Secret Sharing: Difference between revisions

From
Jump to navigation Jump to search
Content deleted Content added
Henryk (talk | contribs)
No edit summary
 
Henryk (talk | contribs)
No edit summary
Line 2: Line 2:


== A Simple Approach ==
== A Simple Approach ==
One simple approach to split a secret number <math>D</math> into <math>n</math> pieces <math>D_1, D_2, \ldots, D_n</math> such that any <math>k</math> pieces are sufficient (and necessary) to reconstruct <math>D</math> is using a <math>k-1</math> polynomial.
One simple approach to split a secret number <math>D</math> into <math>n</math> pieces <math>D_1, D_2, </math>…<math>, D_n</math> such that any <math>k</math> pieces are sufficient (and necessary) to reconstruct <math>D</math> is using a <math>k-1</math> polynomial.


When splitting the secret a random polynomial <math>f(x) = a_0 + a_1 \cdot x + a_2 \cdot x + \ldots a_{k-1} x^{k-1}</math> with <math>a_0 = D</math> is generated. The <math>D_i</math> are calculated as <math>D_i = f(i) \mbox{ for } i = 1, \ldots, n</math>.
When splitting the secret a random polynomial <math>f(x) = a_0 + a_1 x + a_2 x + </math>…<math> + a_{k-1} x^{k-1}</math> with <math>a_0 = D</math> is generated. The <math>D_i</math> are calculated as <math>D_i = f(i)</math> for <math>i = 1, </math>…<math>, n</math>.


Given any <math>k</math> <math>D_i</math> it is possible to interpolate the polynomial and calculate <math>f(0)</math> which gives the original secret <math>D</math>.
Given any <math>k</math> <math>D_i</math> it is possible to interpolate the polynomial and calculate <math>f(0)</math> which gives the original secret <math>D</math>.

Revision as of 10:33, 1 December 2004

Secret Sharing is used to split a secret (usually a key) into several pieces which are then given to distinct persons so that some of these persons must cooperate to reconstruct the secret.

A Simple Approach

One simple approach to split a secret number D into n pieces D1,D2,,Dn such that any k pieces are sufficient (and necessary) to reconstruct D is using a k1 polynomial.

When splitting the secret a random polynomial f(x)=a0+a1x+a2x++ak1xk1 with a0=D is generated. The Di are calculated as Di=f(i) for i=1,,n.

Given any k Di it is possible to interpolate the polynomial and calculate f(0) which gives the original secret D.