Patent ID: 6937726
Filing Date: 2005-08-30
Classification: H04L

Abstract:
1. A method for protecting a data file on a computer system, comprising the steps of: providing a grantee's encryption key, a grantee's decryption key, a grantor's encryption key, and a grantor's decryption key; using asymmetric encryption, encrypting the data file using the grantor's encryption key to create an encrypted data file; generating a transformation key from the grantor's decryption key, the grantee's encryption key and other data which is data file independent; transforming the encrypted data file with the transformation of the encrypted data file does not reveal the data file during the process of transforming; providing the transformed encrypted data file to the grantee; and decrypting the transformed encrypted file by the grantee with the grantee's decryption key; wherein the transformation key does not allow the grantee to determine the grantor's decryption key.