RE: Diffle-Hellman Exchange Question [7:27952]

2001-12-04 Thread [EMAIL PROTECTED]

With RSA you have to consider public key cryptography concepts. Only
the public key will get public, the secret one (basically used to
decrypt what the public key encrypted) stays with the peer.

The "problem" here is that public key cryptography needs huge keys to
be secure, what inhibits to use them to encrypt large amount of data.
Usually RSA is used to exchange the symetric keys (shorter keys) that
will be used to encrypt the actual data. AFAIK, DH is just a key
exchange protocol.

You can also sign some informatios, that is basically the reverse of
encrypt. Because the secret key is used to encrypt, and the public key
to decrypt. So, the remote peer can be sure that the packet came from
who owns the secret key.

With RSA you can also sign packets using a third party (a CA) that
both peers agree with and trust. 


-Original Message-
From: Hunt Lee [mailto:[EMAIL PROTECTED]]
Sent: terca-feira, 4 de dezembro de 2001 09:31
To: [EMAIL PROTECTED]
Subject: Re: Diffle-Hellman Exchange Question [7:27952]


Thanks for the URL.  However, why does Cisco says:

With the Diffie-Hellman exchange, the DES key never crosses the
network (not
even in encrypted form), "which is not the case with the RSA encrypt
and
sign technique." - so what about RSA encrypt and sign technique?  I'm
very
confused...

Thanks again.

Hunt


 wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Alex, your are 100% correct.
>
> Whitfield & Martin (using modular arithmetic) found a beautiful
> algorithm in which partners agree in a same key exchanging part of
> his/her initial secret key. Never the key will be exchanged in the
> public network. As the key is the same for both partners, it is good
> for symetric encryption (fast) like DES.
>
>
> -Original Message-
> From: Alex Lei [mailto:[EMAIL PROTECTED]]
> Sent: segunda-feira, 3 de dezembro de 2001 16:12
> To: [EMAIL PROTECTED]
> Subject: RE: Diffle-Hellman Exchange Question [7:27952]
>
>
> Hello Hunt,
>
> In my understanding the shared key never go across the network. Each
> peer
> computes it out separately. Where did you see in CCO saying that the
> DES key
> is sent across the internet?
>
> Alex




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Re: Diffle-Hellman Exchange Question [7:27952]

2001-12-04 Thread Hunt Lee

Thanks for the URL.  However, why does Cisco says:

With the Diffie-Hellman exchange, the DES key never crosses the network (not
even in encrypted form), "which is not the case with the RSA encrypt and
sign technique." - so what about RSA encrypt and sign technique?  I'm very
confused...

Thanks again.

Hunt


 wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Alex, your are 100% correct.
>
> Whitfield & Martin (using modular arithmetic) found a beautiful
> algorithm in which partners agree in a same key exchanging part of
> his/her initial secret key. Never the key will be exchanged in the
> public network. As the key is the same for both partners, it is good
> for symetric encryption (fast) like DES.
>
>
> -Original Message-
> From: Alex Lei [mailto:[EMAIL PROTECTED]]
> Sent: segunda-feira, 3 de dezembro de 2001 16:12
> To: [EMAIL PROTECTED]
> Subject: RE: Diffle-Hellman Exchange Question [7:27952]
>
>
> Hello Hunt,
>
> In my understanding the shared key never go across the network. Each
> peer
> computes it out separately. Where did you see in CCO saying that the
> DES key
> is sent across the internet?
>
> Alex




Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=28051&t=27952
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RE: Diffle-Hellman Exchange Question [7:27952]

2001-12-03 Thread [EMAIL PROTECTED]

Alex, your are 100% correct.

Whitfield & Martin (using modular arithmetic) found a beautiful
algorithm in which partners agree in a same key exchanging part of
his/her initial secret key. Never the key will be exchanged in the
public network. As the key is the same for both partners, it is good
for symetric encryption (fast) like DES.


-Original Message-
From: Alex Lei [mailto:[EMAIL PROTECTED]]
Sent: segunda-feira, 3 de dezembro de 2001 16:12
To: [EMAIL PROTECTED]
Subject: RE: Diffle-Hellman Exchange Question [7:27952]


Hello Hunt,

In my understanding the shared key never go across the network. Each
peer
computes it out separately. Where did you see in CCO saying that the
DES key
is sent across the internet?

Alex




Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=28017&t=27952
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RE: Diffle-Hellman Exchange Question [7:27952]

2001-12-03 Thread Alex Lei

I have a link here for your reference. Read the section on RSA.

http://www.cisco.com/warp/public/105/IPSECpart3.html


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RE: Diffle-Hellman Exchange Question [7:27952]

2001-12-03 Thread Alex Lei

Hello Hunt,

In my understanding the shared key never go across the network. Each peer
computes it out separately. Where did you see in CCO saying that the DES key
is sent across the internet?

Alex


Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=27998&t=27952
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