DOCSLIB.ORG

An Introduction to Keeloq Code Hopping

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
An Introduction to Keeloq Code Hopping TB003 An Introduction to KEELOQ® Code Hopping Author: Kobus Marneweck A remote control transmitter of the type normally used Microchip Technology Inc. in vehicle security systems, is nothing but a small radio transmitter that transmits a code number on a certain frequency. This code number is normally generated by INTRODUCTION an integrated circuit encoder. The transmit frequency is normally fixed by legislation within a particular country, Remote Control Systems enabling anybody to build a simple receiver that can Remote control via RF or IR is popular for many appli- receive signals from all such transmitters. cations, including vehicle alarms and automatic garage It is a simple matter to build a circuit to record such doors. Conventional remote control systems are based transmissions captured by the receiver. Such a device on unidirectional transmission and have limited secu- is known as a code or key grabber. A would-be vehicle rity. More sophisticated devices based on bi-directional thief would typically lurk in a parking lot, waiting until a transmission are also available but, because of their vehicle owner arms his alarm with a remote control. high cost and certain practical disadvantages, they are The key grabber would capture the transmitted code, not widely used in commercial remote control devices. enabling the thief to retransmit this code as soon as the The popular unidirectional transmission systems cur- owner leaves the parking lot. Typically, this would leave rently have two very important security shortcomings: the alarm and/or immobilizer disabled and even the the codes they transmit are usually fixed and the num- central locking unlocked. ber of possible code combinations is relatively small. The Solution Either of these shortcomings can lead to unauthorized It is apparent that secure remote control systems can access. only be implemented if two conditions are met. The Code Scanning KEELOQ® code hopping system meets both these con- The limited number of possible combinations available in ditions with ease. most remote control systems makes it possible to trans- • A large number of possible combinations must be mit all possible combinations in a relatively short time. A available. hand held microprocessor-based system for this pur- A 66-bit transmission code is used to make scan- pose (called a code scanner) can easily be constructed. ning impossible. The 32-bit encrypted portion pro- In systems using eight DIP switches (256 combina- vides for more than 4 billion code combinations. A tions), this scanning process can typically be accom- complete scan would take 17 years! If the 34-bit plished in less than 32 seconds (when trying eight fixed portion is taken into account, the time combinations per second). Even in systems using required for a complete scan jumps to 5,600 bil- 16-bit keys (yielding roughly 65,000 combinations), lion years! only 2.25 hours would be required to try all possible • The system may never respond twice to the same combinations. It should also be noted that the scanner transmitted code. may gain access in far less than this maximum time— The random code algorithm will never respond to the average time would in fact be half of the total time. the same code twice over several lifetimes of a Scanning is counteracted by increasing the number of typical system. possible code combinations. A 66-bit code will yield Every time a remote control button is pushed, the sys- 19 11 7.3 x 10 combination and will take 2.3 x 10 years to tem will transmit a different code. These codes appear scan. random to an outsider – there is no apparent relation- Code Grabbing ship between any code and the previous or next code. A far easier way of gaining unauthorized access to a security system is freely available—such a unit is being advertised as a tool for the “legal repossession of vehi- cles.” To understand its operation, it is useful to know something about remote controls. KEELOQ is a registered trademark of Microchip Technology, Inc. Microchip’s Secure Data Products are covered by some or all of the following patents: Code hopping encoder patents issued in Europe, U.S.A., and R.S.A. — U.S.A.: 5,517,187; Europe: 0459781; R.S.A.: ZA93/4726 Secure learning patents issued in the U.S.A. and R.S.A. — U.S.A.: 5,686,904; R.S.A.: 95/5429 Ó 1996 Microchip Technology Inc. DS91002A-page 1 TB003 Once the system has responded to a valid code, about encoding) differs only in one bit from the information in 65,000 valid codes will have to be received before the the previous transmission, the next transmission will be same code will be used again. If the remote control is totally different. used