DE102023102691A1 - Method for writing data to an IC and system for carrying out the method - Google Patents

Abstract

The invention relates to a method for writing data to an IC 3 with the following steps: 1. Providing a data packet in encrypted form containing the data to be written to the IC 3; 2. Loading the encrypted data packet; 3. Decrypting the encrypted data packet and storing the decrypted data packet exclusively in a volatile memory 10; 4. Providing the decrypted data packet in the volatile memory 10 for a programming machine 6; 5. Writing one or more ICs 3 with data of the decrypted data packet intended for the IC 3 using the programming machine 6; 6. After completing the writing of the or more ICs 3: erasing the volatile memory 10.

Description

The invention relates to a method for writing data to an IC and a system for carrying out this method.

ICs are an essential component in electronic products. They are used to carry out a wide variety of tasks, such as receiving and evaluating data and/or carrying out certain actions depending on conditions that control the peripherals of an IC. They can also be used to store data.

Due to increasing digitalization, such ICs also take on security-relevant tasks, such as storing personal, security-relevant data, such as smart cards, bank cards, etc., or carrying out security-relevant and critical actions, for example in the automotive sector. To take on these tasks, the IC is described with a so-called image. The information that is used to describe an IC with the personal data or to carry out security-relevant actions is generally referred to as data below.

ICs can be designed as EPROM, EEPROM or similar, although the invention is not limited to this. It is important that the IC used can be written to with the data intended for it in a programming machine.

To counteract the potential of a possible attack, the data intended for the IC, which is usually developed in a development department, must be securely transferred to a programming machine that describes the IC(s). Data should also not be accessible to a third party afterwards - for example, after the IC has been written to. This is usually the case when the data is (temporarily) stored on a non-volatile memory.

In order to securely transmit the data intended for the IC, it is usually transmitted encrypted and can only be decrypted with a corresponding key.

Out of US 2007/0038851 A1 A programming machine is known that is suitable for writing safety-relevant data to an IC. The safety-relevant data is stored in a volatile memory of the programming machine. This data is then used to write to an IC.

Even if it is not possible to access the data after writing to the IC on this known programming machine itself due to the use of a volatile memory, the data must be available in decrypted form for the programming machine to write to the IC, or must be transferred to it in decrypted form. This entails the risk that the data is (temporarily) stored in a non-volatile memory during transmission to the programming machine and can be accessed later without being noticed, especially since such programming machines are usually connected to a large computer network (such as a LAN).

Against this background, the object of the invention is to propose a method with which the security of the process for writing data to an IC is increased. In addition, the object of the invention is to propose a retrofittable system for carrying out the method.

1. 1. Bereitstellen eines in verschlüsselter Form vorliegenden Datenpakets, enthaltend die auf den IC zu schreibenden Daten;
2. 2. Laden des verschlüsselten Datenpakets;
3. 3. Entschlüsseln des verschlüsselten Datenpaketes und Ablegen des entschlüsselten Datenpaketes ausschließlich in einem flüchtigen Speicher;
4. 4. Bereitstellen des entschlüsselten Datenpakets in dem flüchtigen Speicher für eine Programmiermaschine;
5. 5. Beschreiben eines oder mehrerer ICs mit für den IC bestimmten Daten des entschlüsselten Datenpakets mittels der Programmiermaschine;
6. 6. Nach dem Fertigstellen des Beschreibens des bzw. der mehreren ICs: Löschen des flüchtigen Speichers.

The method-related task is solved by a method for writing data to an IC with the following steps:

1. 1. Providing a data packet in encrypted form containing the data to be written to the IC;
2. 2. Loading the encrypted data packet;
3. 3. Decrypting the encrypted data packet and storing the decrypted data packet exclusively in a volatile memory;
4. 4. Providing the decrypted data packet in the volatile memory to a programming machine;
5. 5. Writing to one or more ICs data from the decrypted data packet intended for the IC using the programming machine;
6. 6. After completing the writing of the IC(s): Erase the volatile memory.

