Authentication chip with protection from power supply attacks

• US 6,745,331 B1
• Filed: 03/02/2000
• Issued: 06/01/2004
• Est. Priority Date: 07/10/1998
• Status: Expired due to Fees

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Morse, Gregory
• Assistant Examiner(s): Lipman, Jacob
• Application Number:
  US09/516,874
• Time in Patent Office: 1,552 Days
• Field of Search: 138/36, 713/200
• US Class Current: 726/36
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/77 in smart cards
• CPC Class Codes: G06F 2221/2103 Challenge-response
• CPC Class Codes: G06F 2221/2129 Authenticate client device independently of the user
• CPC Class Codes: G06F 2221/2143 Clearing memory, e.g. to prevent the data from being stolen
• CPC Class Codes: H04L 2209/043 of tables, e.g. lookup, substitution or mapping
• CPC Class Codes: H04L 2209/08 Randomization, e.g. dummy operations or using noise
• CPC Class Codes: H04L 9/002 Countermeasures against attacks on cryptographic mechanisms network architectures or network communication protocols for protection against malicious traffic H04L63/1441
• CPC Class Codes: H04L 9/3218 using proof of knowledge, e.g. Fiat-Shamir, GQ, Schnorr, ornon-interactive zero-knowledge proofs
• CPC Class Codes: H04L 9/3242 involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC
• CPC Class Codes: H04L 9/3271 using challenge-response

Abstract

This invention concerns an authentication chip including an OverUnderPower detection unit to prevent power supply attacks. The unit comprises: a first comparator to detect voltage rises above a predetermined limit, and a second comparator connected to detect voltage drops below a predetermined limit. The output provides a RESET signal to clear all volatile memory in the chip in the event of the power supply voltage exceeding the predetermined limits.

Claims

1. An authentication chip including a volatile memory for containing an authentication key and further including a detection unit to prevent power supply attacks, the detection unit comprising:

a first comparator having a first input connected to a reference voltage and a second input connected to a power supply line to detect power supply voltage rises above a predetermined limit, and a second comparator having a first input connected to the reference voltage and a second input connected to the power supply line to detect power supply voltage drops below a predetermined limit, and an output to provide a signal to clear said volatile memory, in the event of the power supply voltage being outside the predetermined limits.

2. An authentication chip according to claim 1, where the detection unit is connected into a tamper detection line, the tamper detection line responding to the signal to clear all volatile memory in the authentication chip.

3. An authentication chip according to claim 1, where the detection unit is implemented in CMOS.

4. An authentication chip according to claim 1, where the detection unit is covered by a tamper detection line, or by a tamper prevention line, or both.