CN1384632A - Communication message safety ensuring method and device for CDMA communication system - Google Patents
Communication message safety ensuring method and device for CDMA communication system Download PDFInfo
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- CN1384632A CN1384632A CN01115693A CN01115693A CN1384632A CN 1384632 A CN1384632 A CN 1384632A CN 01115693 A CN01115693 A CN 01115693A CN 01115693 A CN01115693 A CN 01115693A CN 1384632 A CN1384632 A CN 1384632A
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Abstract
The method of ensuring communication message safety in CDMA communication system includes the following steps: encoding input analog signal into information bits with preset length and creating grouped voice coder information bits; enciphering the encoded and grouped voice coder information bits with grouped cipher and safe cipher key; adding frame quality indicating sign and encoder tail bit behind the ciphered grouped voice coder information bits to constitute CDMA frame; and treating the CDMA frame via convolutional coding, crossed treatment and bandspread modulation in specified frequency band before sending to base station.
Description
The present invention relates to a kind of cdma communication system, more particularly, relate to a kind of method and apparatus that is used for guaranteeing at cdma communication system communication message safety, it makes system can carry out the privacy communication under the situation that prevents to eavesdrop.
In meeting the traditional C DMA communication system of IS-95 standard, caller's sound is encoded into information bit by vocoder (vocoder) through digital processing with after compressing, and obtains modulation in reverse channel communication.Modulation signal is transmitted to the base station.The modulation signal that obtains in the base station is reduced into original information bits in forward communication channels, be decoded into original speech by vocoder then.By said process, just can between long-range travelling carriage, communicate.
But traditional cdma system has a shortcoming, that is, as long as just can be detected in base station or switch by the information bit of this vocoder, and detected information bit can be decoded into original speech easily.Therefore, traditional cdma system has the shortcoming of easily being eavesdropped.
U.S. Patent No. 5,727,064 has disclosed a kind of technology that is used to solve above-mentioned shortcoming, and this technology has increased a scrambler on long key generator.But this technology can not be applied in the traditional C DMA system of not doing any change, because it need make amendment to IS-95 CDMA equipment, and it is limited to and can only communicates between the different user group who uses different safe keys.
An object of the present invention is to provide a kind of apparatus and method that are used for guaranteeing communication message safety at cdma communication system, it makes system carry out the privacy communication under the situation that prevents to eavesdrop or monitor, and need not simultaneously the traditional base station and the switching system that meet the IS-95 standard are made amendment.
For achieving the above object, the invention provides a kind of device that is used for guaranteeing communication message safety at cdma communication system, this device comprises: encoder is used for input signal is compressed into the information bit with predetermined length and generates the vocoder packets information bit; Encryption equipment is used for the vocoder packets information bit that generates from above-mentioned encoder is encrypted; The CDMA framer, it adds incoming frame quality indicator and Encoder Tail Bits in the encryption vocoder packets information bit of above-mentioned encryption equipment output, thereby constitutes the CDMA frame; CDMA frame reflector is transmitted to the base station after its frequency band by appointment passes through convolutional encoding processing, staggered processing and band spectrum modulation successively with the CDMA frame; The CDMA frame grabber is used to receive the signal that sends the base station and the CDMA frame is reduced; The CDMA deframer is used for extracting the vocoder packets information bit of encrypting from the CDMA frame that is restored by above-mentioned CDMA frame grabber; Decipher is used for the encryption vocoder packets information bit that is extracted by above-mentioned CDMA deframer is decrypted; And decoder, be used for and will decode from the vocoder packets information bit through deciphering of above-mentioned decipher output.Wherein, above-mentioned encryption equipment utilizes block cipher and safe key to come the vocoder packets information bit is encrypted, and above-mentioned decipher then utilizes above-mentioned block cipher and comes the vocoder packets information bit is decrypted with the total safe key of the other side's travelling carriage.