The system-related object is achieved by a system for carrying out the method according to the invention, comprising a programming machine for writing to an IC and a computer machine with a volatile memory.

Advantageous embodiments emerge from the dependent claims and the description.

The core of the invention is to decrypt the data packet in preparation for writing to the IC, but the decrypted data packet to be stored exclusively in a volatile memory and made available to the programming machine from this volatile memory. This also includes storing in several volatile memories if necessary.

In order to facilitate understanding of the implementation of the method, the system in which the method according to the invention is implemented is first explained below. It is understood that the implementation of the method according to the invention is not restricted to implementation on the system described below, although this is preferred.

A programming machine is coupled to a computer machine. Preferably, this coupling is set up in such a way that the computer machine can only interact with a specific programming machine. Procedures and methods for ensuring that the computer machine can only interact with a specific programming machine are well known to those skilled in the art. The coupling between the computer machine and the programming machine increases security. Using the computer machine as a separate machine to the programming machine simplifies control over the data flow between the programming machine and the external network, since the computer machine can usually be set in a more controlled manner than the programming machine, for example because the code executed in the computer machine can be accessed more easily than in the programming machine. Existing programming machines can also be retrofitted in such a way that the method according to the invention can be carried out with them. The computer machine can be designed as a PC, for example.

The computer machine has a computing unit for executing code as well as a volatile memory, such as RAM.

The computer machine and the programming machine are preferably housed in a common housing to prevent the communication between the computer machine and the programming machine from being influenced or intercepted. Physical access to the computer machine and the physical communication lines to the programming machine is therefore not possible from the outside without opening the programming machine. The system formed in this way, consisting of the computer machine and the programming machine, is referred to below as the programming machine system.

It is also preferably provided that all external interfaces on the programming machine system, such as USB ports, drives for CDs and/or DVDs, serial interfaces, etc. are deactivated or sealed.

The programming machine system is embedded in a network and has access to external network participants, such as a server for retrieving and storing data or data packets. Preferably, only the computer machine is connected to this network; the programming machine is only connected to the computer machine. The computer machine can thus control the programming machine's access to the network, since there is no physical connection between the programming machine and the network; the computer machine is connected in between. The computer machine controls this by means of an access controller. This access controller can allow communication between the programming machine and the network bidirectionally (then the programming machine has read/write access to the network or to its participants) or unidirectionally (then the programming machine only has read access to the network or to the network participants).

The computer machine also has a state machine that is controlled by the processing unit. The state machine switches between a normal mode and a secure mode on command. The state machine switches the access controller according to the mode: in normal mode, bidirectional communication is possible, at least to relevant services and other network participants; in secure mode, only the aforementioned unidirectional communication is possible. The computer machine masks the programming machine's access to the network. Furthermore, when the state machine switches back from secure mode to normal mode, the volatile memory belonging to the computer machine is erased.

It is understood that the access controller and/or the state machine referred to here can be physically integrated into the computing unit and/or implemented in software, or the tasks of the access controller and/or the state machine can also be carried out by the computing unit.

• In einem ersten Schritt (Schritt 1) wird ein Datenpaket bereitgestellt. Das Datenpaket liegt in verschlüsselter Form vor, etwa verschlüsselt mittels einer asymmetrischen Verschlüsselung. So kann eine Entwicklungsabteilung oder ein Kunde diejenigen Daten, die auf den IC geschrieben werden sollen, von seiner Seite aus verschlüsseln. Der Betreiber der Programmiermaschine, respektive das Programmiermaschinensystem, verfügt grundsätzlich über die notwendigen Schlüssel, damit er dieses Datenpaket entschlüsseln kann.

In detail, the process according to the invention can be described - partly with reference to the system described above - as follows:

• In a first step (step 1), a data packet is provided. The data packet is in encrypted form, for example encrypted using asymmetric encryption. A development department or a customer can encrypt the data that is to be written to the IC from their side. The operator of the programming machine, or rather the programming machine system, generally has the necessary keys to be able to decrypt this data packet.