eight times daily, 22 years will pass before the Checks exist that can be used to verify the security system responds to the same code again - once! characteristics of an encoding algorithm and, in this Therefore, a retransmitted code (like when a code instance, to determine whether the next transmitted grabber is used) will never activate the system. code is predictable to any degree. The Avalanche The KEELOQ algorithm also features sophisticated syn- Effect and a subset thereof, the Strict Avalanche Crite- chronization techniques. The system will continue to rion, have been tested on the KEELOQ algorithm. The function even if the transmitter is activated repeatedly results give a good indication of the security offered by while not in range of the receiver (as would happen if a the system. child played with the remote control). If a button is • Avalanche Effect (AE) pressed out of range more than 16 times, synchroniza- A block cipher satisfies the AE if changing one bit tion will be lost. However, two successive transmis- of the information causes, on average, half of the sions in range will restore synchronization. When no bits in the transmission to change. In the KEELOQ response occurs to a transmitter operation, the user's algorithm, this implies that changing one bit in the natural reaction is to press the button a second time. function and/or synchronization information will Synchronization will be restored when he does. Opera- cause an average of 16 of the 32 bits in the trans- tion is totally transparent — the user may not even mitted code to change. become aware that synchronization has been lost and restored. • Strict Avalanche Criterion (SAC) The SAC requires that, if one bit of the encoded These obvious security benefits are attainable at a cost information is changed, each bit in the output comparable to existing fixed code systems. The revolu- must have a chance of 0.5 of changing as well. tionary nature of the KEELOQ algorithm, full custom IC Consequently, the probability of guessing any one implementation, and reduced external component bit correctly is 0.5, and the probability of guessing requirements help to make this level of cost effective- an entire 32-bit string correctly is one in about ness possible. 4,300,000,000! The KEELOQ Algorithm The tests involved using a random 64-bit key and KEELOQ is a proprietary block cipher based on a block a Gray counter (starting at zero) as input to the length of 32 bits and a key length of 64 bits. The algo- algorithm. In each case, the output was compared rithm is characterized by a very economical hardware with a reference (SAC) or with the previous code implementation, while retaining a level of security com- (AE). In both cases, the results were as expected: parable to Data Encryption Standards (DES). This level For the AE, the average number of bits changed of security makes it eminently suitable for code commu- was 16.0 (50%), with a standard deviation of 2.83 nication applications such as code hopping antitheft or (8.8%). For the SAC, each individual bit changed access control devices. an average of 50% of the time, with a standard deviation of 8.8%. Information regarding transmitter identity and synchro- nization is encoded so as to render it unintelligible to an outsider. For decoding, it is necessary to have the same 64-bit key originally used for encoding. There- fore, even though the decoder (which has the key) can identify the transmitter unambiguously, an outsider (who does not have access to the key and/or the algo- rithm) can glean no information at all from the transmis- sions. As it is impossible to insert information into the system from outside, strategies used to attack FEAL and other DES-like ciphers are not usable against this system. The KEELOQ algorithm is designed to make it impossi- ble for a potential assailant to predict the next code that will be transmitted by a valid transmitter. Even if the assailant makes a reasonable guess regarding the way in which transmitted information changes with each transmission, the algorithm obscures this information sufficiently that the next code can not be anticipated. In particular, even if the transmitted information (before DS91002A-page 2 Ó 1996 Microchip Technology Inc. TB003 DEFINITIONS USED IN CODE HOPPING Transmitter Serial Number Each transmitter is programmed with a unique 28- or 32-bit serial number at the time of transmitter manufacture. This ensures that each transmitter will be unique within a system. Secret Key This 64-bit secret key is generated by a key generation function from the 28- or 32-bit serial number or the 32- or 48-bit seed and 64-bit manufacturer's key as inputs. A manufacturer’s key can be used to control the key generation func- tion. The secret key is not readable and is never transmitted.