In addition, for achieving the above object, the invention provides a kind of method that is used for guaranteeing at cdma communication system communication message safety, this method may further comprise the steps: analog input signal is encoded into the information bit with predetermined length, and generates the vocoder packets information bit; Utilize block cipher and safe key that above-mentioned encoded vocoder packets information bit is carried out block encryption; In encrypted vocoder packets information bit, add incoming frame quality indicator and Encoder Tail Bits to constitute the CDMA frame; And the frequency band by appointment with the CDMA frame successively through convolutional encoding handle, staggered handle and band spectrum modulation processing after, be transmitted to the base station.
For achieving the above object, the present invention also provides a kind of method that is used for guaranteeing at cdma communication system communication message safety, and this method may further comprise the steps: receive the signal that sends from the base station; It is reduced into the CDMA frame; From the CDMA frame that restores, extract the vocoder packets information bit of encrypting; Utilize block cipher and safe key that the vocoder packets information bit of encrypting is decrypted; And to decoding through the vocoder packets information bit of deciphering.
By following explanatory note also with reference to the accompanying drawings, it is clear more understandable that the features and advantages of the present invention will become, in the accompanying drawings:
The block diagram of Fig. 1 has shown according to communication channel of the present invention;
Fig. 2 has shown a kind of DES algorithm of the present invention that is applicable to;
Fig. 3 has shown a single iteration in the DES algorithm shown in Figure 2;
The flow chart of Fig. 4 has shown described in accordance with a preferred embodiment of the present invention encryption/transmission course;
The flow chart of Fig. 5 has shown described in accordance with a preferred embodiment of the present invention reception/decrypting process;
1. oppositely/structure of forward communication channels
The block diagram of Fig. 1 has shown according to communication channel of the present invention.In Fig. 1, chain-dotted line has been indicated major part of the present invention.
Below with reference to Fig. 1 reverse communication channel is described.
After the digitized processing compression, be encoded into vocoder packets information bit 141 by a vocoder 100 from the voice of microphone input, and be sent to encryption equipment 140.Encryption equipment 140 utilizes all or part of vocoder packets information bit 143 of encrypting and produce encryption of the vocoder packets information bit 141 that block cipher 170 (as DES or three DES) exports vocoder, sends it to CDMA framer 110 then.Used safe key 160 in ciphering process, it is stored in the encryption equipment 140 or in a kind of safe mode and is exchanged.CDMA framer 110 is carried out in vocoder packets information bit 142 backs of encrypting and is added a frame quality indicator and Encoder Tail Bits to constitute the process of CDMA frame.
Next will describe with reference to 1 pair of forward communication channel of figure.
Is that unit carry out according to block cipher 170 with the byte to the encryption of vocoder packets information bit 141 and to the deciphering of the vocoder packets information bit 152 encrypted, therefore, have only with 8 integral multiple information corresponding bit just can encrypted or deciphering.
For example, in IS-95A 9600bps frame because the number of information bit be 172 (=8 * 21+4), thus have only 21 bytes encrypted/deciphering.But, when the amount of calculation in preset time too many so that can not carry out encrypt/decrypt the time, then will have only a part (for example, 8 bytes) wherein to obtain encrypt/decrypt.In addition, when the output of vocoder 100 is one quiet (1/8 speed),, then can omit encryption in order to prevent noise.Like this after vocoder is finished coding, encryption equipment 140 and decipher 150 can utilize software or hardware and carry out an encrypt/decrypt every 20ms.
As for encrypt/decrypt, can select for use FIPS PUB 46 (Federal Information Processing Standards 46) that the NIST (national standard and Institute for Research and Technology) of the U.S. provided with as DES (data encryption standard).
