Browse Prior Art Database

Anti-Clone Design for Cellular Phone

IP.com Disclosure Number: IPCOM000004772D
Original Publication Date: 2001-May-11
Included in the Prior Art Database: 2001-May-11
Document File: 4 page(s) / 37K

Publishing Venue

Motorola

Related People

Yung Weng Fan: AUTHOR [+2]

Abstract

Phone cloning and modification has been problem for cellular telephone manufacturers. Cellular telephone market segmentation and price discrimination strategies affect the prices that can vary greatly in different regions and countries. Typically, distributors buy cheaper phones in one market (e.g., Europe) and export them to an alternative market (e.g., China) that has higher selling price. The cellular telephones are sold in the alternative market after modification to support local languages. In China, this is achieved by inserting an Asian Character Font Memory chip (CGROM) and thereafter effecting software reconfiguration to support the CGROM..

This text was extracted from a Microsoft Word 97 document.
This is the abbreviated version, containing approximately 71% of the total text.

Anti-Clone Design for Cellular Phone

By

Yung Weng Fan and Se Toh Wai Tuck.

Abstract

Phone cloning and modification has been problem for cellular telephone manufacturers. Cellular telephone market segmentation and price discrimination strategies affect the prices that can vary greatly in different regions and countries. Typically, distributors buy cheaper phones in one market (e.g., Europe) and export them to an alternative market (e.g., China) that has higher selling price. The cellular telephones are sold in the alternative market after modification to support local languages. In China, this is achieved by inserting an Asian Character Font Memory chip (CGROM) and thereafter effecting software reconfiguration to support the CGROM..

Detailed Description of a new Anti-Clone Design

Two existing hardware components are used in this anti-cloning design. They are the IIM (IC Identification Module) and the Protection Register. The IIM consists of a 128-bits Unique ID register that is programmed to a unique value (UID) for each die produced. It is laser permanently programmed in the factory. The IIM module is embedded in a Baseband IC. The IIM is readable by the cellular telephone's MCU. The protection register is a 64-bits, lockable register in Flash memory.

An overview of the design is shown in figure 1. A key generation process is implemented to generate a new 128-bits unique key from the UID (IIM). The new key is used to identify the type of fonts (CGROM) supported by the phone. This new key is referred to as the Font Identification Key. A Font Identification Key generator can either be an encryption, convolution, or an orthogonal process. The objective is to create a unique and hidden key for each cellular telephone. Since each telephone has its own Font Identification Key, it will be difficult to crack. The UID (IIM) can be read by the MCU and is not used as the Font Identification Key directly.

Depending on the font type (or font group), part of the Font Identification Key is duplicated and stored in the Protection Register of the Flash. The protection register is locked immediately to protect it from erasure and modification. Since the Protection Register is 64-bits wide, the partial key will be of the same length to maximise the number of combinations. The partial key can be the upper or lower 64-bits, or even bits, or odd bits, or some other bit selection dependent on the type of languages supported. This process is implemented in the Partial Key Extractor.

When the phone is powered up, it calculates the Font Identification Key using the UID (IIM). Then, it checks for the type of languages supported by the phone. Depending on the type of languages supported, the phone extracts the appropriate partial key and verifies it against with the one that is stored in the Protection register of the Flash memory. If there is no match, the phone will power down; else, the check verifies that the phone has not been modified by an unauthorized source and a normal pow...