CN1134206A - 远端无按键进入系统中的发射机/接收机对的自动再同步方法 - Google Patents

远端无按键进入系统中的发射机/接收机对的自动再同步方法 Download PDF

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CN1134206A
CN1134206A CN94194018A CN94194018A CN1134206A CN 1134206 A CN1134206 A CN 1134206A CN 94194018 A CN94194018 A CN 94194018A CN 94194018 A CN94194018 A CN 94194018A CN 1134206 A CN1134206 A CN 1134206A
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transmitter
receiver
synchronization program
program again
random number
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D·S·拉特卡
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Lear Corp EEDS and Interiors
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    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07CTIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00Individual registration on entry or exit
    • G07C9/00174Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C9/00182Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with unidirectional data transmission between data carrier and locks
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/12Transmitting and receiving encryption devices synchronised or initially set up in a particular manner
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/32Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
    • H04L9/3226Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials using a predetermined code, e.g. password, passphrase or PIN
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/32Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
    • H04L9/3236Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials using cryptographic hash functions
    • H04L9/3242Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials using cryptographic hash functions involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC
    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07CTIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00Individual registration on entry or exit
    • G07C9/00174Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C9/00182Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with unidirectional data transmission between data carrier and locks
    • G07C2009/00238Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with unidirectional data transmission between data carrier and locks the transmittted data signal containing a code which is changed
    • G07C2009/00253Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with unidirectional data transmission between data carrier and locks the transmittted data signal containing a code which is changed dynamically, e.g. variable code - rolling code
    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07CTIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00Individual registration on entry or exit
    • G07C9/00174Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C2009/00753Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys
    • G07C2009/00769Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means
    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07CTIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C2209/00Indexing scheme relating to groups G07C9/00 - G07C9/38
    • G07C2209/06Involving synchronization or resynchronization between transmitter and receiver; reordering of codes

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  • Computer Security & Cryptography (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Lock And Its Accessories (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Detection And Prevention Of Errors In Transmission (AREA)

Abstract

藉助于在通信程序的起始时产生文电鉴定码的检验和并把它与以前存储的检验和相比较的方法在通信程序期间检测被破坏的存储器。如果检验和不一致,就开始自动再同步程序,其中由发射机产生随机数,广播给接收机为以后用作为滚动码或线性反馈移位寄存器变量。