Fig. 2 has shown a kind of DES algorithm of the present invention that is applicable to, Fig. 3 has shown a single iteration in the DES algorithm of 64 texts of employing shown in Figure 2 and 56 safe keys.In this case, for example, can think and have only preceding 8 in 172 to obtain encrypt/decrypt.Like this, 64 plain texts (for example, 01 23 45 67 89 ab cd e7) will be corresponding to from 172 vocoder packets information bits of vocoder 100 output preceding 8 shown in Figure 2, and 56 keys among Fig. 2 (for example, 01 23 45 67 89 ab cd) then represent safe key, this safe key is total by sending station and receiving platform.172 are encrypted the vocoder packets information bit is by 108 64 cryptograms (for example, c9 57 44 25 6a 5e d3 1d) additions with encryption equipment 140 of remaining unencrypted are obtained.
Below will the decrypting process as the ciphering process inverse process be described.
By to 8 encrypted bytes in the vocoder packets information bit of 172 encryptions of CDMA deframer 120 outputs (promptly according to the order opposite with ciphering process, 64 cryptograms among Fig. 2 (for example, c9 57 44 25 6a 5e d3 1d)) and 56 keys among Fig. 2 (for example, 01 23 45 67 89 ab cd) be decrypted, just can obtain 64 original plain texts (for example, 01 23 45 67 89 ab cd; With reference to figure 4).By remaining 108 172 vocoder packets information bits that generate with 64 plain text additions are sent to vocoder 130, and obtain decoding therein to restore original speech.
Used block cipher in the above-mentioned encryption such as DES and triple des.3. setting/the releasing of safe mode
Concerning the mobile communication that can not adopt above-mentioned safe mode, if when the communication beginning, have a predetermined key to be transfused to, then sending station will be placed in safe mode setting or disarm state, and receiving platform also can be placed in safe mode setting or the disarm state identical with sending station.So just can make remote station can prevent to carry out safe privacy communication under the situation of eavesdropping.This safe mode setting/releasing with specific key can be performed before call setting, also can carry out during conversing after call setting is finished.
The implementation of setting the safe mode startup is as follows.The ON key of a request startup safe mode is transfused to into reverse channel communication.Then, one starts corresponding first yard type (different with the vocoder speech) and information bit with safe mode and is sent to other travelling carriage.The other side's travelling carriage receives and checks that this first yard type is to place safe mode ON (startup) state.
The implementation of closed safe pattern is as follows.Import an OFF key in communication period, and send to other travelling carriage with the corresponding second yard type of releasing safe mode (different) information bit with the voice that carry out the processing of sound sign indicating number with one.The other side's travelling carriage receives and checks this second yard type safe mode being placed OFF (closing) state, and is back to normal mode subsequently.In addition, when sign off, safe mode also can be automatically made OFF.Utilize this method, just can repeat the setting/releasing of safe mode in communication period.
In light current ripple zone, be sent out mistake may occurring in the sign indicating number type that is used to set/remove safe mode, and can make receiving platform can not be placed in the startup or the closed condition of safe mode thus.Like this, receiving platform is placed in safe mode and closes because sending station is placed in that safe mode starts, thereby just can not communicate each other.Can adopt following method to solve this problem: 1) to repeat to send safe mode startup/shutdown signal to reduce wrong appearance; Or 2) when sending station to receiving platform emission security pattern startup/shutdown signal and when communicating by letter mutually, by sending an ECHO (response) signal so that the reception of safe mode startup/shutdown signal is informed to sending station to sending station from receiving platform, sending station detects the ECHO signal that sends from receiving platform afterwards, and the startup of setting safe mode/close.
The ON key that is used for setting safe mode and starts/close is can not influence the key of communicating by letter from those to choose with the OFF key.In addition, be set in safe mode under the situation of ON, safe key in the block cipher can be launched with the ON key, perhaps also can be launched away together with a scheme that is used to find out the safe key that can launch with the ON key, and this will obtain explanation in the back.4. quiet control
Usually get on very well the quiet situation that is illustrated in the electrical power of speech in the 20ms less than fiducial value (detection) less than speech.Under quiet situation, the decrypting process in ciphering process in the encryption equipment 140 and the decipher 150 can be skipped by signal MUTE_TX 143 or MUTE_RX153, and in addition, they also can be skipped by signal Security_Mode 180 according to safe mode.
