CN1225096C - High safety remote controller coding device - Google Patents
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- CN1225096C CN1225096C CN 02131636 CN02131636A CN1225096C CN 1225096 C CN1225096 C CN 1225096C CN 02131636 CN02131636 CN 02131636 CN 02131636 A CN02131636 A CN 02131636A CN 1225096 C CN1225096 C CN 1225096C
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Abstract
The present invention discloses a high safety remote controller coding device which comprises a timer, a mode selector, a controller which is used for receiving a certification serial number and transmitting a timing value and a mode selection value so as to generate a control signal, a cryptographic key, an encipherer which is used for receiving the control signal and encrypting the control signal into a cipher text by using the cryptographic key, an RF modulator which is used for modulating the cipher text and outputting the cipher text. The present invention also discloses a method for improving the power consumption of a remote controller, which comprises the following steps: activating a coding device; activating the timer of the coding device; encrypting the transmission timing value and the certification serial number of the timer and transferring the transmission timing value and the certification serial number to a translating device; comparing received data and the timing value of the translating device by the translating device; synchronizing the timer of the translating device and the timer of the coding device; judging whether to activate the coding device for a second time within a period of time, if false, then, timing is stopped, but a final timing value is still stored in a memory; if true, then the steps of the method of the present invention are repeated until a controlled device is activated.
Description
Technical field
The present invention relates to a kind of remote controller coding device, it particularly is a kind of remote controller coding device of high security, the counter that wherein replaces conventional art with timer, making ' stopping-heavily send ' attack is difficult to succeed, improving the fail safe of remote control system, and improve the power consumption problem of remote controller.
Background technology
Remote controller has become one of people's daily living article, even automobile, gate, tame family seehears etc. such as all need to use with convenient by wireless remote control.Though some remotely-controlled objects need not prevent security mechanisms such as other people misapply, steal, also having a lot of application to need with safety is overriding concern.Should prevent that as automobile remote-control device etc. the burglar from invading the stealing automobile, even seehears also need there be some safe designs, watch program of unsuitable for children etc. to avoid child.
Generally speaking, remote control system can be divided into modes such as one-way operation and bidirectional operation.In one way operation system, controlling signal is entirely by the transmitting terminal emission, with the equipment of remote control receiving terminal; And the controlling signal of bidirectional operation system is via transmitting terminal and receiving terminal interworking, to determine the purpose of control.Though the bidirectional operation system can reach both sides' property confirmed (mutual authentication), and can obtain preferable control effect, complicated and expensive because of equipment, use so except that some important events, very lack.
The simplest remote control system is that controlling signal directly is sent to receiver with plaintext (plaintext) with wireless mode.If each plaintext that transmits is all identical, after then the assailant utilized scanner to intercept and capture (eavesdrop) signal, as long as heavily send (replay) to get final product success attack signal, so system was absolutely unsafe.Even the signal that system transmits comprises on-fixed numerical value such as random number and time, learn system architecture and function mode (can obtain easily usually) as if the assailant, can forge an effective signal, also attacking system successfully.
The mode of safety is controlling signal suitably to be encrypted (encrypt) back to begin to give to send, and receiving terminal is carried out after receiving signal deciphering (decrypt) again.This mode is if adopt the encryption equipment of safety, and the assailant can't learn the correct content of controlling signal.Yet if this system is as above-mentioned, each data that transmits is all identical, and after the assailant intercepted and captured signal, signal is also heavily sent must success attack but need only, and promptly system still is absolutely unsafe.But if the signal on-fixed that system transmits, but produce by some random numbers (random number) or sign indicating number book (codebook), as long as the entropy (entropy) of random number or sign indicating number book is enough big, even the assailant knows system architecture and function mode, for want of correct key, can't forge effective data, so attacking system successfully.But because following factors may be deceived traditional remote controller safety:
One, the random number number of traditional remote controller or sign indicating number book size;
Two, traditional remote controller system architecture and function mode are dangerous.
Above-mentioned factor causes the assailant can guess out the signal content easily, or via the whole controlling signal under the record, sends with activation receiver in regular turn again.So traditional remote control system, no matter whether controlling signal encrypts, all vulnerable.