Description

远端无按键进入系统中的 发射机/接收机对的自动再同步方法
本发明的领域
本发明总的是涉及无按键进入系统(Keyless entry system)。更具体地,本发明涉及用于当同步由于,例如,瞬时电源掉电或电池电压低而丢失时自动再同步发射机/接收机对的方法。
滚动码文电鉴别(roling code authentication)是移动物进入安全的通用形式。在这样的系统中,发射机以按键表(key fob)的形式来提供,而接收机位于移动物中,它能在移动物中接收按键表发射机(key fob transmitter)的编码发射信号。滚动码文电鉴别可籍助于使用和每个按键表命令一起进行工作的简单的线性计数器来实施。移动物中的接收机被做成总是期待一个增加值,因此它不允许重复计数器值。这样,为了达到同步发射机计数器应当决不落后于接收机的计数,也不应当比接收机的计数领先太多。使用线性反馈移位寄存器技术的更复杂的文电鉴别也被用作为移动物进入安全的更安全的技术。
根据多种理由,当发射机计数器值小于接收机计数器值时或当发射机计数器值比接收机计数器值大过一个预定数时,滚动码文电鉴别系统可随时失去同步。失去同步的原因是破坏了非永久性存储器,这是由于电池电源的瞬时掉电或电池电压过低所造成的。
确保同步不丢失的一个方法是以诸如EEPROM的永久性存储器装备发射机,这些存储器可存储滚动值因而它们将不会丢失。由于EEPROM是永久性的,它将不会因电源中断(例如,断开电池的连接或电池失效)而丢失同步。当内部的RAM(随机存取器)断电时,EEPROM保护计数器的完整性。
然而,EEPROM相当昂贵,所以希望在滚动码文电鉴别电路中去掉它们。这就提出一个问题,即由于没有永久性存储器,系统必须依赖于RAM(非永久性存储器)来存储计数器值。对依赖RAM的需要增大了破坏计数器值的可能性,因为即使由电池连接松开或电池充电不足而造成的暂时的电源掉电也会破坏同步。
本发明藉提供在检测到有破坏的存储器时能自动再同步发射机/接收机对的系统来提出同步可题。通常,用户甚至不知道进行过再同步。这是藉计算和存储表示在最初时的发射机状态的第一检验和来完成的。以后,通信序列在发射机和接收机之间开始,且该序列的起始自动导致第二检验和的计算。第二检验和表示在第二阶段时发射机的状态。对检验和加以比较,如果检验和不同,再同步序列就自动起始。
为了更完整地了解本发明,及其目的和优点,可以参阅以下的阐述和附图。
附图的简要说明
图1是示例性四比特线性反馈移位寄存器的方框图,它对了解本发明的原理是很有用的;
图2是说明本发明原理的总的流程图;
图3-6是详细阐述本发明的同步方法的流程图。
较佳实施例的描述
为了了解同步方法,对线性反馈移位寄存器技术的适当了解是有帮助的,因为本发明可和线性反馈移位寄存器(LFSR)安全系统一起使用。因此,在图1的10表示了一个四比特线性反馈移位寄存器(LFSR)。移位寄存器包括四个存储单元其中可存储四个比特,依次被表示为比特3,比特2,…比特0。移位寄存器被配置成使得每次循环或旋转导致一个比特的内容被移位或被转移到其右边的比特(除了那些被送到异或器件的比特以外)。
LFSR器件也包括一次或多次异或运算。在图1中,显示了一个单个的异或门12,其输出端提供给比特0,其输入端连接到比特1的输出端和比特0的输出端,如图所示。这样,每次循环或旋转后,比特1的内容和比特0的内容以异或运算相结合,然后把结果存储在比特0。图1所显示的线性反馈移位寄存器10仅仅作为例子被提供。实际上,移位寄存器可以是任意个比特数,典型地是比四大的比特数,并且异或运算的个数和位置可以改变以给出不同的加密编码。
在无接健进入系统中,线性反馈移位寄存器通过在带有位于几个比特位之间的异或反馈抽头的移位寄存器中将文电鉴别比特旋转n次来进行工作。在每次发送时,发射机完成线性反馈移位寄存器(LFSR)移位运算,它扰乱文电鉴别信息并把该扰乱的文电鉴别信息和所选定的命令(打开,锁上,中继(trunk),等等)一起送到接收机。在接收机接收到来自发射机的命令后,在接收机中进行对接收机文电鉴别变量的同样的LFSR运算。接收机将其自己的LFSR运算结果与发送机发送的文电鉴别变量进行比较。如果接收机的比较结果是一致的,那么文电鉴别信息被确认。
当发射机文电鉴别变量由于电源中断而丢失时,就会引起同步问题。本发明给出用于自动检测被破坏的文电鉴别变量和对这些变量再同步的方法。
现参考图2,将给出同步方法的总貌。然后将利用图3-6给出详尽的解释。现参考图2,当发射程序通过用户按压按键被起动时,同步方法就被自动调用。这在步骤20中被阐述。为响应于步骤20,在步骤22计算检验和,该检验和就与在以前的发送程序期间所计算的并被存储的检验和相比较。如果检验和是一致的,就发送用户所选定的命令,如同在步骤30中所表示的那样。另一方面,如果检验和不一致,就在步骤26发送再同步命令和一系列再同步变量。然后,在步骤28计算新的检验和,以后例程从分支返回,重复步骤22和24。
由图2可以看到,如果检验和不一致,例如,由于电源暂时掉电和由此造成的所存储的检验和的丢失,那么再同步程序将确保在下一个周期时检验和的一致。另外,借助于步骤26,接收机被提供以再同步变量,以允许它也和新的文电鉴别码相匹配。