The data packet always contains the data that is intended for describing the IC. This is usually an image that is intended as a basic structure for describing the IC(s) and, if necessary, process-dependent customization data that can be used to supplement the image. In this case, the data packet can also contain information about how the process-dependent customization data should be inserted into the image.

The customization data can be provided specifically; however, it can also be generated locally using a customer application. It is also conceivable that this data is retrieved from an external server, preferably via a secure connection.

To operate a programming machine, additional configuration data is usually required that is machine-specific and may be tailored to the data intended for the IC. This machine-specific configuration data can also be part of the data package.

Other data can also be part of the data package. The data package can be in the form of an archive, for example.

In a second step (step 2), the data packet provided is loaded into the process. This is done by means of a computing unit, be it a computing unit physically assigned to the programming machine or - preferably - by means of the computing unit of the computer machine mentioned in the programming machine system described above.

The encrypted data packet can be located on a server in a network environment. To load the data packet, it is retrieved from the server.

In the third step (step 3), the loaded, encrypted data packet is decrypted. The decrypted data packet is only stored in volatile memory. Writing to non-volatile memory, such as writing to a hard disk, is not possible. This is because even if storage space is released/deleted on non-volatile memory, it is still possible for an attacker to reconstruct the previously stored data, particularly if only part of the memory is overwritten, rather than the entire memory. This is common with non-volatile memory systems.

Preferably, the volatile memory is designed as RAM, for example as part of the computer machine mentioned above. This allows decryption to be carried out locally on the computer machine; the result is then stored exclusively in the RAM.

Before step 3 or after step 3, it is preferably provided to switch the programming machine system to the secure mode already explained above in order to prevent decrypted data from being sent to the network via the programming machine.

In the fourth step (step 4), the decrypted data packet in the volatile memory is made available to the programming machine. The programming machine is thus granted access to the volatile memory.

This can be implemented, for example, by emulating a drive in the volatile memory, which is made available to the programming machine. By emulating a drive in the volatile memory, to which the programming machine is granted access, the method according to the invention can also be easily integrated into existing production lines. Programming machines usually access external drives in order to retrieve the required data packets or data in order to write to one or more ICs.

Preferably, the emulated drive is only enabled at the computer machine-side interface to the programming machine and not at the computer machine-side interface to an external network.

If the volatile memory is nevertheless integrated into a network that also includes network participants outside the programming machine system, it can be provided to secure or encrypt the emulated drive with a key known only to the programming machine, for example in the form of a password.

In a fifth step (step 5), the programming machine is used to write the data of the decrypted data packet intended for the IC(s) to one or more ICs. The writing is carried out in the usual way by the programming machine and is well known to the expert.

It is therefore preferably provided that the decrypted data packet or decrypted data extracted from it are only stored in the programming machine's volatile memory. Other measures to ensure that the decrypted data cannot be accessed from the programming machine by a third party are possible.

Depending on the programming machine, it is also possible for the data packet to consist exclusively of the data used to describe the IC; any additional configuration data can also be made available to the programming machine separately. Preferably, if the configuration data is made available to the programming machine separately, this is done in a similar way to the process described here, namely that the configuration data is also stored in encrypted form and is decrypted in a volatile memory using the method proposed here and is only made available to the programming machine from the volatile memory.

In a sixth step (step 6), after the writing of the IC(s) has been completed, the volatile memory containing the decrypted data is deleted. Deleting the data means that the data can no longer be retrieved or reconstructed from the memory by an attacker. This can be done, for example, by overwriting the entire volatile memory with different content. It can also be planned to ground the volatile memory so that it is de-energized. This is automatically the case if an attacker physically accesses the volatile memory and removes it. If the memory is removed, the power supply is interrupted, so that the contents of the volatile memory are lost.

After clearing the memory, the system is switched back to normal mode. Switching to normal mode can also include clearing the volatile memory (see above).