Desire to make remote control system to reach safe demand, must use the modern cryptographic technique beginning to reach.Encrypting and deciphering system is divided into two kinds of symmetric key encrypting and deciphering system (symmetric key crypto-system) and asymmetric golden key encrypting and deciphering systems (asymmetric key crypto-system) etc.Division is as follows:
One, symmetric key encrypting and deciphering system: the symmetric key encrypting and deciphering system claims traditional encrypting and deciphering system again, shown in Figure 1A.In Figure 1A, the encryption of the transmitting terminal of system gold key 1 is identical with the deciphering gold key 2 of receiving terminal.When operation, encryption equipment 3 at first is encrypted to ciphertext C (ciphertext) with golden key 1 with plaintext M.Receiving terminal is after receiving this ciphertext C, and decipher 4 becomes plaintext M with key 2 deciphering that are same as golden key 1.According to the data encryption standard of American National Standard (data encryption standard, DES), the plaintext M of input is to be that unit is cut into a plurality of blocks with 64, each block is become 64 ciphertext C with 64 secret key encryption; Receiving terminal becomes 64 plaintext M with identical key K deciphering again.Since expressly identical with ciphertext length, comparatively economical in the transmission.
Two, asymmetric golden key encrypting and deciphering system: asymmetric golden key encrypting and deciphering system is called public key (Publickey) encrypting and deciphering system again, shown in Figure 1B.In Figure 1B, the encryption of the transmitting terminal of system gold key 1 ' is also inequality with the deciphering gold key 2 ' of receiving terminal.With famous Rivest-Shamir-Adelman (RSA) encryption system is example, and the input plaintext M is encrypted with the public key 1 ' of receiving terminal becomes ciphertext C, i.e. C=Me (mod N).Replying with one's own side's secret key (Private key) 2 ' deciphering after receiving terminal is received is plaintext M again, i.e. M=C
d(mod N).Wherein N is the open value of system, be to be the mutually product of two big prime number p with q, and ed=1mod ( (N)).For for the purpose of reaching safety, the common numerical value of N all quite big (at least 1024 bit length), and because of adopting exponent arithmetic, make computing time quite tediously long is therefore difficultly realized with modes such as single-chips in the asymmetric golden key encryption system; And cooperate the computer of tool high-speed computation to finish with software mode usually.But, indispensable on network and e-business etc. are used because of asymmetric golden key encryption system has the function of authentication.
At the remote control system of the most normal use at present, as U.S. Pat 5,517,187 disclosed remote control systems, wherein the schematic diagram of the reflector of this system and receiver is respectively shown in Fig. 2 A and Fig. 2 B.In Fig. 2 A, reflector 10 comprises: a counter 11, and so that an emission count value C to be provided
TOne mode selector 12 is to provide a model selection value Mo; One controller 13 receives this emission count value and this model selection value, and to produce a controlling signal, it is to represent with plaintext M; One key 14; One encryption equipment 15 is to receive this controlling signal, and with this key 14 this controlling signal is encrypted to ciphertext C; And a radio-frequency modulator 16, be with this ciphertext modulation and with it output.And in Fig. 2 B, receiver 20 comprises: a radio-frequency (RF) demodulator 16 ', and will be with the signal that reflector is exported with demodulation; One key 14; One decipher 15 ' is to receive this demodulation signal, and with this key 14 this demodulation signal is decrypted into plaintext M; One counter 11 is to produce a count pick up value C
ROne controller 13 receives this plaintext and this count pick up value; And a detector 17, check whether whether the value of counter correctly continue to carry out with decision.
Wherein, the controlling signal M of reflector comprises this model selection value Mo and this emission count value C
T, that is:
M＝{Mo，C
T}
Wherein Mo is the value of model selection buffer, and length is 32bits, and its content is model selection key information, company's production code member, other is relevant with the reservation position of preparation etc.Model selection can be divided into normal or synchronous mode, and its transmission data is similar to the receiving check step, and only the data bits of Jian Chaing is different with scope.C
TFor depositing the value of counter, because of the counter total length is 32bits, so its password amounts to 2
32Individual.For general remote controller, its degree of safety should be enough.
The common key K of emission and the equal tool of receiving terminal one in the system, and one 32 counter is respectively arranged.After system comes into operation or reforms, receiving terminal counter C
RContent be transmitting terminal counter C
TAdd 1.Counter C before the each emission of the counter of transmitting terminal
TValue promptly add one.Transmitting terminal is sent to receiving terminal after above-mentioned data M is encrypted in the mode of symmetric key with K.