现参考图3,从按下按键表的(状态100)这一点开始,来阐述同步方法。从此状态出发,控制进到步骤102,在此步骤,把以前存储的检验和与新计算出的检验和进行比较。如果检验和一致,就表明存储器未遭破坏。另一方面,如果检验和不一致,就表明存储器被破坏了。这样,在步骤104,如果存储器未被破坏,控制进到步骤106。步骤106最后将引导到步骤122,在此步骤执行用户所选定的命令。另一方面,如果存储器被破坏,控制进到步骤126,藉此,同步被再建立。下面将解释这两种可能的情况。如果存储器未被破坏
当存储器在步骤104中被确定时是未被破坏的,用户的按键板输入由发射机微处理器去解束和译码。这在步骤106被说明。然后,发射机滚动码或密码算法按顺序进行,如步骤108所示。关于程序化运行的另外的细节将结合图4和5进行阐述。
一旦滚动码已按顺序进行,发射机在步骤110组合信息,且该信息在步骤112通过RF或IF被广播发送到位于移动物中的接收机。然后,接收机在步骤114接收所发送的信息,藉此,接收机在步骤116完成其滚动码或密码算法的程序化。在此时,分别在步骤108和116产生的文电鉴别码在步骤118进行比较。如果文电鉴别码一致,且如果所发送的命令正确地译码,那么发射机在步骤120被看作为是正当的并且处理命令在步骤122被执行。
在另一种情况下,如果文电鉴别码不一致或如果所发送的命令未被有意义地译码,那么步骤120将使处理过程进入支路到步骤124,在此步骤程序被认为失去同步或另外可以认为是非法的按键表发射机。换句话说,在步骤124,或者是使用了不正确的发射机(在这种情况下,命令将决不会成功),或者虽然使用正确的发射机但它在顺序上和接收机不一致。如果存储器被破坏--重新同步过程
如果在步骤104存储器被判断破坏了,控制进到步骤126,在此步骤,开始再同步过程。在步骤126,发射机启动计数器以及用随机数装载到其LFSR变量中。然后发射机在步骤128组合信息,且该信息在步骤130通过RF或IF传输被发送到接收机。接着,在步骤132,计算出发射机RAM的检验和并将其存储。然后在步骤134,进行比较以确定存储在接收机中的最后五个随机数中的任一个是否和发射机广播的那些数相匹配。(尽管本较佳实施例测试了五个数,但是如果想要,可使用更大的或更小的数组)。如果这些数一致,步骤134被宣布为失效,由发射机发送的LFSR变量被接收机拒绝。在这种情况下,接收机和发射机将不同步。另一方面,如果最后五个再同步数中的任一个不一致,就表明成功地进行了再同步。在步骤136作出这一宣布后,接收机获得发射机发出的再同步变量,并把它们放在自己的滚动码LFSR变量寄存器中,藉此,发射机和接收机现在都包括同样的LFSR和计数器变量,因而处在同步状态。进一步实现的详述
被发射机和接收机所利用的LFSR程序如图4所示。从步骤140开始,程序进行步骤142,在此步骤,序列中的字节数被给定并开始软件循环以实现LFSR循环。如前面所解释的那样,一个或多个异或运算可被插入在给定字节或字的所选定的比特之间。(在图1中单个异或运算位于比特1和比特0之间)。在步骤142,一个或多个异或运算的选定位置被设定,因而在循环进行时,将发生合适的异或运算。如果想要,异或运算的选定配置可以作为设定参数以数字字或“掩码”的形式给出。替换地,掩码可被制造者或经销商永久地或半永久地制做在系统中或被编程在系统中。
接着,在步骤144,把一个字节放进LFSR的RAM变量中,因而可藉此执行LFSR程序。这在步骤146,148,和150中被阐述。在步骤146中对LFSR变量执行向右循环操作,最高比特(MSB)在进位寄存器中被强迫置零。异或运算在步骤148中被执行,其结果按照在步骤142所建立的设定的掩码作为反馈项被给出。然后,在步骤150,由步骤146和148给出的循环后的字节被存储在暂存器单元中。接着,在步骤152,如果还有附加的字节排列着要循环,那么程序返回步骤144,在此步骤提取下一个字节并重复此处理过程。
一旦所有的字节都按照步骤144-150被循环后,暂存器(在步骤150所存储的)被写入RAM中的LFSR变量,且控制返回(步骤156)到调用程序。
图5显示了从步骤158开始的序列化滚动码的方式。如步骤160所显示的,滚动计数器变量从RAM中检索,然后把该变量增加1(步骤162)并且再存回到RAM中(步骤164)。然后控制返回到调用程序(步骤166)。
本较佳实施例对发射机信息的组合如图6所示。从步骤168开始,藉首先把发射机ID(识别符)放置在第一传输字节中(步骤170)组合发射机信息。接着,对信息是再同步信息还是常规命令做出决定(步骤172)。藉助于把滚动比特和LFSR数据放置在要发送的后续的39个比特中来组合常规命令(步骤174)。如果命令是再同步命令,那么藉首先产生或提取作为LFSR/滚动数起始变量的随机数(步骤176)来组合信息。接着,在步骤178,异或再同步命令被插入到信息中。以后(步骤180)再同步比特被放在信息中并和想要的命令一起被放置到后续39个传输比特中。
一旦信息被组合(或者是常规的或者是再同步的),就为该信息计算纠错码或检验和,它也被放置在信息中放在最后的传输比特位置。这样,就组合好了要从发射机发送到接收机的信息。因而接收机能按相反的程序过程对信息进行译码。在信息被组合好以后,程序返回(步骤184)到其调用程序。
虽然已说明了使用线性反馈移位寄存器技术的滚动码文电鉴别,但同步发射机和接收机的方法并不限于LFSR技术。总的来说,本发明可和任何能支持检验和的密码文电鉴别一起使用。
虽然本发明是以本优先实施例来加以描述的,但可以看到,本发明能加以修改而不背离如在所附权利要求中所述的本发明的精神。

