In article <barmar-3AADD2.23045801032006@comcast.dca.giganews.com>,
Barry Margolin <barmar@alum.mit.edu> wrote:

> In article <k2jNf.82228$sa3.63791@pd7tw1no>,
> roberson@hushmail.com (Walter Roberson) wrote:
>
> > In article <1141197605.709506.254390@p10g2000cwp.googlegroups .com>,
> > oneders <oneders@gmail.com> wrote:
> > >Hey guys..
> > >another question
> > >Which one is better: symmetric key algorithm or asymmetric key
> > >algorithm and why?
> >
> > That is covered in any good encryption textbook such as "Applied
> > Cryptography", and can probably easily be googled up.
> >
> > The answer, by the way, is "Neither is better, but either is better
> > than nothing."
>
> A simple answer could be: asymmetric encryption is usually more secure,
> but also significantly slower.
>
The security of an encryption algorithm depends solely on two things:
the length of the key and the strength of the resistance of the
algorithm to cryptanalysis. There is nothing in principle that makes
asymmetric algorithms more secure than symmetric algorithms. In fact,
one might argue that asymmetric algorithms are somewhat less secure
because the cryptanalyst can generate an unlimited number of
plaintext-ciphertext pairs to work with, whereas this is usually not
possible with symmetric algorithms.

Bill Stallings


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In article <020320061715258677%somebody@somewhere.net>,
<somebody@somewhere.net> wrote:

> In article <barmar-3AADD2.23045801032006@comcast.dca.giganews.com>,
> Barry Margolin <barmar@alum.mit.edu> wrote:
>
> > In article <k2jNf.82228$sa3.63791@pd7tw1no>,
> > roberson@hushmail.com (Walter Roberson) wrote:
> >
> > > In article <1141197605.709506.254390@p10g2000cwp.googlegroups .com>,
> > > oneders <oneders@gmail.com> wrote:
> > > >Hey guys..
> > > >another question
> > > >Which one is better: symmetric key algorithm or asymmetric key
> > > >algorithm and why?
> > >
> > > That is covered in any good encryption textbook such as "Applied
> > > Cryptography", and can probably easily be googled up.
> > >
> > > The answer, by the way, is "Neither is better, but either is better
> > > than nothing."
> >
> > A simple answer could be: asymmetric encryption is usually more secure,
> > but also significantly slower.
> >
> The security of an encryption algorithm depends solely on two things:
> the length of the key and the strength of the resistance of the
> algorithm to cryptanalysis. There is nothing in principle that makes
> asymmetric algorithms more secure than symmetric algorithms. In fact,
> one might argue that asymmetric algorithms are somewhat less secure
> because the cryptanalyst can generate an unlimited number of
> plaintext-ciphertext pairs to work with, whereas this is usually not
> possible with symmetric algorithms.

True -- I was implicitly presuming comparable key strength.

Also, the decreased security of symmetric encryption comes from the need
to distribute the keys in the first place. The more places the key is
stored, the more possibility of it being stolen.

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***

In article <020320061715258677%somebody@somewhere.net>,
<somebody@somewhere.net> wrote:

>The security of an encryption algorithm depends solely on two things:
>the length of the key and the strength of the resistance of the
>algorithm to cryptanalysis.

But the algorithm is only one portion of the matter. The security
of the keys and the security of the key distribution mechanism
are also important, and those differ between different kinds
of encryption algorithms.