Load more

Recommended publications
  • Application of KEELOQ Algorithm in PEPS System
    International Conference on Education, Management, Computer and Society (EMCS 2016) Application Of KEELOQ Algorithm In PEPS System Dan Li Yi Wang1,2 * Dept. of Physics & Electronic Science Guizhou Normal University 1.Key Laboratory of special Automotive Electronics Guiyang,Guizhou,China technology of the Education Department of Guizhou e-mail:[email protected] Province Guiyang, Guizhou, China 2. Dept.of Physics & Electronic Science,Guizhou 1,2 Wen jun Xiao Normal University 1.Key Laboratory of special Automotive Electronics Guiyang,Guizhou,China e-mail:[email protected] technology of the Education Department of Guizhou Province *Corresponding Author Guiyang,Guizhou,China 2. Dept.of Physics & Electronic Science,Guizhou Normal University Guiyang,Guizhou,China e-mail:[email protected] Abstract—Passive Entry Passive Start(PEPS) because its system is developed on the basis of the remote access high security and easy to use which has become the main system is the latest security technology,it integrates the development trend in the field of the automotive remote access system and anti-theft lock check system electronics.For the security and reliability of PEPS (Immobilizer, IMMO) function,to a great extent,it satisfies system,my paper proposed a encryption and decryption the people to the requirements of access control system method based on KEELOQ algorithm.Compared with other security, The KEELOQ algorithm proposed in this paper to encryption algorithms,the proposed method increases the implement the encryption and decryption of PEPS system, synchronization,which
    [Show full text]
  • Optimization and Guess-Then-Solve Attacks in Cryptanalysis
    Optimization and Guess-then-Solve Attacks in Cryptanalysis Guangyan Song A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy of University College London. Department of Computer Science University College London December 4, 2018 2 I, Guangyan Song, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the work. Abstract In this thesis we study two major topics in cryptanalysis and optimization: software algebraic cryptanalysis and elliptic curve optimizations in cryptanalysis. The idea of algebraic cryptanalysis is to model a cipher by a Multivariate Quadratic (MQ) equation system. Solving MQ is an NP-hard problem. However, NP-hard prob- lems have a point of phase transition where the problems become easy to solve. This thesis explores different optimizations to make solving algebraic cryptanalysis problems easier. We first worked on guessing a well-chosen number of key bits, a specific opti- mization problem leading to guess-then-solve attacks on GOST cipher. In addition to attacks, we propose two new security metrics of contradiction immunity and SAT immunity applicable to any cipher. These optimizations play a pivotal role in recent highly competitive results on full GOST. This and another cipher Simon, which we cryptanalyzed were submitted to ISO to become a global encryption standard which is the reason why we study the security of these ciphers in a lot of detail. Another optimization direction is to use well-selected data in conjunction with Plaintext/Ciphertext pairs following a truncated differential property.
    [Show full text]
  • The Analysis and Improvement of KEELOQ Algorithm
    International Journal of Computer Electrical Engineering The Analysis and Improvement of KEELOQ Algorithm Dan Li*, Wenjun Xiao, Ziyi You, Yi Wang Dept. of Physics & Electronic Science, Guizhou Normal University, Guiyang, China. Corresponding author. Tel.:18583510456; email: [email protected] Manuscript submitted July 17, 2017; accepted August 28, 2017. doi: 10.17706/ijcee.2017.9.2.439-444 Abstract: Block cipher is used widely, as byte-orientation differential, cryptanalysis and linear cryptanalysis of block cipher, which is the security fatal blow. The KEELOQ algorithm is a block cipher algorithm designed by South Africa Willem Smit in the 1980s,in this thesis, based on the summary of the previous attack researches and the detailed rationale of KEELOQ algorithm, taking example by 3DES algorithm, the triple KEELOQ algorithm was proposed, and did the improvement on the key management, this further increased the capture and the difficulty of the crack, improved the safety performance, finally, made an experiments on the paper decode to keeloq, the experimental results show that the algorithm is more safe and more reliable. Key words: Triple KEELOQ algorithm, difference analysis, paper decode. 1. Introduction The KEELOQ algorithm [1] is a block cipher algorithm designed by South Africa Willem Smit in the 1980s, it includes 32-bit block cipher and 64 - bit key length, a block cipher is the nonlinear function of the five variables, it is now widely used in automobiles wireless door lock device. Although the KEELOQ algorithm has been proposed in early, but it was not until 2007 that Bogdanov [2] to use the speculation -decided and sliding technology to attacks the KEELOQ algorithm for the first time, the time complexity of 252,the space complexity of 16 GB.
