Patent ID: 7657760

Claim:
A method for sharing an encrypted data region among first and second processes on a tamper resistant processor having a program and a data encryption/decryption function, the method comprising: (a) shifting an execution mode of the tamper resistant processor to an encrypted instruction execution mode; (b) operating the first process to generate a first hidden region of the first process and the second process to generate a second hidden data region of the second process and to specify a first key for the first hidden data region of the first process in a first process space of the first process and to specify a second key for the second hidden data region of the second process in a second process space of the second process under the encrypted instruction execution mode, the first key being different from the second key; (c) operating the first and second processes to generate mutually different key pairs to be used in a key exchange and carrying out the key exchange between the first and second processes; (d) operating each of the first and second processes to generate a common key according to the key exchange; (e) generating a shared encrypted data region to be shared by the first and second processes which is valid only with respect to the common key; and (f) storing the common key and data used in a course of the key exchange in the first hidden data region of the first process and in the second hidden data region of the second process, which are valid only with respect to the first key for the first hidden data region and the second key for the second hidden data region.