Combine speech, U.S. Pat 5,517, the method for operation of 187 disclosed remote control systems, it is characterized in that this receiving terminal is received the output signal of transmitting terminal after, inspection:
One, decision is to be normal or synchronous mode;
Two, the emission count value C that receives of decision
TValue C with the receiving terminal counter
RWhether conform to, i.e. n 〉=C
T-C
R〉=0; Wherein, n for security-related be several.For example get n=5, promptly allow maximum five abortive launch of system transmitter;
Three, above-mentioned steps two then makes counter synchronisation (even C if meet
R=C
T+ 1), and activator switch; Be not failure to actuate if be inconsistent then.This moment, system promptly entered synchronous mode if transmitting terminal transmits the signal that requires synchronously, carry out back receiving terminal counter will with transmitting terminal synchronously and regular event.(its program is identical with normal step, and only the data that transmits changes another group password and count value into, is that number amplifies simultaneously with safety, as gets n=100 etc.); And
Four, if normal mode or synchronous mode all can't activation receivers, promptly should send burning again or maintenance back to.
Yet there is a great disappearance in this system, and promptly system if the assailant stops (mask) with this signal, makes receiving terminal 20 can't normally receive signal when transmitting signal, and this moment, receiving terminal was with attonity.General user can leave request support when receiver 20 can't operate as normal if use a teleswitch for several times usually.But this moment, assailant 5 was if heavily give receiving terminal 20 with the signal that receives, as long as the numerical value of counter is in reasonable range, receiver 20 promptly can normal operation, that is attack can be succeeded.When using synchronous mode, still as described above, attacking also can be successful.Because the opening of wireless remote control signal, and the assailant is easy to buy the scanner of any pattern, so the lawbreaker can intercept and capture and write down any signal easily, stops through receiving, signal intercepts and captures again that signal heavily send (being called for short " stopping-heavily send "), attack can be succeeded easily, as shown in Figure 3.
In addition, a kind of rolling code formula (rolling code) system and a kind of frequency hopping (hopping code) system are still arranged.In rolling code formula system, receiver is whenever received signal one time, signal correctness no matter, and counter can add a numerical value immediately, for example 1.Thereby in normal running each time, if the assailant heavily gives the recipient after intercepting and capturing signal again, then because of the Counter Value of receiver greater than the signal person, so can't normal operation.For example originally the count value of reflector is 100 and the receiver value is 101, this moment reflector if the emission signal, then its count value becomes 101; When receiver was received correct signal, because of the data of two count values conforms to, system was normal operation, and counter is added 1 and make its value become 102.If it is 101 transmission signal that this count value content is obtained in the record of certain assailant's side, heavily give this signal to give receiving terminal again, this moment, the counter because of receiving terminal was 102, so data does not conform to, the system that makes decommissions.But if the assailant constantly repeats to send this signal,,, cause system from then on can't operate, must send the manufacturer place back to and reset because the count value of receiving terminal exceeds safe range because of constantly adding up though system receiving terminal is unlikely normal output.
Be with, in rolling code formula system, if the assailant uses as above-mentioned method stops signal, because the counter of receiving terminal keeps initial value, this moment, the assailant was if the signal that will intercept and capture heavily send, receiver promptly can normal operation, makes to attack and succeeds.
In addition, the frequency hopping system also as mentioned above, only its counter is the output (that is, can reach via the pseudorandom number producer) of great-jump-forward, also is difficult to keep out the attack of " stopping-heavily send " formula.
Therefore,, except the attack that can successfully resist " stopping-heavily send " formula, can also improve the power consumption problem of remote controller, be invention emphasis of the present invention how at the shortcoming of above-mentioned traditional technology and propose a kind of high security remote controller coding device.
Summary of the invention
Main purpose of the present invention provides a kind of high security remote controller coding device, and it uses a timer, can successfully resist the attack of ' stopping-heavily send ' formula, to improve the fail safe of system.
In order to reach above-mentioned purpose of the present invention, a kind of high security remote controller coding device provided by the invention comprises: a timer, so that an emission clocking value to be provided; One mode selector is to provide a model selection value; One controller receives an authentication sequence number, this emission clocking value and this model selection value, to produce a controlling signal; One key; One encryption equipment receives this controlling signal, and with this key this controlling signal is encrypted to ciphertext; And a radio-frequency modulator, with this ciphertext modulation and with it output.
This timer length can need and difference be arranged according to design, generally is the timer that can select 8,16 or 32 for use.
The preferably, this key is to be one 64 keys, also can increase or shorten figure place according to need, for example 16,32,128 etc.
The preferably, this key be deposit in one non-volatile (non-volatile) but in the internal memory or use once program read-only memory (one time program ROM).
The length of this emission clocking value is decided according to the timer of selecting for use, as 32 bit timing devices then clocking value length be 4 bytes (byte), whether the time difference between the timer of its timer that is used for checking code device and corresponding code translator in a patient time.
