Method for securing DOCSIS cable modem against physical security attacks

1. A method for securing a cable modem (CM) following Data Over Cable Service Interface Specification (DOCSIS) against physical security attacks, comprising the steps of:

a) classifying information to be stored in the DOCSIS CM based on a requirement degree of confidentiality and anti-alteration;

b) storing the classified information in a non-volatile memory of the DOCSIS CM when the information is absolute confidential information, but processing a mechanism for deleting the information stored in the non-volatile memory in case that attacks by a hacker is sensed;

c) storing the classified information in the non-volatile memory of the DOCSIS CM when the information is middle-level security information; and

d) storing the classified information in a write-once (WO) memory of the DOCSIS CM when the information is absolute anti-alteration information, wherein a security level of the absolute anti-alteration information does not exceed level 1 of the Federal Information Processing Standards Publication 140-2 (FIPS PUB 140-2).

2. The method as recited in claim 1 , further comprising the step of:

e) checking integrity of the absolute anti-alteration information stored in the WO memory whenever the DOCSISCM turns on.

3. The method as recited in claim 2 , wherein it is checked in the step e) whether the absolute anti-alteration information is changed as regulated in FIPS PUB 140-2 “4.9.1. Power-up Test” whenever the power of the DOCSISCM turns on.

4. The method as recited in claim 3 , wherein the absolute confidential information includes a DOCSIS CM' Rivest-Shamir-Adelman (RSA) private/public key pair, a CableLabs' or Manufacturer's RSA public key and Critical Security Parameter (CSP); the middle-level security information includes a CableLabs' or manufacturer's certificate; and the absolute anti-alteration information includes CM's certificate and boot-loader.

5. A method for securing cable modem (CM) following a Data Over Cable Service Interface Specification (DOCSIS) against physical security attacks, comprising the steps of:

a) classifying information to be stored in the DOCSIS CM based on a requirement degree of confidentiality and anti-alteration;

b) storing the classified information in a non-volatile memory of the DOCSIS CM by performing key encapsulation on the information when the information to be stored is absolute confidential information;

c) storing the classified information in the non-volatile memory of the DOCSIS CM when the information is middle-level security information; and

d) storing the classified information in a write-once (WO) memory of the DOCSIS CM when the information is absolute anti-alteration information.

6. The method as recited in claim 5 , further comprising the step of:

e) checking integrity of the absolute anti-alteration information stored in the WO memory whenever the DOCSISCM turns on.

7. The method as recited in claim 6 , wherein it is checked in the step e) whether the absolute anti-alteration information is changed as regulated in FIPS PUB 140-2 “4.9.1. Power-up Test” whenever the power of the DOCSISCM turns on.

8. The method as recited in claim 7 , wherein the absolute confidential information includes a DOCSIS CM' Rivest-Shamir-Adelman (RSA) private/public key pair, a CableLabs' or Manufacturer's RSA public key and Critical Security Parameter (CSP); the middle-level security information includes a CableLabs' or manufacturer's certificate; and the absolute anti-alteration information includes CM's certificate and boot-loader.