Table 1. encryption equipment with safe mode and quiet serve as according to performed operation
Table 2. decipher with safe mode and quiet serve as according to performed operation
Table 1 and table 2 have shown that respectively encryption equipment and decipher are according to safe mode and quiet performed operation.Reference table 1 and table 2, when signal Security_Mode 180 was OFF, encryption equipment 140 and decipher 150 were skipped entirely.In addition, though Security_Mode 180 is set at ON, when signal MUTE_Tx 143 or MUTE_Rx 153 were ON, encryption equipment 140 and decipher 150 were also skipped entirely.
Under the situation of fixed rate, when appearance is quiet, do not need independent process.But under the situation of variable bit rate, when appearance is quiet, vocoder packets will be handled by the ratio with 1/8, so just can check out the mute state of frame under the situation that does not need any special process simply.Therefore, adopt a kind of new logic to realize the present invention with regard to need not.5. total safe key
Because the block cipher of encryption equipment 140 and decipher 150 has used identical algorithm and identical safe key.Therefore, need a kind of can mutually away from transmitter and receiver between the scheme of total safe key.
The first string is to send a safe key from sender to receiver when being set at safe mode.For example, when safe mode is set to ON, the special code type that the information of 172 bits in IS-95 9600bps frame is set at Security_Mode as a representative (for example, in the hexadecimal 5555 ... 555) be sent out away, then, 128 bits (if safe key is 128) in the next frame are defined as a safe key, and perhaps safe key of encrypting through master key (it is commonly referred to as be a session key and be disposable) is sent out away.Under the situation of using master key, the travelling carriage in the communication is having identical master key, and it is stored in the tissue that is authorized to.
Second scheme is when being set at safe mode, specifies a key (for example, 100 128 key) that is kept in an identical manner in transmitter and the receiver.In other words, in 172 information bits of an IS-95 9600bps frame, for example, wherein 164 are used as one and represent special code type that safe mode opens (for example, in the hexadecimal 5555 ... 555), remaining 8 index that then are used as secret 256 safe keys preserving.At this moment, the safe key of preservation can be configured to the safe key that travelling carriage manufacturer provided and the safe key of user oneself input.
The 3rd scheme is two users to be called out by another one only exchange " safe key ".Wait that the safe key that is exchanged can obtain by user's input or by a randomizer in the travelling carriage.When being set at safe mode, can specifying and use by second scheme according to the safe key of the 3rd scheme exchange.6. encryption/transmission course
The flow chart of Fig. 4 has shown encryption/transmission course in accordance with a preferred embodiment of the present invention.Below with reference to Fig. 4 ciphering process is elaborated.
At first, when the power supply electrifying of reflector, the initialization procedure in the reflector is performed (step 400).Then, when the user imports a key and calls out with request (step 405), will set up calling (step 410).At this moment, if being safe mode, the key of input starts key (step 415 and 420), then the safe mode of reflector will be placed in ON (step 425), and the index of the expression special code type of Security_ON and a safe key of choosing from a plurality of safe keys of reflector is added in the information bit in the communication channel (step 430).
If the key of input is that safe mode is closed key (step 415 and 420), then the safe mode of reflector will be placed in OFF (step 435), and the special code type of representing Security_OFF then is added to (step 440) among the information bit in the communication channel.
If do not import the safe mode key in step 415, then vocoder will be encoded into input signal the information bit of specific length and generate vocoder packets information bit (step 445).If safe mode is ON (step 450) and vocoder packets information bit is not quiet (step 455), then the vocoder packets information bit will utilize block cipher and safe key to encrypt (step 460).Otherwise step 455 and 460 will be skipped.In the CDMA framer, frame quality indicator and Encoder Tail Bits are added in into encryption or the unencrypted vocoder packets information bit to constitute a CDMA frame (step 465), then this CDMA frame successively through convolutional encoding, staggered handle and the band spectrum modulation process and finally the frequency band by an appointment be transmitted to a base station (step 470).In step 475, if keep conversation, then flow process is back to step 415.If conversation finishes, then safe mode is set back normal mode (step 480), and flow process will be back to step 405 continuation execution.