The preferably, the length of this model selection value is 2 bytes, in order to select a kind of pattern according to actual needs from normal mode, emergency mode and synchronous mode.
The preferably, the length of this authentication sequence number is 2 bytes, uses for corresponding code translator checking.
The preferably, this controlling signal is to represent with plaintext M.
The preferably, this ciphertext is with symmetric key mode encipherer.
The preferably, this timer is to realize with the timing interrupt mode in the single-chip.
The preferably, this timer is realized with a logical circuit.
The present invention also provides a kind of method of improving the remote controller power consumption, comprising: the activated code device; The timer of activated code device; The emission clocking value of this timer is encrypted with the authentication sequence number, and it is sent to this code translator; Code translator is compared the data that is received with the clocking value of itself; The timer of code translator and the timer of code device are synchronous; Whether judgement has activated code device once more in a period of time; If not, then timing stops, but last clocking value still is stored in the internal memory, if, then repeat above step, be activated up to the device of being controlled.
By following with reference to accompanying drawing with the instantiation detailed description of the invention, can more clearly understand above-mentioned purpose, content and effect.
Description of drawings
Figure 1A is the block diagram of traditional symmetric key encryption system;
Figure 1B is the block diagram of traditional asymmetric golden key encryption system;
Fig. 2 A is a U.S. Pat 5,517, the block diagram of the reflector of 187 remote control system;
Fig. 2 B is a U.S. Pat 5,517, the block diagram of the receiver of 187 remote control system;
The block diagram of the attack pattern that Fig. 3 ' stops-heavily send ' for conventional remote control systems;
Fig. 4 A is the block diagram for the remote controller coding device of the specific embodiment of the invention;
Fig. 4 B is the block diagram for the remote controller code translator of the specific embodiment of the invention;
Fig. 5 is the block diagram for the timer of the specific embodiment of the invention;
Fig. 6 is the block diagram for the timer of another specific embodiment of the present invention; And
Fig. 7 is code translator patient time of the present invention (Tolerance time), safety time (Safe time), timing chip accuracy (Accuracy) and activationary time relation at interval.
The drawing reference numeral explanation: 1 encrypts golden key; The golden key of 2 deciphering; 3 encryption equipments; 4 deciphers; 1 ' encrypts golden key; 2 ' deciphers golden key; 3 ' encryption equipment; 4 ' decipher; 10 reflectors; 20 receivers; 11 counters; 12 mode selectors; 13 controllers; 14 keys; 15 encryption equipments; 16 radio-frequency modulators; 15 ' decipher; 16 ' radio-frequency (RF) demodulator; 17 detectors; 30 code devices; 40 code translators; 31 timers; 31 ' timer; 32 mode selectors; 33 controllers; 33 ' controller; 34 keys; 34 ' key; 35 encryption equipments; 36 radio-frequency modulators; 35 ' decipher; 36 ' radio-frequency (RF) demodulator; 37 buffers; 51 oscillators; 52 frequency dividers; The built-in counter of 53 single-chips; 54 system counters; 61 oscillators; 62 frequency dividers; 63 counters.
Embodiment
The invention discloses a kind of remote controller coding device of high security, it is characterized in that replacing the counter of conventional art with timer, make ' stopping-heavily send ' attack and be difficult to succeed, improving the fail safe of remote control system, and improve the power consumption problem of remote controller.Be elaborated with reference to the accompanying drawings, wherein identical reference number is represented identical assembly.
Fig. 4 A is the block diagram for the remote controller coding device of the specific embodiment of the invention.In Fig. 4 A, this code device 30 comprises: a timer 31, and so that an emission clocking value T to be provided
TOne mode selector 32 is to provide a model selection value Mo; One controller 33 receives an authentication sequence number N, emission clocking value and model selection value, to produce a controlling signal; One key 34; One encryption equipment 35 receives this controlling signal, and with this key 34 this controlling signal is encrypted to ciphertext C; And a radio-frequency modulator 16, with this ciphertext modulation and with it output.
Specifically, in code device of the present invention, this timer be for one 32 bit timing devices and this key be to be one 64 keys.This key is to deposit among non-volatile (non-volatile) internal memory such as ROM or the EPROM.
This controlling signal is to be expressed as with plaintext M: M={Mo, N, T
T.Wherein, Mo is model selection (modeselect) value, and N is authentication sequence number (identity), T
TBe the emission clocking value, be respectively described below:
One, Mo: model selection, length are 2 bytes, and it comprises model selection and other standby data, in order to select a kind of pattern according to actual needs from normal mode, emergency mode and synchronous mode.
