WO2002095548A2

WO2002095548A2 - Method for secure loading of data in data processing units and device for implementing said method

Info

Publication number: WO2002095548A2
Application number: PCT/EP2002/005569
Authority: WO
Inventors: Michael Nolte; Richard Weigold
Original assignee: Wincor Nixdorf International Gmbh
Priority date: 2001-05-21
Filing date: 2002-05-21
Publication date: 2002-11-28
Also published as: WO2002095548A3

Abstract

The invention relates to a method and device for loading data (24) securely from a first data processing unit (10) to a second data processing unit (12). In the first data processing unit (10), a checksum (26) is formed from data (24) to be transferred and then encrypted. The encrypted checksum (32) is loaded with data (24) into a second data processing unit (12). In the second data processing unit, a second check number (38) is formed from said data (24). This second checksum is then encrypted and compared to the encrypted checksum (32) which has already been transmitted.

Description

Method for the secure loading of data in data processing systems and a device for performing the

process

The invention relates to a method for backing up data, in which data are loaded from a first data processing system into a second data processing system. Data can also be program data that are elements of a computer program. Of the data and programs to be loaded

ID, a first check digit is formed in the first data processing system. In the second data processing system, a second check digit is formed from the loaded data and programs. The two check digits are compared in the second data processing system in such a way

15 that if the result of the comparison is negative, the processing of the data or the execution of program and system steps are blocked.

The increasing networking of data processing systems and the use of publicly accessible networks for data

ÜbertragungD transmission between data processing systems make it necessary to protect the individual elements of data processing systems against unauthorized changes. All elements of the data processing system must be included in an overall security concept of the data processing system. It

Ξ5 Data and programs that are exchanged between data processing systems and data and programs that are contained in a system memory of the data processing system must be backed up. For this purpose, these data and programs undergo a test procedure for integrity control

3D and subjected to unauthorized changes. From DE 196 04 150 AI a method for confirming the receipt of a transmitted message is known. On the sender side, an integrity feature is derived from the message, which is transmitted in encrypted form to the recipient. An integrity feature is likewise formed from the message on the receiver side. The decrypted integrity feature on the transmitter side is compared with the integrity feature formed on the receiver side. The sender of the message is informed of the result of the comparison.

A method is known from patent specification DE 3705736 C2 in which data are loaded from a first data processing system into a second data processing system. A first check digit is formed from the data to be loaded in the first data processing system, which is transmitted together with the data to the second data processing system. A second check digit is formed from the loaded data in the second data processing system. The two check digits are compared with each other and if the result of the comparison is negative, the processing of the data or the execution of program and system steps are blocked. The data are each encrypted to form the check digits using a secret key using a symmetrical cryptographic algorithm. The method is used to find impermissible changes to the data and to carry out an integrity check of the data.

In data processing systems, it is also possible to load data that generally serve to ensure hardware functions. These are preferably stored on read-only memories. Such data is also called firmware. For example, it is possible to load the firmware over a network. This is another point of attack for manipulating data processing systems given. So far, no method is known that also carries out an integrity check on this data and offers reliable protection of this data against manipulation.

Furthermore, in known methods, a considerable computing effort and memory requirement of the data processing system for encrypting large amounts of data are used. The computing effort and the storage requirements for encryption depend on the amount of data to be backed up.

The object of the invention is therefore to provide a method in which the security when loading data and programs is ensured and in which a low computing power and a low storage capacity of the data processing system are used to ensure security.

15 This object is achieved for a method by the features of claim 1. Advantageous further developments are specified in the dependent claims.

In the method according to the invention, a first check digit of data to be transmitted is formed in a first data processing system, which is then encrypted according to a symmetrical cryptographic algorithm. The encrypted check digit is transmitted together with the unencrypted data to the second data processing system. In this, a second check digit is formed from the unencrypted data, which is encrypted according to the same symmetrical cryptographic algorithm as the first check digit in the first data processing system. The encrypted check digits are compared in the second data processing system. If the comparison result is negative, the processing of the data or the Execution of program and system flow steps blocked. This method ensures that manipulations are also ruled out when loading data or programs into a data processing system. Manipulations in the entire 5 program system are automatically recognized, even those that relate to data and programs that guarantee hardware functions or other basic functions.

The method also makes it possible to securely load data and programs onto a data processing system

Check ID and its integrity in this data processing system. For this purpose, only a check digit transmitted and encrypted together with the data and programs is checked for correctness. The computing effort and the memory requirement in the data processing system are

15 drive less than when encrypting and decrypting the entire data or the entire program.

