CN101662363B - Multi-layer rolling code encryption and decryption technology - Google Patents

Abstract

The invention discloses a multi-layer rolling code encryption and decryption technology. In order to overcome the shortcomings of the existing similar encryption and decryption technology, such as poor anti-attack ability and poor applicability, the encryption algorithm of the present invention performs multi-layer nested rolling code encryption on the private key, manufacturer code, serial number, etc., and two synchronous count values. Computational processing to obtain the final output ciphertext; the decryption algorithm uses the secret key, the key generated by the manufacturer's code, and the serial number to decrypt the received ciphertext in two layers to obtain two synchronous counting values, and finally , respectively check the two synchronous count values, and if the matching requirements are met, the decryption is valid through the time window of the double synchronous count values. The present invention can be used in keyless access control systems of automobiles, warehouses, houses and other important places; it can also be used in data encryption transmission fields such as banks, securities and communications; the present invention has high reliability, good security, strong anti-attack ability and confidentiality High and easy to use.

Description

Multi-layer rolling code encryption and decryption technology

technical field

The invention relates to an encryption and decryption technology for encrypted transmission of data, in particular to a multi-layer rolling code encryption and decryption technology.

Background technique

Civilian point-to-point wireless or wired data transmission technology is widely used in keyless access control systems in automobiles, warehouses, housing and other important places; it can also be used in data encryption transmission fields such as banking, securities, and communications.

In recent years, the research on the codec IC security mechanism based on encryption algorithms has made great progress, which has promoted the development of civilian point-to-point data transmission coding technology from fixed codes to rolling codes, and basically eliminated the fixed code technology with poor confidentiality. The most successful typical representative is the KEELOQ technology of Microship Corporation of the United States, which has created a multi-variation (calculated by working 10 times a day, without sending repeated codes for 18 years), anti-interception, anti-copying, anti-coding scanning, and good security. , Non-linear rolling code encryption and decryption technology with high reliability (that is, single-layer rolling code encryption and decryption technology, whose representative chip is HCS300), is the preferred technology in the field of remote control keyless access control RKE in the world.

The fixed code has poor confidentiality and can be easily broken through simple copying or scanning techniques, which poses a huge security risk. Although the fixed code technology has been eliminated abroad, it is still widely used in some domestic places with low security requirements (including some important data transmission systems).

HCS300 based on KEELOQ nonlinear rolling code encryption and decryption technology (i.e. single-layer rolling code encryption and decryption technology) also has some shortcomings: first, the encrypted data of the chip must be written in advance, and the user's private information cannot be written later, which limits the scope of application , causing a lot of inconvenience in use; second, there are technical loopholes in HCS300, which endanger the security of confidentiality. For example: once the manufacturer's key (core key) leaks, it may cause a huge disaster that the entire system collapses. At the same time, there is also the possibility of exploiting its loopholes for replication, thus breaking its security key. For example, in 2007, a car theft gang in Northeast China broke through the access control of a certain model, and opened the door within 20 seconds, stealing nearly 100 vehicles in half a year; in 2008, there were also cases where the access control system of a certain model was breached in Guangdong and Hunan; The reason is that HCS300 does not have the function of bit error detection. In use, once a bit error occurs in data transmission, the consequences are also very serious.

Contents of the invention

Purpose of the present invention will overcome above-mentioned deficiency exactly, provide a kind of multi-layer rolling code encryption and decryption technology, use this encryption and decryption technology, the user can set up or revise privately conveniently, adopt privately and public secret (key, manufacturer's code, Serial number, etc.) two-layer protection, multi-layer nested rolling encryption transmission, higher reliability, better security, stronger anti-attack ability, higher confidentiality, and more convenient to use.

In order to achieve the above object, the technical solution of the present invention is that the multi-layer rolling code encryption and decryption technology includes the following steps:

(1) Encryption algorithm

a. Use the rolling code encryption algorithm to encrypt the synchronization count value 2 and secret with the top-level rolling code encryption to obtain the encrypted data 2;

b. Process the encrypted data 2 and the key with a key generation algorithm to obtain a new key;

c. Use the new key to encrypt the bottom layer rolling code on the synchronization count value 1 to obtain the final output ciphertext, that is, encrypted data 1;

d. The encrypted data 1, the information code and the serial number form the sending code and send it together.

(2) Decryption algorithm

a. Check the serial number;

b. Use the generation algorithm to process the secret, key, and manufacturer's code to generate a new key;

c. Use the new key generated in step b to decrypt the encrypted data 1 received by the decoder to obtain the synchronization count value 1 and the decrypted ciphertext at the bottom layer;

d. Perform top-level decryption processing on the bottom-level decrypted ciphertext with secret, and obtain a synchronization count value of 2;

e. Check the synchronization count value 1 and the synchronization count value 2. If the matching requirements are met, the decryption is valid through the double synchronization count value time window;

f. If the decryption is valid, execute the instruction indicated by the information code.

