Volatile device keys and applications thereof

• US 7,564,345 B2
• Filed: 11/14/2005
• Issued: 07/21/2009
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Verayo, Inc.
• Original Assignee: Verayo, Inc.
• Inventors: Devadas, Srinivas, Ziola, Thomas
• Primary Examiner(s): Pham; Toan N
• Assistant Examiner(s): Hunnings; Travis R
• Application Number:
  US11/273,920
• Publication Number:
  US 20060210082A1
• Time in Patent Office: 1,345 Days
• Field of Search: 340/572, 340/10, 340/505, 713/200, 713/181, 713/189
• US Class Current: 340/539.1
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/445 by mutual authentication, e.g. between devices or programs
• CPC Class Codes: G06F 21/602 Providing cryptographic facilities or services
• CPC Class Codes: G06F 21/76 in application-specific integrated circuits [ASIC] or field-programmable devices, e.g. field-programmable gate arrays [FPGA] or programmable logic devices [PLD]
• CPC Class Codes: G06F 2221/2129 Authenticate client device independently of the user
• CPC Class Codes: G11C 16/20 Initialising; Data preset; Chip identification
• CPC Class Codes: G11C 16/22 Safety or protection circuits preventing unauthorised or accidental access to memory cells
• CPC Class Codes: G11C 2029/4402 Internal storage of test result, quality data, chip identification, repair information
• CPC Class Codes: G11C 2029/5002 Characteristic
• CPC Class Codes: G11C 7/24 Memory cell safety or protection circuits, e.g. arrangements for preventing inadvertent reading or writing; Status cells; Test cells
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 9/0838 Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these network architectures or network communication protocols for key exchange in a packet data network H04L63/061
• CPC Class Codes: H04L 9/0877 using additional device, e.g. trusted platform module [TPM], smartcard, USB or hardware security module [HSM]
• CPC Class Codes: H04L 9/304 based on error correction codes, e.g. McEliece
• CPC Class Codes: H04L 9/3278 using physically unclonable functions [PUF]

Abstract

A key is determined from a volatile response using circuitry on the device. The volatile response depend on process variation in fabrication of the device. Error control data that depends on the first volatile response can be computed, stored externally to the device, and then used to generate the key using a volatile response using the circuit. Applications of volatile keys include authentication and rights management for content and software.

Claims

1. A proximity device comprising:

a radio interface providing remote access to information stored persistently on the device, and to circuitry for generating a volatile response on the device;

a storage for persistent information coupled to the radio interface for storing persistent values on the device;

circuitry coupled to the radio interface for generating a volatile response, wherein the circuitry for generating the volatile response includes

a signal delay component configurable to form a plurality signal delay paths, each delay path being configurable such that a signal propagation characteristic of the delay path depends on at least one of a persistent value stored in the device and a challenge value received at the device over the radio interface, the signal propagation characteristic of the delay path depending on fabrication characteristics of the device that are substantially unique to the device from amongst other devices fabricated according to a common design,

a comparison component coupled to the signal delay component, for comparing the signal propagation characteristics of multiple of the signal delay paths, and

an accumulation component coupled to the comparison component for accumulating values output from the comparison component to determine the volatile response.