In one embodiment of the invention, the first and the second check digits are formed according to the Secure HASH algorithm. The Secure HASH algorithm is a tried-and-tested zD algorithm for the generation of check digits, in which the repeated formation of check digits from a data set is highly likely to result in the same check digit. The reproducibility of the check digit is an essential prerequisite for carrying out the method according to the invention.

Ξ5 In an advantageous embodiment of the invention, the encryption of the first and the second check digit is carried out in at least one encryption unit. When the keys used for encryption are formed, the creation date of the program is preferred

3D and a device-specific character string, for example the serial number of the second data processing system, are also included. By using encryption units, manipulation possibilities during the encryption process, spying on the universal key stored in the encryption unit and the key formed from the universal key are excluded at today's discretion. The creation date of the programs and a device-specific character string are included in the formation of the secret key, which means that programs which are written on a different day than the programs from which the

10 key check digit is formed, were not accepted by the data processing system. This also ensures that programs that have been created for a specific data processing system can be encrypted using a device-specific

15 specific character string of the data processing system cannot be processed on other data processing systems. The second check digit is formed in the second data processing system according to the same algorithm and encrypted as the first check digit in the first data

Ξ0 processing plant. To create the key, the device-specific character string of the second data processing system is included, which was also included to create the key for encrypting the first check digit in the first data processing system. In front-

Ξ5 this device-specific character string is preferably on a chip card, e.g. on a SIM card, stored in the second data processing system.

In a further advantageous embodiment of the invention, the DES (Data Encryption Standard) algorithm is used to encrypt the first and the second 3D check digit. The check digits are preferably encrypted three times according to the DES algorithm in the CBC (chiper block chain) encryption method. This will it is sufficient that the check digits are encrypted according to a method that is considered secure and that it is not possible to spy on the key used to manipulate the data. The amount of data of the check digits formed can be predetermined and is usually in the range from one byte to 50 bytes. However, the amount of data can be chosen to be as large as required to increase security. An increase in the amount of data requires a corresponding computing power of the data processing system in order to be able to carry out the encryption in a reasonable time. The check digit preferably comprises a data volume of 20 bytes. This provides a high level of security for the currently customary computing power, the computing effort being limited to an acceptable level.

According to a further aspect of the invention, a device with the features according to claim 12 is specified. Such a device allows encrypted check digits to be used to check data or programs as to whether they have been manipulated between being created in a first data processing system and being loaded into a second data processing system.

In a further embodiment of the invention, the second data processing system is a controller, for example a controller with a microcontroller, the transmitted data including the firmware of the controller or the firmware for its hardware components. The result of this is that the method can be used in a variety of ways and that it is possible to protect data from control systems against manipulation. Further features and advantages of the invention will become apparent from the following description, which in connection with the accompanying drawings explains the invention using an exemplary embodiment.

5 It shows:

1 shows an overview of the systems involved in the data transmission,

2 shows the basic structure of the development system for creating and encrypting a first ID check digit, and

Fig. 3 shows the basic structure of the target system for creating and encrypting a second check digit and for comparing the two encrypted check digits.

FIG. 1 shows an overview of the systems involved in the data transmission. Firmware for a target system 12, for example for a central payment controller of an automated teller machine, is transmitted in the form of data 14 on a development system 10. Line 20 marks the ΞD separation between the development system 10 and the target system 12 of the firmware. An encryption unit 16, 18, which is also referred to as a cryptographic unit, is arranged in the development system 10 and in the target system 12. These encryption units 16, 18 Ξ5 generally form an inseparable unit with an input unit, for example with a keyboard. The keyboard cannot be separated from the encryption unit 16, 18 without destroying the keys and data stored in the encryption unit 16, 18. When operating the Geld-SD automat, this arrangement ensures that secret data such as the personal identification number (PIN) of the Operator can not be spied on. This also prevents manipulation of the encryption unit 16, 18 or the keyboard. Such an encryption unit 16, 18 with an input unit in the development system 10 is, for example, a master pin pad from Krone. The encryption unit 18 with input unit used in the target system 12 is also referred to as an encrypted pin pad.

FIG. 2 shows a basic structure of the development system.