1) normal mode: when being used in normal use.In this pattern, the patient time of corresponding code translator (tolerant time, T
L) less.When patient time guarantees system's energy normal operation, the worst error value of two timers of coding that code translator sets and code translator.Patient time is bigger than the Generally Recognized as safe time (safetime).Safety time then is the actual worst error value of coding with two timers of code translator.For example, if the accuracy of timer is ± 1010
-6The time, coding is 2010 with the actual worst error value of two timers of code translator
-6, be about 2sec/ days.The safety time that is equivalent to 30 days is 1 minute.If time of bearing of trying to please is the twice of safety time, then expression allows that the error amount between two timers of coding and code translator is 2 minutes.The system that so can guarantee can normal operation, and reason system timing error does not increase for some reason, and the puzzlement that can't activate.
2) emergency mode: timing error is above the patient time of normal mode for some reason if coding is with the code translator both sides, and then normal mode can't active device.Can utilize this moment emergency mode to solve.This mode operating such as normal mode, only the patient time of code translator is bigger.But this modular system degree of safety will reduce, and should note behind the active device and can not leave in patient time.
3) synchronous mode:, then enter synchronous mode if normal mode and emergency mode all can't make the code translator output action.This pattern is more loose in the scope of examination of code translator end, and for example only comparison authenticates sequence number or patient time etc.The method emergency mode as described above is general, and the system safety degree is lower, should more note attacking in patient time the problem of ' stopping-heavily send '.
Two, N: the authentication sequence number, length is 2 bytes, for corresponding code translator checking usefulness, and its content comprises product serial number or other parameter.
Three, T
T: the emission clocking value, length is 4 bytes (byte), whether the time difference between the timer of its timer that is used for checking code device and corresponding code translator is in a patient time.
In addition, this controlling signal is to represent with plaintext M.And this ciphertext is to encrypt in the symmetric key mode, and its length is 64.
For cooperating the remote controller coding device of the specific embodiment of the invention, its corresponding code translator 40 shown in Fig. 4 B, comprising: a radio-frequency (RF) demodulator 36 ', and will be with the signal that code device is exported with demodulation; One key 34 '; One decipher 35 ' receives this demodulation signal, and with this key 34 ' this demodulation signal is decrypted into plaintext M; One timer 31 ' receives clocking value T to produce one
ROne controller 33 ' receives this plaintext and this count pick up value; An and buffer 37.
The key 34,34 ' the content that note that code device 30 and code translator 40 are identical.Wherein, when deciphering running, controller 33 ' takes out Mo, N and T from M
T, carry out follow procedure again.
1) judges whether N is correct, then stop output if not.
2) if N is errorless, differentiating this signal is normal mode, emergency mode or synchronous mode.
3) compare T
TWith T
RIn patient time, promptly whether comparison | T
T-T
R|≤T
LIf then normal the activation exported, otherwise system promptly decommissions.Only when synchronous mode, receiving terminal is only checked the authentication sequence number, or still checks patient time as above-mentioned mode, but this patient time T
LSet point bigger, easier activation output equipment.(scope of examination of three kinds of pattern code translators can need design adjustment according to system).
4) no matter normal mode, emergency mode or synchronous mode, code translator promptly activates output equipment after confirming that input is errorless, and discipline T
TFor checking thereafter whether signal heavily send.
5) reset timing signal T
RMake itself and the timing signal T that receives
TSynchronously, even T
R=T
T, in order to avoid produce cumulative errors thereafter.
If when normal mode, emergency mode or synchronous mode all can't activate code translator, promptly the difference between presentation code device and the code translator both sides timer was very big, or plant failure, promptly should send back to reset or overhaul.
In the present invention, timer can be by the timing interrupt mode of single-chip for it, or a time set is set in addition reaches.Also even code device is consideration with cost factor, circuit complexity power consumption, and only finishes with logical circuit, and available one simple timing circuit is realized.Code translator all is provided with a single-chip, so can select the interrupt mode timing or put timing circuit in addition for it usually because of considering above-mentioned factor.Timer do not need as time set such as wrist-watch etc., need reach and reach millisecond with resolution synchronously with present time even the effect of microsecond, but only be a simple time set, its resolution reaches 0.5 second and gets final product.And for reaching secret effect, the initial value of timer can random number for it, that is initial value is non-vanishing, make the assailant very difficulty guess clocking value right.