    [Show full text]
  • Cryptanalysis of Keeloq Code-Hopping Using a Single FPGA
    Cryptanalysis of KeeLoq code-hopping using a Single FPGA Idan Sheetrit and Avishai Wool Computer and Network Security Lab School of Electrical Engineering Tel-Aviv University, Ramat Aviv 69978, Israel [email protected], [email protected] Abstract. The KeeLoq cipher is used in many wireless car door systems and garage openers. Recently the algorithm was studied and several at- tacks have been published. When a random seed is not used the attack on the system is fairly straight-forward. However when a seed is shared between the remote control and the receiver previous research suggested using highly parallel crypto hardware (like COPACOBANA) for break- ing the cipher within reasonable time. In this paper we show that highly-parallel hardware is not necessary: our attack uses a single FPGA for breaking KeeLoq when using a 48-bit random seed in 17 hours using a mid-range Virtex-4, and less than 3 hours using a high-end Virtex-6 chip. We achieve these results using a combination of algorithmic improvements, FPGA design methodology, and Xilinx-specific features. Keywords: KeeLoq, cryptanalysis, FPGA 1 Introduction 1.1 Background Wireless remote controls are popular in many applications including car access and garage door openers. Simple remotes commonly send a unique code on a known frequency to authorize access, which can easily lead to unauthorized ac- cess. A popular improvement is to use the KeeLoq code hopping system: KeeLoq consists of a low cost hardware implementation block cipher which has a large number of combinations available and won't respond twice to same transmitted code.
    [Show full text]
  • KEELOQ® with Advanced Encryption Standard (AES)
    AN1275 ® KEELOQ with Advanced Encryption Standard (AES) Receiver/Decoder KEY FEATURES Author: Enrique Aleman Microchip Technology Inc. The set of modules presented in this application note implement the following features: ® OVERVIEW • Source compatible with HI-TECH C compilers • Pinout compatible with the KEELOQ 3 Develop- This application note describes a KEELOQ® with AES ment Kit code hopping decoder implemented on a Microchip • Normal Learn mode Mid-range Enhanced Flash MCU (PIC16F886). The • Learns up to 8 transmitters, using the internal purpose of this implementation is to demonstrate how EEPROM memory of the PIC® microcontroller KEELOQ code hopping technology can be implemented • Interrupt driven Radio Receive (PWM) routine with the AES encryption algorithm for even greater security. This allows for a higher level of security • Compatible with KEELOQ/AES hopping code solutions for keyless entry systems and access control encoding with PWM transmission format selected, systems. The software has been designed as a group operating at TE = 200 µs. of independent modules written in C. • Automatic synchronization during receive, using the 8 MHz internal oscillator The Advanced Encryption Standard (AES) is a means 2 of encrypting and decrypting data adopted by the •IC™ slave routines are included so that the National Institute of Standards and Technology (NIST) decoder can be designed into a larger control on October 2, 2000. The algorithm used in AES is system. called the Rijndael algorithm after its two designers, • LCD routines are included to display decrypted Joan Daemen and Vincent Rijmen of Belgium. AES is data and messages. a symmetric block cipher that utilizes a secret key to encrypt the data.