Each function available software relevant with decipher with encryption equipment of the present invention realizes that also available hardware such as ASIC (application-specific integrated circuit (ASIC)) is realized.7. reception/decrypting process
The flow chart of Fig. 5 shown with the corresponding receiver of reflector shown in Figure 4 on described in accordance with a preferred embodiment of the present invention reception/decrypting process of carrying out.Below with reference to Fig. 5 this reception/decrypting process is elaborated.
At first, when the receiver energized, the initialization procedure in the receiver is performed (step 500).Then, when receiving ring and calling (step 505), the conversation between reflector and the receiver is established (step 510).Afterwards, receiver receives a modulation signal that sends from the base station and restore CDMA frame (step 515) from this signal.The CDMA deframer extracts an encrypted vocoder packets information bit (step 520) from the CDMA frame that restores.Decipher judges in the vocoder packets information bit of encryption whether contain safe mode sign indicating number type (step 525).If this safe mode sign indicating number type is represented Security_Mode ON (step 530), then decipher is with the index that is contained in the inspection message bit, and in a plurality of safe keys of receiver, determine the safe key (step 535) corresponding with this index, the safe mode of receiver is set to ON (step 540) then.In step 530, if the safe mode sign indicating number type in the information bit is represented Security_ModeOFF, then the safe mode of receiver is set to OFF (step 545).
When the vocoder packets information bit does not contain under the situation of safe mode sign indicating number type in step 525, if the safe mode of receiver is that the vocoder packets information bit of ON (step 550) and encryption is not quiet (step 555), then decipher will utilize block cipher and safe key that the vocoder packets information bit of encrypting is decrypted (step 560).Otherwise step 555 and 560 will be skipped (step 550,555,560).To be subjected to the decoding (step 565) of vocoder through the vocoder packets information bit of deciphering or skip.
In step 570, if conversation is maintained, then flow process is returned to step 515.If conversation finishes in step 570, then safe mode is set back normal mode (step 575), and flow process will be back to step 505.
Each function relevant with decrypting process of the present invention be available software or realize such as the hardware of ASIC (application-specific integrated circuit (ASIC)) also.
As mentioned above, the present invention can utilize block cipher to carry out ciphering process between the vocoder of reverse channel communication and CDMA framer, and can utilize block cipher to carry out decrypting process between the vocoder of forward communication channels and CDMA deframer.
Therefore, because information bit transmits with a kind of encrypted form (except that reflector and receiver), even so coded information bits by the detected situation of a kind of advanced techniques under, also can not under inaccuracy is known the situation of algorithm and safe key, the information encrypted bit be decrypted into original vocoder packets.
In addition, the present invention has such advantage, that is, it can make cdma system carry out the privacy communication that can't eavesdrop under the situation that need not to revise the traditional base station that meets the IS-95 standard and switching system.
The present invention also provides a kind of simple and safe method to be used for the total of safe key, just can communicate between the different user group who uses different safe keys thus.Thereby can between a plurality of little customer groups, set up secure network rapidly.
To explanation of the present invention is to carry out with the form of preferred embodiment.But, should be understood that application of the present invention is not limited in these certain embodiments.It will be recognized by those skilled in the art, can not break away from the spirit and scope of the present invention that define by following claim various modifications of the present invention and conversion.