For guaranteeing system safety and normal operation, timer reaches the synchronous requirement of two timer both sides that output is difficult for repetition and code device and code translator.
The single-chip HT48C50 that is researched and developed with Sheng group semiconductor is an example, if adopt the 400KHz oscillator, and 16 bit timing devices are set at the 0.5Sec interruption once, generation 2
32The time of inferior interruption is about 24855 days.Also even timing exports 4 buffers to, and then circulation primary needs 68 years approximately, so the timing signal polyisomenism can not take place.The timer square frame of realizing with single-chip timing interruption and timing logic circuit is respectively as Fig. 5 and shown in Figure 6.In Fig. 5, timer is to realize that with the timing interrupt mode in the single-chip this timer comprises: an oscillator 51, a frequency divider 52, the built-in counter 53 of a single-chip and a system counter 54.In Fig. 6, timer realizes that with logical circuit it comprises: an oscillator 61, a frequency divider 62 and a counter 63.
At the synchronization aspects of two timers of code device and code translator, with the stability of timer now approximately ± 1010
-6Calculate, about 69 days beginnings produced 1 minute error; The maximum difference that transmitting-receiving two sides produce is 2010
-6, that is be about 2sec/day.If setting patient time is 1 minute, then 34 days nonsynchronous situations of the unexpected generation receiving-transmitting sides of planted agent.Produce the predicament that code translator can't operate for avoiding receiving and dispatching two sides because of the error of timing, system should suitably adjust patient time T with software program
LPatient time T
LDesign can as shown in the formula:
T
L＝α·T
s+C
T
s＝T
d·Ac
α wherein: be a constant, this value can optionally be adjusted.For example when normal mode, can be set at 1～2, when emergency mode, can be decided to be 3～5, when synchronous mode, can be set at more than 5.
T
d: the interval time (time-between-operations) that is twice activation.
T
s: safety time is the worst error time of the timer of receiving and dispatching two sides.
C: time constant.Utilize normal receipts of this time with the energy normal operation of assurance system.Above-mentioned formula is not if there is this parameters C, then when twice continuous button, because of T
dVery little one-tenth T
L≈ 0.So when button for the second time,, may cause code translator to operate because of receiving and dispatching the time difference of two side's timing carries.The C value is got usually and was got final product in 0.5 second.
Ac: the additive value of the accuracy of receiving-transmitting sides timing.
For example if the time set accuracy of system's receiving-transmitting sides is ± 1010
-6, Ac=2010 then
-6, the timing difference of receiving-transmitting sides maximum is about 2sec/day.If this running is 10 days apart from the time of successfully operating last time, T then
s=T
dAc=10days2010
-6=17.28sec.If α=1.5 and C=0.5sec, then patient time T
L=α T
s+ C=1.517.28sec+0.5sec=26.42sec, promptly the bolter is if abortive launch needs only and began to leave after 26.5 seconds, and the assailant promptly can't utilize and stop-weigh that delivery method activates code translator.
Fig. 7 illustrates code translator patient time T
L(Tolerance time), safety time T
s(Safe time), timing chip accuracy Ac (Accuracy) and activationary time relation at interval.
If the assailant stops signal make receiving terminal can't receive signal, then receiving terminal is with attonity.If general user can try to figure out a period of time at the scene usually and leave can't active device the time.If through patient time T
LAfter, the assailant heavily gives receiving terminal with the signal that receives, because the receiving terminal clocking value has surpassed T
L, code translator is promptly refused regular event, therefore attacks and can not succeed.If the assailant still constantly attempts heavily sending, then need timing in the 24855 days beginning to get back to original value, so very difficult utilization of assailant heavily sent invasive system here.This kind ' stops-heavily send ' that attack can be divided into following two kinds of situations again:
1) system does not operate for a long time, i.e. T
d＞＞0, cause patient time to increase, the user need after the long time, begin to leave (as described above, if this operate apart from the time of successfully operating last time be 10 days, then should stop after 26.5 seconds the beginning can leave), to guarantee system safety.Otherwise if the assailant stops-heavily send attack, because of the bigger event of patient time, attack may be succeeded.
2) after system had just finished once successful running, and then the user carried out again, but the assailant stop at this moment-heavily send attack, cause legal user can't normally carry out running this time.This moment is because of the T of system
d≈ 0, even if this user leaves at once, the assailant also can't activate output, and attacking can be not successful.
