Device and method for maintenance filtering on a flow of coded inputs/outputs

1. A maintenance filtering method for maintenance filtering on a flow of m successive incoming messages Es j to be received at an input of a maintenance filtering device which is a hardware machine configured for processing the incoming messages Es j in order to generate an outgoing message Esm j at its output from each incoming message Es j ,

wherein each incoming message Es j includes:

a set of n j Inputs/Outputs es i,j (i=1, . . . , n j ), each of which can be characterized by s i states P q,i,j , each state P q,i,j being associated with a value v q,i,j to which the Input/Output es i,j is equal when in the state P q,i,j ;

a checksum ΣSes i,j of signatures Ses i,j , each signature Ses i,j being intended to code the Input/Output es i,j ; and

a date d j dating the checksum, the date being incremented by a date increment at each incoming message;

the maintenance filtering method comprising:

generating by the maintenance filtering device and from each incoming message Es j the outgoing message Esm j , such that the outgoing message Esm j includes:

a set of n j Inputs/Outputs esm i,j , each of which can be characterized by the s i states P q,i,j , a value v q,i,j of the Input/Output esm i,j of the outgoing message Esm j being equal to or different from the value v′ q,i,j of the Input/Output es i,j of the incoming message Es j as a function of possible maintenance of the state P q,i,j of the Input/Output es i,j ;

a checksum ΣSesm i,j of signatures Sesm i,j , each signature Sesm i,j being intended to code the Input/Output esm i,j as a function of a state of the Input/Output es i,j ; and

the date d j ;

and thereby calculating, using a calculation device, each checksum ΣSesm i,j of the outgoing message Esm j by adding at least one compensation to the checksum ΣSes i,j , the compensation being calculated as a function of a current state of a pseudo-random generator and an item taken from a compensation table.

2. The maintenance filtering method according to claim 1 , which comprises coupling the pseudo-random generator with a date extraction device capable of extracting at least one signature of a checksum.

3. The maintenance filtering method according to claim 1 , which comprises splitting the checksum ΣSesm i,j into c fields, with c being greater than or equal to 2.

4. The maintenance filtering method according to claim 1 , which comprises, prior to receiving a first incoming message Es 1 , initializing at least one pseudo-random generator for generating by way of the pseudo-random generator an initialization value capable of processing solely one state of an Input/Output intended not to be maintained.

5. The maintenance filtering method according to claim 1 , which comprises, from the first incoming message Es 1 and for each consecutive incoming message Es j :

if the Input/Output es i,j is in a state intended not to be maintained, executing a short LSFR cycle run by the pseudo-random generator associated with the Input/Output es i,j ;

if the Input/Output es i,j is in a state intended to be maintained, executing a long LSFR cycle run by the pseudo-random generator associated with the Input/Output es i,j .

6. The maintenance filtering method according to claim 5 , wherein the run of the short LSFR cycle and the run of the long LSFR cycle each comprises an addition, successively for each field of the checksum ΣSes i,j , of the field of the checksum ΣSes i,j to a value characterizing the current state of the pseudo-random generator and to the item originating from the compensation table.

7. The maintenance filtering method according to claim 1 , wherein the item originating from the compensation table is pre-defined as a function of the Input/Output es i,j , its state and the checksum ΣSes i,j in order to provide for either a generation of a check signature Sesm i,j characterizing a maintenance of the state of an Input/Output for a period T i , or a generation of a check signature Sesm i,j characterizing a confirmation of the state of an Input/Output of an incoming message.

8. The maintenance filtering method according to claim 1 , which comprises verifying a date increment between two consecutive messages.

9. A maintenance filtering device being a hardware machine for processing a flow of m incoming messages Es j in order to generate from each incoming message Es j an outgoing message Esm j

each incoming message Es j including:

n j Inputs/Outputs es i,j ,

a checksum ΣSes i,j of signatures Ses i,j , each signature Ses i,j being intended to code the Input/Output es i,j , and

a date d j ;

the outgoing message Esm j including:

n j Inputs/Outputs esm i,j ,

a checksum ΣSesm i,j of signatures Sesm i,j , each signature Sesm i,j being intended to code said Input/Output esm i,j , and

the date d j ;

the filtering device being configured to maintain at least one state of at least one Input/Output es i,j of at least one of the incoming messages Es j for a period of time Ti whatever a state of an i th Input/Output of an incoming message consecutive to the incoming message Es j by generating at least one outgoing message characterized in that the state of the i th Input/Output of the outgoing message is equal to the state of the Input/Output es i,j of the incoming message Es j , and the filtering device comprising:

a calculation device configured for calculating for each incoming message Es j from the checksum ΣSes i,j and by adding at least one compensation to the checksum ΣSes i,j , a checksum ΣSesm i,j intended to characterize the outgoing message Esm j ;

at least one pseudo-random generator with a current state intended to calculate the compensation; and

at least one compensation table for calculating the compensation.

10. The maintenance filtering device according to claim 9 , wherein said calculation device, each said pseudo-random generator, and each said compensation table are coupled with one another in order to generate the compensation.

11. The maintenance filtering device according to claim 9 , wherein said calculation device comprises at least one hardwired algorithm.

12. The maintenance filtering device according to claim 9 , further comprising a date extraction device to be coupled to said pseudo-random generator.

13. The maintenance filtering device according to claim 9 , wherein the compensation table comprises predetermined data, each item of data being predefined as a function of a current state of the pseudo-random generator, the Input/Output es i,j , of a state thereof and the check signature Ses i,j in order to provide for either a generation of a check signature Sesm i,j characterizing a maintenance of the state of an Input/Output for a period T i , or a generation of a check signature Sesm i,j characterizing a confirmation of the state of an Input/Output of an incoming message.

14. The maintenance filtering device according to claim 9 , which further comprises at least one adder.

15. The maintenance filtering device according to claim 9 , further comprising a date extraction device configured for extracting the date of at least one checksum, an incoming message or an outgoing message, and of determining a date increment between two successive messages processed by the maintenance filtering device.