Claims (26)
1. device that is used for guaranteeing in code division multiple access (CDMA) communication system communication message safety is characterized in that comprising:
Encoder is used for input signal is compressed into the information bit of predetermined length, and generates the vocoder packets information bit;
Encryption equipment is used for the vocoder packets information bit that generates from above-mentioned encoder is carried out block encryption;
The CDMA framer adds incoming frame quality indicator and Encoder Tail Bits in the vocoder packets information bit of the encryption that above-mentioned encryption equipment is exported, thereby constitutes the CDMA frame;
CDMA frame reflector, the frequency band by appointment with the CDMA frame successively through convolutional encoding, staggered handle and the band spectrum modulation process after to base station;
The CDMA frame grabber is used to receive the signal that sends the base station and reduces described CDMA frame;
The CDMA deframer is used for extracting the vocoder packets information bit of encrypting from the CDMA frame that is restored by above-mentioned CDMA frame grabber;
Decipher is used for the encryption vocoder packets information bit that is extracted by above-mentioned CDMA deframer is decrypted; And
Decoder is used for and will decodes from the vocoder packets information bit through deciphering of above-mentioned decipher output,
Wherein, above-mentioned encryption equipment utilizes block cipher and safe key to come the vocoder packets information bit is encrypted, and above-mentioned decipher then utilizes above-mentioned block cipher and comes the vocoder packets information bit is decrypted with the total safe key of the other side's travelling carriage.
2. device as claimed in claim 1 is characterized in that above-mentioned block cipher is DES.
3. device as claimed in claim 1 is characterized in that above-mentioned encryption equipment can set or remove encryption according to the safe mode of user input.
4. device as claimed in claim 3, it is characterized in that above-mentioned encryption equipment can generate with the setting of safe mode or removes corresponding predetermined codes type, the above-mentioned predetermined codes type that generates is added in the information bit of communication channel and send it to other travelling carriage, deciphering be set or be removed to above-mentioned decipher then can according to above-mentioned predetermined codes type.
5. device as claimed in claim 4, it is characterized in that when being set at described safe mode, above-mentioned encryption equipment can add safe key in the information bit of communication channel, and the above-mentioned decipher then above-mentioned safe key that is contained in the information bit of communication channel of available packages is decrypted the vocoder packets information bit of encrypting.
6. device as claimed in claim 4, it is characterized in that when being set at above-mentioned safe mode, above-mentioned encryption equipment can utilize a master key that described safe key is encrypted, and the safe key of encrypting can be added in the information bit of communication channel, the then available above-mentioned master key of above-mentioned decipher is decrypted the safe key of the encryption in the information bit that is included in communication channel, and utilizes the safe key through deciphering that the vocoder packets information bit of encrypting is decrypted.
7. device as claimed in claim 4, it is characterized in that above-mentioned encryption equipment is furnished with a plurality of safe keys, and can work as when being set at described safe mode, the index that in the information bit of communication channel, adds the safe key of from a plurality of safe keys, choosing, and the available safe key that this is chosen is encrypted the vocoder packets information bit, and the total a plurality of safe keys of above-mentioned decipher and above-mentioned encryption equipment, and can utilize safe key that the index that comprises in the information bit according to communication channel chooses that the vocoder packets information bit of described encryption is decrypted.
8. device as claimed in claim 1, it is characterized in that the above-mentioned encoder in the described reverse channel communication can produce whether the vocoder packets information bit of representing generation is quiet signal MUTE_Tx, if MUTE_Tx represents quiet, then above-mentioned encryption equipment will not encrypted the vocoder packets information bit, whether the vocoder packets information bit that above-mentioned CDMA deframer produces the expression encryption is quiet signal MUTE_Rx, if MUTE_Rx represents quiet, then above-mentioned decipher will not be decrypted the vocoder packets information bit of encrypting.
9. device as claimed in claim 1 it is characterized in that above-mentioned encryption equipment encrypts all or part of of vocoder packets information bit, and above-mentioned decipher is decrypted to all or part of of vocoder packets information bit.
10. method that is used for guaranteeing in code division multiple access (CDMA) communication system communication message safety may further comprise the steps:
Input signal is encoded into the information bit with predetermined length, and generates the vocoder packets information bit;
Utilize block cipher and safe key that above-mentioned encoded vocoder packets information bit is encrypted;
Behind encrypted vocoder packets information bit, add incoming frame quality indicator and Encoder Tail Bits to constitute the CDMA frame; And
Frequency band by appointment with the CDMA frame successively through convolutional encoding, staggered handle and band spectrum modulation after be transmitted to the base station.