Code translator has the array buffer to deposit used T
TSo, if the assailant intercepts and captures the signal of a normal operation when heavily sending at once, but the attack detecting person's of system repetition signal and give refusal.And when heavily sending after the assailant waits for a period of time, system is because of surpassing patient time again, also can check out the assailant and stops output.
Because it is identical with the time of code device that each timing of carrying out code translator is all reformed, and suitably adjust with the time interval of activating with the software control patient time, so no cumulative errors and unexpected stationary problem.
System adopts safe encryption equipment such as DES etc., and the assailant desires to guess right the key K of receiving-transmitting sides, takes 2
56μ s (the calculating function of establishing the assailant was carried out 1,000,000 times conjecture in 1 second) promptly needs 2285 approximately.And because of system does not send relevant plaintext, the assailant lacks plaintext and compares with ciphertext, and very difficulty is obtained correct key.
System's soft or hard is very simple, and its complexity did not increase multicircuit and computing as present commercially available prod.The remote control system that the present invention and U.S. Pat 5,517,187 are disclosed relatively be as shown in Table 1:
The comparison of the remote control system of table one, the present invention and U.S. Pat 5,517,187
| System item | The present invention | U.S. Pat 5,517,187 |
| Key technology | 32 of timers | 32 in counter |
| Key length | 64 | 64 |
| Can keep out " heavily sending " attacks | Be but need have more array 32bit buffer to deposit the T that used TValue | But be but as constantly heavily send then success attack |
| Can keep out " stopping-heavily send " attacks | Be but ought be for a long time usefulness not, need behind long patient time, begin and can leave | Can not |
Below, in the present invention, also disclose a kind of method of improving remote controller power consumption problem, use the useful life that prolongs battery.
The code device of remote control system of the present invention and code translator all are provided with timer, and the two has encryption equipment such as DES etc. and encryption and decryption gold key K.Timer is in case be continuous timing after activating, for the code translator of receiving terminal, usually can be connected on fixed power source equipment because of the place of installing, as automobile storage battery or domestic power supply, there be not considering of power saving, but the code device of transmitting terminal is because be that handheld device uses battery to be power supply generally, so have power saving or change considering of battery.Under situation is considered in power saving, still can use means of the present invention to be operated, the execution mode of two kinds of power savings is below proposed:
First kind of mode is: except the mode of aforementioned encryption and decryption, comparison for clocking value can change difference into relatively, i.e. Active Timer a period of time just when transmitting terminal is operated at every turn, though this clocking value may be different with the clocking value of receiving terminal, but adopt the factor of identical toggle rate during based on design, the toggle speed of two timers is identical, confirms so the code translator of receiving terminal can be compared the toggle speed of this clocking value whether transmitting terminal is the code device of pairing.In other words, after transmitting terminal began operation, timer came into operation, and does not forfeit out the clocking value of change, and receiving terminal judges promptly that the toggle rate of this evaluation is whether identical with receiving terminal and whether decision is the remote controller of pairing.
The second way is: when transmitting terminal a period of time does not use, its timer promptly stops timework, when the user presses the remote controller key of transmitting terminal once more, timer just continues timing, because the value of the timer of transmitting terminal and receiving terminal must be inequality in the case, so must make the signal that sends first is the signal of forced synchronism pattern, when receiving terminal receives this forced synchronism mode signal, can allow the timer of the timer of receiving terminal and transmitting terminal synchronous, so the signal that the transmitting terminal next one sends just can be judged according to aforementioned normal mode.Because only the signal of emission first after the transmitting terminal timer stops is the forced synchronism mode signal, its length only has the time about several milliseconds approximately, so the user does not generally have the sensation of delay, because then promptly can send normal signal after having launched the forced synchronism mode signal, perhaps require the user need be during without remote controller even by the twice emitting button in a period of time, receiving terminal just can move, and is to send the forced synchronism signal for the first time, is only normal signal for the second time.For fail safe is considered, prevent that the ambitious people from cutting record forced synchronism mode signal and follow-up normal signal on the side, clocking value in the time of can further making before the receiving terminal record forced synchronism pattern several times if be shown assailant's the signal that duplicates with the record identical table, does not promptly have the action of unlatching.