Usually, the data with which the IC is to be written, possibly supplemented by process-dependent customization data, is developed separately from the writing process of the programming machine in order to enable an IC to be written on different programming machine types. The machine-type-specific configuration data required to operate a programming machine type are therefore developed separately as part of a sample creation process on an individual of the respective programming machine type. To do this, the data to be written to the IC is written to the IC using the programming machine as a test and the IC is then validated to see whether the writing process has led to the desired result. If this is not the case, the configuration data is adjusted, an IC is written and validated again as a test, etc.

This pattern creation process is followed by a series production process in which a large number of identical or very similar ICs are described (the latter is the case if part of the data to be written to the IC is process-dependent customization data). It is preferably provided that during this pattern creation process, the decrypted data for writing to the IC as well as the adapted configuration data are only stored in a volatile memory and not saved in a non-volatile memory.

In detail, the pattern creation process initially provides (step A) for carrying out steps 1 to 4 described above, with the proviso that the data packet in question is the data to be written to the IC(s), i.e. the image, possibly supplemented by process-dependent customization data.

In the next step (step B), the configuration data, such as machine type-specific configuration data, are provided and, if necessary, created. This configuration data is also only stored in the volatile memory in such a way that it is made available to the programming machine. The provision can be carried out in a similar way to step 4.

A further step (step C) usually involves a functional test, after which the configuration data provided in step B is adjusted depending on the outcome. Once the configuration data has been finally provided, the configuration data and the data intended for writing to the IC are merged. This merged data is also referred to as a job. The merging can take place in an archive, for example.

In the next step (step D), the job is encrypted. This encrypted job is stored in a non-volatile memory. This can be on a server in a network environment, for example. In this way, the encrypted job can be accessed by all network participants, including other programming machine systems. If If the job is also to be accessible from other programming systems, it is necessary to encrypt the job in such a way that other programming systems can also decrypt it.

Then (step E), the volatile memory in which the decrypted data was previously stored is deleted. This can be done analogously to step 6.

It can be planned that in step D the encrypted job is not immediately saved on an external network participant, but initially only locally. Then step E is carried out (deleting the volatile memory). Only after the volatile memory has been deleted is a connection established to a network participant, such as a server, in order to save the encrypted job.

To carry out the series production process, steps 1 to 6 described above are then carried out, whereby the data package referred to therein is the job created in step C of the pattern creation process.

The pattern creation process may also provide that before the encrypted data is decrypted, the programming machine system is switched to secure mode and after step E is switched back to normal mode.

• 1: Ein schematisches Schaubild des Programmiermaschinensystems, eingebettet in ein Netzwerk.

The invention is explained in more detail using the attached figure. It shows:

• 1 : A schematic diagram of the programming machine system embedded in a network.

1 shows a programming machine system 1 embedded in a production process. In a development department 2, for example at a customer's, data is developed with which an IC 3 is to be described. This data is also referred to as an image. In addition, process-dependent customization data can be provided which modifies the image with which a specific IC 3 is to be described in detail, for example if the data is personal data. For example, process-dependent customization data can be different PIN codes to be written to the multitude of ICs. This data is transferred to a production system 4 in encrypted form. Asymmetric encryption is provided as the encryption method. The data is encrypted with the public key issued by production 4.

The encrypted data is transferred to the production system 4 and stored in the production system 4 on a server 5. For this purpose, the server 5 has non-volatile memory for securely storing the encrypted data.

In the production system 4, a large number of ICs 3 are to be written with the data developed by the development department 2 in a series production process. For this, a programming machine 6 must first be set up accordingly in a sample creation process. The setup is carried out using configuration data that is specified by a setter. To configure the programming machine 6, it is necessary to write one or more ICs 3 with the data intended for the IC 3 for test purposes, using specific configuration data to check whether the set configuration data in combination with the data intended for the IC 3 lead to the desired result. The configuration data is used to control peripherals 7 belonging to the programming machine 6, such as control devices for writing to the IC 3, for carrying out validations, etc.