11. method as claimed in claim 10, wherein above-mentioned block cipher is DES.
12. method as claimed in claim 10, wherein above-mentioned encrypting step comprise the step of setting or remove encryption according to the safe mode of user's input.
13. method as claimed in claim 12 is characterized in that above-mentioned encrypting step comprises to generate with the setting of safe mode and remove corresponding predetermined codes type and the sign indicating number type that generates is added to step in the information bit of communication channel.
14. method as claimed in claim 13 is characterized in that above-mentioned encrypting step comprises when being set at safe mode, above-mentioned safe key is added to the step in the information bit of communication channel.
15. method as claimed in claim 13 is characterized in that above-mentioned encrypting step comprises when being set at safe mode, utilizes a predetermined master key that safe key is encrypted, and the safe key of encrypting is added to the step in the information bit of communication channel.
16. method as claimed in claim 13, it is characterized in that above-mentioned encrypting step comprises the steps: when being set at safe mode, in the information bit of communication channel, add the safe key index of from a plurality of safe keys, choosing, and utilized this safe key of choosing that above-mentioned vocoder packets information bit is encrypted.
17. method as claimed in claim 10, it is characterized in that above-mentioned encrypting step comprises the steps: whether the vocoder packets information bit to generating is quiet the detection, and when detecting mute state, the vocoder packets information bit is not being encrypted.
18. method as claimed in claim 10 is characterized in that above-mentioned encrypting step comprises the step of only a part of information bit of vocoder packets information bit being encrypted.
19. a method that is used for guaranteeing in code division multiple access (CDMA) communication system communication message safety may further comprise the steps:
The signal that reception is sent from the base station, and it is reduced into the CDMA frame;
From the CDMA frame that restores, extract the vocoder packets information bit of encrypting;
Utilize block cipher and safe key that the vocoder packets information bit of encrypting is decrypted; And
To decoding through the vocoder packets information bit of deciphering.
20. method as claimed in claim 19 is characterized in that above-mentioned block cipher is DES.
21. method as claimed in claim 19, it is characterized in that above-mentioned decryption step comprises the steps: to set or the releasing safe mode according to the predetermined codes type in the grouping information bit that is included in the communication channel that receives, and determine whether to carry out decrypting process according to described safe mode.
22. method as claimed in claim 21 is characterized in that when being set at safe mode, above-mentioned safe key is included in the middle of the information bit that receives from communication channel.
23. method as claimed in claim 21 is characterized in that when being set at safe mode, with predetermined master key the above-mentioned safe key that comprises the information bit that receives from communication channel is decrypted.
24. method as claimed in claim 21 is characterized in that when being set at safe mode, determines described safe key according to the index in the information bit that is included in communication channel from a plurality of safe keys that travelling carriage is furnished with.
25. method as claimed in claim 19, it is characterized in that above-mentioned decryption step comprises the steps: whether the vocoder packets information bit to generating is quiet the detection, and when detecting mute state, the vocoder packets information bit be not decrypted.
26. method as claimed in claim 19 is characterized in that above-mentioned decryption step comprises the step that only encrypted a part of information bit in the vocoder packets information bit of encrypting is decrypted.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011156937A CN1193530C (en) | 2001-04-29 | 2001-04-29 | Communication message safety ensuring method and device for CDMA communication system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011156937A CN1193530C (en) | 2001-04-29 | 2001-04-29 | Communication message safety ensuring method and device for CDMA communication system |
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| Publication Number | Publication Date |
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| CN1384632A true CN1384632A (en) | 2002-12-11 |
| CN1193530C CN1193530C (en) | 2005-03-16 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB011156937A Expired - Fee Related CN1193530C (en) | 2001-04-29 | 2001-04-29 | Communication message safety ensuring method and device for CDMA communication system |
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| Country | Link |
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| CN (1) | CN1193530C (en) |
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| CN1193530C (en) | 2005-03-16 |
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