# Re: EC Key Derivation Problem

*From*: Kristian Gjøsteen <kristiag+news@xxxxxxxxxxxx>*Date*: Sat, 15 Mar 2008 15:14:15 +0000 (UTC)

Fabrice <fabrice.gautier@xxxxxxxxx> wrote:

Examples:

You have a set of systems with the same Private Key (a) inside. If

you want to encrypt something for any of the system you use the Public

Key (A). Now, each system has a different Serial Number ("k"). You

want to encrypt something for one system only so you encrypt with B.

You are looking for identity-based cryptography. Your solution is too

simple, I'm afraid. If the serial number is public, it suffers from

an insider attack. If the serial number isn't public, you could just

as well use two different public keys, so what's the point?

--

Kristian Gjøsteen

.

**Follow-Ups**:**Re: EC Key Derivation Problem***From:*Fabrice

**References**:**EC Key Derivation Problem***From:*Fabrice

**Re: EC Key Derivation Problem***From:*Kristian Gjøsteen

**Re: EC Key Derivation Problem***From:*Fabrice

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