    [Show full text]
  • On the Power of Power Analysis in the Real World: a Complete Break of the Keeloq Code Hopping Scheme
    On the Power of Power Analysis in the Real World: A Complete Break of the KeeLoq Code Hopping Scheme Thomas Eisenbarth1, Timo Kasper1, Amir Moradi2,⋆, Christof Paar1, Mahmoud Salmasizadeh2, and Mohammad T. Manzuri Shalmani2 1 Horst Görtz Institute for IT Security Ruhr University Bochum, Germany 2 Department of Computer Engineering and Electronic Research Center Sharif University of Technology, Tehran, Iran {eisenbarth,tkasper,moradi,cpaar}@crypto.rub.de {salmasi,manzuri}@sharif.edu Abstract. KeeLoq remote keyless entry systems are widely used for access control purposes such as garage openers or car door systems. We present the first successful differential power analysis attacks on nume- rous commercially available products employing KeeLoq code hopping. Our new techniques combine side-channel cryptanalysis with specific properties of the KeeLoq algorithm. They allow for efficiently revealing both the secret key of a remote transmitter and the manufacturer key stored in a receiver. As a result, a remote control can be cloned from only ten power traces, allowing for a practical key recovery in few minutes. After extracting the manufacturer key once, with similar techniques, we demonstrate how to recover the secret key of a remote control and repli- cate it from a distance, just by eavesdropping on at most two messages. This key-cloning without physical access to the device has serious real- world security implications, as the technically challenging part can be outsourced to specialists. Finally, we mount a denial of service attack on a KeeLoq access control system. All proposed attacks have been verified on several commercial KeeLoq products. 1 Motivation The KeeLoq block cipher is widely used for security relevant applications, e.g., remote keyless entry (RKE) systems for car or building access, and passive radio frequency identification (RFID) transponders for car immobilizers [13].
    [Show full text]
  • Cryptanalysis of the Keeloq Block Cipher
    Cryptanalysis of the KeeLoq block cipher Andrey Bogdanov Chair for Communication Security Ruhr University Bochum, Germany Abstract. KeeLoq is a block cipher used in numerous widespread pas- sive entry and remote keyless entry systems as well as in various compo- nent identification applications. The KeeLoq algorithm has a 64-bit key and operates on 32-bit blocks. It is based on an NLFSR with a nonlinear feedback function of 5 variables. In this paper a key recovery attack with complexity of about 252 steps is proposed (one step is equivalent to a single KeeLoq encryption opera- tion). In our attack we use the techniques of guess-and-determine, slide, and distinguishing attacks. Several real-world applications are vulnerable to the attack. To our best knowledge this is the first paper to describe and cryptanalyze the KeeLoq block cipher. Key words: KeeLoq block cipher, cryptanalysis, slide attacks, guess- and-determine attacks, distinguishing attacks 1 Introduction A large proportion of modern block ciphers are built upon Feistel networks. Such cryptographic algorithms as DES [22], Blowfish [26], KASUMI [6], GOST [32] or RC5 [25] are based on balanced Feistel networks. Other block ciphers use source-heavy or target-heavy unbalanced Feistel networks (e.g. REDOC III [27], Skipjack [23], etc.). The most extreme case of a source-heavy unbalanced Feistel network [28] is a nonlinear feedback shift register (NLFSR), which can be applied in both stream cipher and block cipher designs. A number of NLFSR-based stream ciphers have been recently proposed (e.g. Achterbahn [8] and [7], Grain [9]) and successfully cryptanalyzed using linear [2] and nonlinear [11], [24] approximations of nonlinear feedback functions.
