>>> PRdO wrote:
>>>>>
>>>>> IMHO double encryption *does not* add security, i.e., double
>>>>> encryption in 128-bit doesn't equal better encryption.
>>>>> (since encryption uses random keys, "randoming" again the data
>>>>> would not lead to more secure data).
>>>>
>>>> If you have an algorithm that does a perfect job (do
>>>> you happen to have one?), then there is by definition
>>>> nothing to improve. Otherwise, multiple encryption may
>>>> help, if done properly.
>>>
>>> Ah but double encryption is not the way to go about it.
>>
>> So you're claiming that triple-DES is no more secure than single-
>> DES ???
> > Read my message. Geez. I said "double" encryption is not the way to > go about added security.
But you believe "triple" encryption is, since you don't think your statement applied to triple-DES?
One cannot generally state that multiple encryption enhances, or does not enhance, security -- it depends a lot on the encryption used.
Consider for instance the good ol' Caesar cipher: applying it multiple times with different "keys" makes the final encryption no safer than if it was applied only once with one single "key".
Now, instead consider DES, where applying it three times does indeed make tne encryption safer than if applied only once -- that's why 3DES is so popular.
-- ---------------------------------------------------------------- Paul Schlyter, Swedish Amateur Astronomer's Society (SAAF) Grev Turegatan 40, S-114 38 Stockholm, SWEDEN e-mail: pausch at saaf dot se or paul.schlyter at ausys dot se WWW: http://hotel04.ausys.se/pausch http://welcome.to/pauschReceived on Sun Sep 17 2000 - 15:25:39 CEST