RE: integrity and mail encryption

["Adrian Floarea" <adrian.floarea () uti ro>]

Yes, you need a certification authority for that.  But, this is a problem of
trust.

As far as I know a public key infrastructure (technical terms) implies and a
certification authority. 

More details about this you can find on this link
http://csrc.nist.gov/pki/PKIResearch.html

I hope to help you.

Regards,

Adi Floarea

-----Original Message-----
From: Pranav Lal [mailto:pranav.lal () gmail com] 
Sent: Saturday, November 05, 2005 6:03 PM
To: security-basics () securityfocus com
Subject: RE: integrity and mail encryption

Hi Adrian,

How do you establish ownership of a private key? As others have said you
need a certifying authority to establish this so a public key
infra-structure by itself does not provide non-repudiation.

Pranav
on Friday 11/4/2005 02:40 PM, Adrian Floarea said:

In fact the public key digital signature provide non-repudiation which means
that only the person which has the corresponding private key can make a
digital signature. Shortly, the process is: you have a private key and a
public key. The private key is secret. When you make a digital signature,
first you make a hash of electronic data and after that, you encrypt this
hash with your private key. When someone wants to verify your signature,
make again the hash on the data, decrypt the original hash using your public
key and after that, compare them. Because, you are the only person which has
the private key, you can't deny that you are the person who make the
original digital signature.

Actually the process is much complicated, but the essence is that what I
explain bottom.

Regards,

Security Product Team Leader
Adrian Floarea, CISA
Information Security Department
Bucharest, Romania
Email: adrian.floarea () uti ro







-----Original Message-----
From: Pranav Lal [mailto:pranav.lal () gmail com]
Sent: Wednesday, November 02, 2005 11:21 PM
To: security-basics () securityfocus com
Subject: RE: integrity and mail encryption

Hi Bob,

How does public key encryption provide                  non-repudiation


Pranav