    [Show full text]
  • KEELOQ® with XTEA Microcontroller-Based Code Hopping Encoder
    AN1266 KEELOQ® with XTEA Microcontroller-Based Code Hopping Encoder Operation: Authors: Enrique Aleman Michael Stuckey • 2.0-5.5V operation Microchip Technology Inc. • Four button inputs • 15 functions available INTRODUCTION • Four selectable baud rates • Selectable minimum code word completion This application note describes the design of a • Battery low signal transmitted to receiver microcontroller-based KEELOQ® Hopping Encoder using the XTEA encryption algorithm. This encoder is • Nonvolatile synchronization data implemented on the Microchip PIC16F636 • PWM, VPWM, PPM, and Manchester modulation microcontroller. A description of the encoding process, • Button queue information transmitted the encoding hardware and description of the software • Dual Encoder functionality modules are included within this application note. The software was designed to emulate an HCS365 dual encoder. As it is, this design can be used to implement DUAL ENCODER OPERATION a secure system transmitter that will have the flexibility This firmware contains two transmitter configurations to be designed into various types of KEELOQ receiver/ with separate serial numbers, encoder keys, decoders. discrimination values, counters and seed values. This means that the transmitter can be used as two BACKGROUND independent systems. The SHIFT(S3) input pin is used to select between encoder configurations. A low on this XTEA stands for Tiny Encryption Algorithm Version 2. pin will select Encoder 1, and a high will select Encoder 2. This encryption algorithm is an improvement over the original TEA algorithm. It was developed by David Wheeler and Roger Needham of the Cambridge FUNCTIONAL INPUTS AND OUTPUTS Computer Laboratory. XTEA is practical both for its The software implementation makes use of the security and the small size of its algorithm.
    [Show full text]
  • (12) United States Patent (10) Patent N0.: US 7,492,898 B2 Farris Et Al
    US007492898B2 (12) United States Patent (10) Patent N0.: US 7,492,898 B2 Farris et al. (45) Date of Patent: Feb. 17, 2009 (54) ROLLING CODE SECURITY SYSTEM (56) References Cited U.S. PATENT DOCUMENTS (75) Inventors: Bradford L. Farris, Chicago, IL (US); 2,405,500 A 8/1946 Guannella James J. Fitzgibbon, StreamWood, IL 3,716,865 A 2/1973 Willmott (Us) 3,735,106 A 5/1973 HollaWay 3,792,446 A 2/1974 McFiggins et a1. (73) Assignee: The Chamberlain Group, Inc., 3,798,359 A 3/1974 Feistel 3,798,360 A 3/1974 Feistel Elmhurst, IL (US) 3,798,605 A 3/1974 Feistel Notice: Subject to any disclaimer, the term of this 3,845,277 A 10/1974 Voss et a1. patent is extended or adjusted under 35 U.S.C. 154(b) by 901 days. (Continued) (21) Appl. No.: 10/884,051 FOREIGN PATENT DOCUMENTS DE 32 34 538 Al 3/1984 (22) Filed: Jul. 2, 2004 (65) Prior Publication Data (Continued) US 2004/0243813 A1 Dec. 2, 2004 OTHER PUBLICATIONS Related US. Application Data NM95HSO l/NM95HS02 HiSeCTM. (High Security Code) Genera tor, National Semiconductor, Jan. 1995, l-l9. (60) Continuation of application No. 10/215,900, ?led on Aug. 9, 2002, noW Pat. No. 6,810,123, Which is a (Continued) continuation of application No. 09/981,433, ?led on Primary ExamineriHosuk Song Oct. 17, 2001, noW Pat. No. 6,980,655, Which is a (74) Attorney, Agent, or FirmiFitch, Even, Tabin & continuation of application No. 09/489,073, ?led on Flannery Jan.
    [Show full text]
  • Keeloq and Side-Channel Analysis — Evolution of an Attack
    KeeLoq and Side-Channel Analysis — Evolution of an Attack Christof Paar, Thomas Eisenbarth, Markus Kasper, Timo Kasper and Amir Moradi Chair for Embedded Security Electrical Engineering and Information Sciences Dept. Ruhr-Universitat¨ Bochum www.crypto.rub.de Abstract—Last year we were able to break KeeLoq, which State Register, y is a 64 bit block cipher that is popular for remote keyless 7 240 110 entry (RKE) systems. KeeLoq RKEs are widely used for access control purposes such as garage openers or car door systems. Even though the attack seems almost straightforward in hindsight, there where many practical and theoretical problems to overcome. In this talk I want to describe the evolution of the attack over about two years. Also, some possible future improvements using fault-injection will be mentioned. XOR During the first phase of breaking KeeLoq, a surprisingly long time was spent on analyzing the target hardware, taking Key Register, k measurements and wondering why we did not succeed. In the second phase, we were able to use differential power analy- 7 0 sis attacks successfully on numerous commercially available products employing KeeLoq code hopping. Our techniques allow for efficiently revealing both the secret key of a remote Figure 1. Block diagram of the KEELOQ encryption transmitter and the manufacturer key stored in a receiver. As a result, a remote control can be cloned from only ten power traces, allowing for a practical key recovery in a few minutes. With similar techniques but with considerably more measurements (typically on the order of 10,000) we can extract In addition to KEELOQ IFF systems which provide au- the manufacturer key which is stored in every receiver device, thentication of a transmitter to the main system using a e.g., a garage door opener unit.