During the decryption process of the bottom layer and the top layer, a synchronization count value 1 and a synchronization count value 2 can be obtained respectively, and both of these two synchronization count values need to meet their respective time window matching requirements. Otherwise, the decryption process will be automatically terminated and the decryption will be invalid. The rotational angular velocities of the dual time windows are different. In this way, the confidentiality and anti-attack capability of the encryption and decryption system are greatly enhanced, and the time period for sending repetition codes is extended to hundreds of years.

The present invention is based on a group symmetric encryption algorithm, and combines multi-layer nesting and nonlinear rolling code technology, that is, a two-layer nested rolling code algorithm, the top layer is a private rolling code layer, and the bottom layer nests the private rolling code into a sequence number and The key generated by the manufacturer's code is used to form a new key, and then undergo rolling encryption processing to obtain the final code word sent.

In the process of two-layer nested rolling encoding, the double-synchronous count value encryption is used, and only when the time window requirements of the double-synchronous count value are met, the decoding can be carried out effectively.

The application of double synchronous counter value time window technology makes the time period of sending repeated codes theoretically extended to hundreds of years, which greatly exceeds the 18-year time of the existing (single-layer) rolling code technology. In this way, the encryption and decryption system is greatly enhanced. Confidentiality and anti-attack capabilities completely invalidate possible attack methods such as interception, copying, code scanning, and retransmission mechanisms.

The invention combines the double-layer 32-bit hopping code generated by the secondary non-linear encryption algorithm with the 24-bit serial number, 4-bit information code and flag bits to form a 64-bit coded word, and the private transmission adopts nested Rolling encryption is carried out (secondary non-linear rolling code encryption technology). The user's private participation in the encryption and decryption process of the multi-layer rolling code can effectively prevent the damage of the entire system from collapsing due to the leakage of public secrets (keys, manufacturer codes, serial numbers, etc.), and greatly improve the confidentiality and applicability of the system .

Keys, serial numbers and other important data used in the present invention are all stored in various types of memory designed in the CPLD chip, and cannot be accessed through any external connection, which can prevent any attempt to illegally steal information, and has high reliability. Good security and strong confidentiality.

Detailed ways

Example 1

The multi-layer rolling code encryption and decryption technology of the present invention can be implemented by CPLD/FPGA chips or other programmable devices, and the steps are as follows:

(1) Encryption algorithm

a. Use the rolling code encryption algorithm to encrypt the synchronization count value 2 and secret with the top-level rolling code encryption to obtain the encrypted data 2;

b. Process the encrypted data 2 and the key with a key generation algorithm to obtain a new key;

c. Use the new key to encrypt the bottom layer rolling code on the synchronization count value 1 to obtain the final output ciphertext, that is, encrypted data 1;

d. The encrypted data 1, the information code and the serial number form the sending code and send it together.

(2) Decryption algorithm

a. Check the serial number;

b. Use the generation algorithm to process the secret, key, and manufacturer's code to generate a new key;

c. Use the new key generated in step b to decrypt the encrypted data 1 received by the decoder to obtain the synchronization count value 1 and the decrypted ciphertext at the bottom layer;

d. Perform top-level decryption processing on the bottom-level decrypted ciphertext with secret, and obtain a synchronization count value of 2;

e. Check the synchronization count value 1 and the synchronization count value 2. If the matching requirements are met, the decryption is valid through the double synchronization count value time window;

f. If the decryption is valid, execute the instruction indicated by the information code.

Claims (1)

1. A multi-layer rolling code encryption and decryption method is characterized in that it comprises the steps: (1) Encryption steps a. Use the rolling code encryption algorithm to perform the top-level rolling code encryption processing on the synchronization count value 2 and the secret, and obtain the encrypted data 2; b. Process the encrypted data 2 and the key with a key generation algorithm to obtain a new key; c. Use the new key generated in step b to perform the underlying rolling code encryption process on the synchronization count value 1 to obtain the final output ciphertext, that is, the encrypted data 1; d. The encrypted data 1 forms a sending code with the information code and the serial number and sends them together; (2) Decryption steps e. Check the serial number; f. Use the generation algorithm to process the secret, key, and manufacturer's code to generate a new key; g. use the new key generated by step f to decrypt the encrypted data 1 received by the decoder, and obtain the synchronization count value 1 and the decrypted ciphertext at the bottom layer; h. Perform top-level decryption processing on the bottom-level decrypted ciphertext with secret, and obtain a synchronization count value of 2; i. Check the synchronous count value 1 and the synchronous count value 2, if the matching requirements are met, the decryption is valid through the double synchronous count value time window; j. If the decryption is valid, execute the instruction represented by the information code.