Claims (6)

1.无按键进入系统中同步发射机和接收机的方法,包括:
计算和存储表示在第一次时的发射机状态的第一错误检验码;
起始发射机和接收机之间的通信程序;
响应于起始通信程序,自动计算表示在第二次时的发射机状态的第二错误检验码;
比较第一和第二错误检验码,如果所述码不同,自动起始所述发射机和接收机之间的再同步程序。
2.根据权利要求1的方法,其中所述再同步程序包括使用所述发射机发送再同步信息给所述接收机。
3.根据权利要求2的方法,其中所述再同步程序包括产生至少一个随机数并把它从发射机发送到接收机。
4.根据权利要求2的方法,其中所述再同步程序包括在所述接收机中存储一个命令译码值,并把第一命令值从发射机发送到接收机且只在所述第一命令值与所存储的命令译码值相一致时,完成所述同步程序。
5.根据权利要求1的方法,其中所述再同步程序包括以下步骤:
在所述发射机中产生和存储至少一个第一随机数;
在所述接收机中产生和存储至少一个第二随机数;
发送至少一个所述第二随机数给所述接收机;
比较第一和第二随机数并根据该比较的结果:
(a)如果所述第一和第二随机数相一致,表明发射机和接收机处在同步状态;
(b)如果所述第一和第二随机数不一致,表明发射机和接收机不同步。
6.根据权利要求1的方法进一步包括响应于再同步程序的启动,计算和存储新的检验和,以代替所述第一检验和。
CN94194018A 1993-11-05 1994-11-07 远端无按键进入系统中的发射机/接收机对的自动再同步方法 Pending CN1134206A (zh)

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