Patent ID: 6748084
Filing Date: 2004-06-08
Classification: H04L

Abstract:
A method for data access control, wherein a master key is used to control data access in a data storage device when the data storage device is requested to be accessed, the method comprising:dividing the master key into n initial subkeys which are kept separately, wherein a (m,n)-threshold scheme is used, and m is a natural number larger than 1 but smaller than n an initial subkey i of the n initial subkeys is kept by a subkey holder i and i =1, . . . , n; using a master key reconstruction procedure to reconstruct the master key according to m packaged subkeys when the m packaged subkeys are received from m of the n subkey holders, comprising the steps of: sending a code based on a polynomial g(x) and a random number k from the master key reconstruction procedure to the n subkey holders, wherein the polynomial g(x) is a pre-shared secret of the n subkey holders and the master key reconstruction procedure, and the random number k is generated when the data storage device is requested to be accessed; and receiving the m packaged subkeys from m of the n subkey holders, wherein m is smaller than n, and each of the m packaged subkeys is based on a sum of a first polynomial and a second polynomial, where the first polynomial is based on the respective initial subkey kept by the subkey holder and the second polynomial is based on the code, the random number, and a shared secret d which is a shared secret between the n subkey holders and the master key reconstruction procedure; and using the master key to encrypt and decrypt data of the data storage device while said data is desired to be accessed.