    [Show full text]
  • Cryptanalysis of Keeloq with COPACOBANA
    Cryptanalysis of KeeLoq with COPACOBANA Martin Novotn´y1 and Timo Kasper2 1 Faculty of Information Technology Czech Technical University in Prague Kolejn´ı550/2 160 00 Praha 6, Czech Republic email: novotnym@fit.cvut.cz 2 Embedded Security Group Ruhr-University Bochum Universit¨atsstrasse150, 44801 Bochum, Germany email: [email protected] Abstract. Many real-world car door systems and garage openers are based on the KeeLoq cipher. Recently, the block cipher has been exten- sively studied. Several attacks have been published, including a complete break of a KeeLoq access control system. It is possible to instantly over- ride the security of all KeeLoq code-hopping schemes in which the secret key of a remote-control is derived from its serial number. The latter can be intercepted from the communication between a receiver and a trans- mitter. In contrast, if a random SEED is used for the key derivation, the cryptanalysis demands for higher computation power and may become infeasible with a standard PC. In this paper we develop a hardware architecture for the cryptanalysis of KeeLoq. Our brute-force attack, implemented on the Cost-Optimized Parallel Code-Breaker COPACOBANA, is able to reveal the secret key of a remote control in less than 0.5 seconds if a 32-bit seed is used and in less than 6 hours in case of a 48-bit seed. To obtain reasonable cryptographic strength against this type of attack, a 60-bit seed has to be used, for which COPACOBANA needs in the worst case about 1011 days for the key recovery.
    [Show full text]
  • A Complete Break of the Keeloq Code Hopping Scheme
    On the Power of Power Analysis in the Real World: A Complete Break of the KeeLoq Code Hopping Scheme Thomas Eisenbarth1,TimoKasper1, Amir Moradi2,, Christof Paar1, Mahmoud Salmasizadeh2, and Mohammad T. Manzuri Shalmani2 1 Horst G¨ortz Institute for IT Security Ruhr University Bochum, Germany 2 Department of Computer Engineering and Electronic Research Center Sharif University of Technology, Tehran, Iran {eisenbarth,tkasper,moradi,cpaar}@crypto.rub.de, {salmasi,manzuri}@sharif.edu Abstract. KeeLoq remote keyless entry systems are widely used for access control purposes such as garage openers or car door systems. We present the first successful differential power analysis attacks on nume- rous commercially available products employing KeeLoq code hopping. Our new techniques combine side-channel cryptanalysis with specific properties of the KeeLoq algorithm. They allow for efficiently revealing both the secret key of a remote transmitter and the manufacturer key stored in a receiver. As a result, a remote control can be cloned from only ten power traces, allowing for a practical key recovery in few minutes. After extracting the manufacturer key once, with similar techniques, we demonstrate how to recover the secret key of a remote control and repli- cate it from a distance, just by eavesdropping on at most two messages. This key-cloning without physical access to the device has serious real- world security implications, as the technically challenging part can be outsourced to specialists. Finally, we mount a denial of service attack on a KeeLoq access control system. All proposed attacks have been verified on several commercial KeeLoq products. 1 Motivation The KeeLoq block cipher is widely used for security relevant applications, e.g., remote keyless entry (RKE) systems for car or building access, and passive radio frequency identification (RFID) transponders for car immobilizers [13].
    [Show full text]