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  Re: RSA question as well, following B. Schneier book example         


Author:
Date: Dec 28, 2006 23:31

Mike Amling a écrit :
>> They do not have the same lenght. Is this normal?
>
> Yes, this is normal. The ciphertexts should all be in the range
> 0..3336, and they are. No one ever claimed they'd have the same number
> of decimal digits as each other or as their plaintexts, when you omit
> leading zeros.
>
>
> --Mike Amling

Thank you all for your answers.

Carlos Moreno was right, it was 17, not 7, my mistake.

Regarding the lenght of cyphered message blocs, i cannot just put them
together and send them, as the receiver Alice will not be able the know
which size is each bloc.

If i understand you, i have to fill with leading zero's ? in this case,
is this last column ok?
Show full article (1.21Kb)
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  Re: RSA question as well, following B. Schneier book example         


Author: Carlos Moreno
Date: Dec 28, 2006 21:13

M Jason Hinek wrote:
> Something else that you should be aware of is that if you choose your
> primes first, you might not be able to use any public exponent that you
> wish. The public exponent e must be relatively prime to both p-1 and q-1.
> In the example you used, a public exponent e=7

He likely meant 17, and not 7.

What you mention is precisely the reason (one of the two reasons) why
typical public exponents considered "valid" are 3, 17, and 65537 ---
they're all prime numbers that only have two ones in their binary
representations; prime numbers guarantees that they are relatively
prime to whatever else; and luckily, these are all of the form
2^n + 1, meaning that the exponentiation (square-and-multiply or
its cousins) is efficient (comparatively to some other arbitrary
exponents).

Carlos
--
3 Comments
  Re: Enigma machine strenght using a computer         


Author: Jean-François Michaud
Date: Dec 28, 2006 14:00

David Eather wrote:
> Jean-François Michaud wrote:
>> Hello,
>>
>> I was wondering what kind of encryption strenght we were looking at for
>> an enigma machine with say 512 rotors, each rotor having 256 (0 to 255)
>> states to rotate into.
>>
>> I know it depends on how the rotors move but what bounds are we looking
>> at? At least what and at most what?
>>
>> The machine taking any character in extended ASCII (between 0 and 255)
>> and stays within 0 and 255.
>>
>> Regards
>> Jean-Francois Michaud
>>
>
> Give up any idea of reviving a rotor machine for a serious purpose.
> ...
Show full article (1.75Kb)
1 Comment
  OT:Peter Gutmann - Nice Article!         


Author: Timoleon
Date: Dec 28, 2006 06:17

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http://www.linuxtoday.com/it_management/2006122800935SCMS

Makes me want to blow Windows Vista Ultimate off my laptop and go back
to XP...Linux...95...OS/2...3.1 --- no, wait --- MS-DOS 3.2!

It sounds like what is coming is a terminal/fatal illness, that
absolutely nothing will cure :-(

Tim
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1 Comment