The above-mentioned method of improving the remote controller power consumption can be expressed as, and comprising: the activated code device; The timer of activated code device; The emission clocking value of this timer is encrypted with the authentication sequence number, and it is sent to this code translator; Code translator is compared the data that is received with the clocking value of itself; If under compulsory mode, the timer of code translator will be synchronous with the timer of code device; If under general modfel, code translator will judge whether the activated code device according to the clocking value that receives; For power saving is considered, the controller of code device will judge whether button is arranged in sometime, if no button promptly activates electricity saver and cuts off the power supply voluntarily; Which kind of pattern no matter, the last clocking value of reflector will be stored in its internal memory.Generally speaking, when code translator is received for the first time signal, because of time difference should really activate the device of being controlled very greatly.But after timer was synchronous, secondary signal should make system activate this device.
Because single-chip or other electronic installation in the general code device, its computing capability is limited, can't finish required mould multiplication of asymmetric system (modular multiplication) or module exponent (modularexponentiation) etc. fast than complex calculations, so should adopt the encryption and decryption device of symmetrical expression to realize.With still generally regarded as safe DES system at present is example, and single-chip utilizes the symmetrical expression method to carry out and once encrypts or decipher the required time, only needs several milliseconds approximately, answers non-time delay problem of a specified duration excessively in the use.Use vicennial DES of a specified duration though the new Encryption Standard AES of announcing is about to replace, the present invention also can change the encryption equipment of system into AES, and only longer because of the key of AES, the time of encryption and decryption will be long slightly.
In sum, the invention discloses a kind of remote controller coding device of high security, it is characterized in that replacing the counter of prior art, make ' stopping-heavily send ' attack and be difficult to succeed with timer, improving the fail safe of remote control system, and improve the power consumption problem of remote controller.
The above only is preferred embodiment of the present invention, can not be used for limiting the scope that the present invention implements, and all equalizations of doing according to claim of the present invention change and modify, and all should belong in the scope that the present invention contains.
Claims (13)
1. high security remote controller coding device comprises:
One timer, so that an emission clocking value to be provided, whether this emission clocking value is used in the timing time difference of the timer of checking code device on the code translator and the timer of code translator in a patient time, and promptly clocking value T is launched in judgement on code translator
TWith reception clocking value T
RThe absolute value of difference whether be less than or equal to patient time T
L
One mode selector is to provide the model selection value about patient time;
One controller receives authentication sequence number from authentication sequence number unit respectively, comes the emission clocking value of self-timer and model selection value from mode selector, to produce a controlling signal;
One key;
One encryption equipment receives this controlling signal, and with this key controlling signal is encrypted to ciphertext; And
One radio-frequency modulator is with this ciphertext modulation and with it output.
2. high security remote controller coding device as claimed in claim 1, wherein timer is one 32 bit timing devices.
3. high security remote controller coding device as claimed in claim 1, wherein key is one 64 keys.
4. high security remote controller coding device as claimed in claim 3, wherein key is deposited in the nonvolatile memory.
5. high security remote controller coding device as claimed in claim 1, the length of wherein launching clocking value are 4 bytes.
6. high security remote controller coding device as claimed in claim 1, the length of wherein model selection value are 2 bytes, in order to select a kind of pattern according to actual needs from normal mode, emergency mode and synchronous mode.
7. high security remote controller coding device as claimed in claim 1, the length that wherein authenticates sequence number are 2 bytes, use for corresponding code translator checking.
8. high security remote controller coding device as claimed in claim 1, wherein controlling signal is with expressly expression.
9. high security remote controller coding device as claimed in claim 1, wherein ciphertext is to encrypt in the symmetric key mode, and its length is 64.
10. high security remote controller coding device as claimed in claim 1, wherein the initial value of timer is a random number.
11. high security remote controller coding device as claimed in claim 10, wherein timer is realized with a logical circuit.
12. high security remote controller coding device as claimed in claim 10, wherein timer is to realize with the timing interrupt mode in the single-chip.
13. only just timing when remote controller coding device is operated of high security remote controller coding device as claimed in claim 1, wherein said timer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02131636 CN1225096C (en) | 2002-09-12 | 2002-09-12 | High safety remote controller coding device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02131636 CN1225096C (en) | 2002-09-12 | 2002-09-12 | High safety remote controller coding device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1414732A CN1414732A (en) | 2003-04-30 |
| CN1225096C true CN1225096C (en) | 2005-10-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02131636 Expired - Fee Related CN1225096C (en) | 2002-09-12 | 2002-09-12 | High safety remote controller coding device |
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| CN (1) | CN1225096C (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8151112B2 (en) * | 2005-04-22 | 2012-04-03 | Gerard Lin | Deliver-upon-request secure electronic message system |
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2002
- 2002-09-12 CN CN 02131636 patent/CN1225096C/en not_active Expired - Fee Related
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| CN1414732A (en) | 2003-04-30 |
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