In order to make the data stored on the server 5, transmitted by the development department 2, which are available on the server 5 in encrypted form, available in decrypted form to the programming machine 6 for writing to the IC 3, a computer machine 8 is part of the programming machine system 1. The computer machine 8 is coupled to the programming machine 6. The computer machine 8 is set up in such a way that it can only work with a very specific programming machine 6; connecting another programming machine 6 leads to the computer machine 8 not functioning, at least in the range of functions provided for in the method described here. The parameters and methods required for the coupling are sufficiently known to the person skilled in the art.

Communication between the computer machine 8 and the programming machine 6 is cable-based, for example via LAN. In order to prevent the exchanged data between the programming machine 6 and the computer machine 8 from being intercepted, the computer machine 8 is physically part of the programming machine system 1. This means that the computer machines 8 are housed in one and the same housing and are protected against external access.

The programming machine 6 also has access to the network outside the programming machine system 1, such as the server 5, via the computer machine 8. Access from sites of the programming machine 6 to the network outside the programming machine system 1 is, however, controlled by the computer machine 8 by means of an access controller 11. The access controller 11 is connected to a state machine 12. It is understood that the access controller 11 and the state machine 12 can also be physically part of the computing unit 9; for explanatory purposes, these are shown separately in the 1 drawn.

The state machine 12 switches the programming machine system 1 between two states: the normal mode and the secure mode.

In normal mode, the access controller 11 is set in such a way that the programming machine 6 can communicate bidirectionally with the network outside the programming machine system 1, for example with the server 5; there is thus read/write access.

If the state machine 12 receives the information from the computing unit 9 that it should switch to secure mode, the state machine 12 informs the access controller 11 that the access rights of the programming machine 6 are to be restricted so that the programming machine 6 is no longer allowed to write outside the programming machine system 1; the programming machine 6 is only granted read access to the network outside the programming machine system 1.

To retrieve the data from the server 5, they are retrieved by the computer machine 8 by means of a computing unit 9 and stored in a volatile memory 10, here a RAM of the computer machine 8.

Then the secure mode of the programming machine system 1 is switched on. The encrypted data stored in the volatile memory 10 are then decrypted by the computing unit 9.

The decrypted data is also stored exclusively in the volatile memory 10. By avoiding storing the decrypted data in a non-volatile memory, the risk is countered that an attacker can reconstruct the decrypted data, even if the data in the non-volatile memory is considered to be deleted.

The data decrypted in the volatile memory 10 are then made available to the programming machine 6. For this purpose, a drive is emulated in the volatile memory 10, which the programming machine 6 can access with its computing unit 13. Configuration data that was also previously transferred to the computer machine 8 and stored in the volatile memory 10 or in the emulated drive are also retrieved by the computing unit 13 of the programming machine 6.

Equipped with these data, the programming machine 6 writes the data intended for the IC 3 to the IC 3; the configuration data are used for the control 7 of the programming machine 6.

If the configuration data have led to the desired result (the IC 3 has been properly written), the data intended for writing the IC 3 and the configuration data, both of which are stored in the volatile memory 10 of the computer machine 8, are combined into a job, namely in an archive.

The job or archive is then encrypted and stored on the server 5 by the computer machine 8.

The computing unit 9 then sends the state machine 12 a command to switch back to normal mode. The state machine 12 then erases the volatile memory 10, for example by grounding it, and sends a command to the access controller 11 that write access for the programming machine 6 is to be permitted for the network outside the programming machine system 1. In this way, the decrypted data cannot be accessed by a third party.

Also indicated is a connection of the state machine 12 to the schematic housing of the programming machine system 1: If the housing is opened or another unexpected error occurs, the state machine 12 detects this and automatically switches to normal mode (deleting the volatile memory 10 and switching the access controller 11 to bidirectional mode.

The series production process is carried out in the same way, with the only difference being that the computer machine 8 not only retrieves the data intended for the IC 3 from the server 5, but also the entire job created in the pattern creation process. The job includes the data intended for writing the IC 3 as well as the configuration data for the controller 7 of the peripherals of the programming machine 6.

This job is - after the secure mode has been activated by the state machine 12 - stored in the volatile memory 10 in decrypted form and made available to the programming machine 6 so that the latter can write the data intended for the IC 3 using the configuration data provided.

The invention has been described using an exemplary embodiment. Without departing from the scope of protection described by the claims, numerous further embodiments for implementing the inventive concept will become apparent to those skilled in the art without these having to be explained in more detail in the context of these statements.

List of reference symbols

1

Programming machine system

2

Development department

3

IC

4

Production system

5

server

6

Programming machine

7

Control of the programming machine

8th

computer machine

9

Computing unit of the computer machine

10

Volatile, memory for computer machine

11

Access controller

12

State machine

13

Computing unit of the programming machine

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US 20070038851 A1 [0007]

Claims (9)

Method for writing data to an IC (3) with the following steps: 1. Providing a data packet in encrypted form containing the data to be written to the IC (3); 2. Loading the encrypted data packet; 3. Decrypting the encrypted data packet and storing the decrypted data packet exclusively in a volatile memory (10); 4. Providing the decrypted data packet in the volatile memory (10) for a programming machine (6); 5. Writing one or more ICs (3) with data from the decrypted data packet intended for the IC (3) using the programming machine (6); 6. After completing the writing of the one or more ICs (3): erasing the volatile memory (10). Procedure according to Claim 1 , characterized in that the encrypted data packet provided comprises, on the one hand, an image intended for writing to the IC(s) (3), optionally supplemented by process-dependent individualization data, and, on the other hand, configuration data for operating the programming machine (6) during writing. Procedure according to Claim 1 , characterized in that the volatile memory (10) is a RAM of a computer machine (8) which is coupled to the programming machine (6). Procedure according to Claim 1 , characterized in that the provision of the data in step 4 is carried out by emulating a drive in the volatile memory (10). Procedure according to Claim 1 , characterized in that the programming machine (6) is integrated into a network environment and wherein in a normal mode the programming machine (6) can write data to a network participant (read/write access) and in a secure mode writing is not possible (read-only access) and wherein at the beginning of the method according to Claim 1 Normal mode is activated, you switch to Secure mode before step 3 and switch back to Normal mode after step 6. Procedure according to Claim 1 , characterized in that for setting up a series production process, a pattern creation process is carried out in a preparatory step, comprising the following steps: A) carrying out steps 1 to 4 of the Claim 1 , wherein said data packet is the data intended for writing to the IC(s) (3); B) providing configuration data for operating the programming machine (6) in the volatile memory (10) for the programming machine (6); C) merging the configuration data and the data intended for writing to the IC(s) (3) into a job; D) encrypting the job and storing the encrypted job in a non-volatile memory; E) erasing the volatile memory (10); and wherein subsequently, to carry out the series production process, the steps of Claim 1 be carried out, whereby the data package mentioned is the job created in step C). System for carrying out the method according to one of the Claims 1 until 6 , comprising a programming machine (6) for writing to an IC (3) and a computer machine (8) with a volatile memory (10). System according to Claim 7 , characterized in that the computer machine (8) is arranged in the housing of the programming machine (6) and the computer machine (8) is arranged to erase the volatile memory (10) if the housing is unexpectedly penetrated or another unexpected behavior is detected. System according to Claim 7 or 8th , characterized in that the computer machine (8) has a first interface and a further, second interface for data exchange and wherein the computer machine (8) and the programming machine (6) are coupled to one another via the first interface and the computer machine (8) is set up so that external data which are to be made available to the programming machine (6) are retrieved by the computer machine (8) via the second interface and passed on to the programming machine (6) via the first interface and data which the programming machine (6) is to make available to external machines are passed to the computer machine (8) via the first interface and passed on to the external machine via the second interface and wherein the computer machine (8) is further set up to prevent, in a secure mode, data which the programming machine (6) wishes to make available to external machines from being passed on to the external machine.

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