10 stems 10 shown for creating and encrypting a first check digit. The same elements have the same reference symbols. The development system 10 has a computing unit 22, e.g. a personal computer, and a cryptographic unit 16, e.g. a master pin pad. The firmware created

15 is present as net binary data 24 in the computing unit 22. A check digit 26, which is also referred to as HASH, is formed from these net binary data 24 according to a secure hash algorithm. The secure hash algorithm forms a check digit 26. This check digit 26 and a create

LDate 28 of the firmware is transferred to the cryptographic unit 16. This creates, among other things, the creation date 28 of the firmware and a device-specific character string of the target system 12, e.g. a serial number, a secret key 30 and thus encrypts the

Ξ5 check digit 26 according to a symmetrical cryptographic algorithm to an encrypted check digit 32. In this exemplary embodiment, the check digit 26 is encrypted three times by means of the DES algorithm in the CBC encryption method.

30 The net binary data 24, the encrypted check digit 32 and the creation date 28 of the firmware are combined in a firmware file 34. The firmware file 34 will transmitted as a data set 14 to a computing unit 36 of the target system 12.

In Figure 3, the basic construction of the target system 12 is shown for creating and encrypting a second ^'check digit 42 5 as well as to compare the two encrypted check digits 32, 42nd The computing unit 36 of the target system 12 is located in a mechanically secured area of the target system 12, for example in the safe of the ATM. The encryption unit 18 of the line system 12, the encrypted pin pad, is not arranged in the secured area. The input unit of the Encrypted Pin Pad is arranged in the target system so that it is freely accessible by the operator.

After the firmware file 34 has been transmitted as data 14 to the computing unit 36 of the target system 12,

15 the net binary data 24 of the firmware, a second check digit 38 is formed according to the same symmetrical cryptographic algorithm as the first check digit 26 in the computing unit 22 of the development system 10. The creation date 28 of the firmware and the second check digit formed

ΞD 38 are transferred to the cryptographic unit 18. This creates from the firmware date 28 and one on a storage medium, e.g. a chip card, device-specific character string of the target system 12 stored in the target system 12, e.g. -the serial number, a secret key 40. With

With the aid of the secret key 40, the second check digit 38 is encrypted to form the second encrypted check digit 42 and fed to a comparison unit 44. The first encrypted check digit 32 transmitted together with the firmware file 34 is also assigned to the comparison unit 44.

30 leads.

In a further embodiment variant, the secret key 30, which is in the unlocking system 10, differs was formed by the secret key 40 formed in the target system 12. As a result, it is necessary to re-encrypt the check digit 32 encrypted in the development system 10 in the encrypted pin pad 18 of the target system 12 before the comparison. The U key ensures that the check digit 32 encrypted in the development system 10 is comparable to the check digit 42 generated and encrypted in the target system 12.

If the comparison result 46 is positive, the net binary data 24 of the firmware are released for processing. In the event of a negative comparison result 48, the processing of the net binary data 24 of the firmware is prevented and a corresponding error signaling takes place on a display unit (not shown).

Reference number list development system target system transmitted data (firmware file) encryption unit encryption unit transfer between development and target system computing unit net binary data (firmware) formation of the first check digit creation date of the firmware secret key for encryption encrypted first check digit firmware file for transmission to the target system computing unit formation of the second check digit secret key for encryption, encrypted second check digit comparison of release and processing firmware no release firmware

Claims

claims

1. A method for backing up data, in which data (24) are loaded from a first data processing system (10) into a second data processing system 5 (12), a first check digit from the data (24) to be loaded in the first data processing system (10) (26) is formed, a second check digit (38) is formed from the loaded data (24) in the second data processing system (12), a comparison of the two check digits (26, 38) is carried out, and in which one negative comparison result that the 15 processing of the data (24) or the execution of program and system steps is blocked, so that indicates that the first check digit (26) in the first data processing system (10) after a symmetrical cryptographic SD Algorithm is encrypted so that the encrypted check digit (32) together with the unencrypted data (24) is transmitted to the second data processing system (12) that the second check digit (38) is encrypted in the second data processing system (12) according to the same symmetrical cryptographic algorithm as the check digit (26) in the first data processing system (10), and that the encrypted check digits (32, 42) are compared in the second data processing system (12).

5 2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the first and the second check digit (26, 38) are formed according to the Secure HASH algorithm.

3. The method according to claim 1 or 2, so that the encryption of the first and second check digits (26, 38) is carried out in at least one encryption unit (16, 18).

15

4. The method according to any one of claims 1 to 3, characterized in that in the second data processing system, the check digit formed is encrypted with a secret Ξ0 key, which differs from the secret key in the first data processing system, and that the encrypted by the first data processing system Check digit is converted in the second data processing system.

Ξ5

5. The method as claimed in one of claims 1 to 4, such that the DES algorithm is used to encrypt the first and second check digits (26, 38),

30 in particular that the check digits (26, 38) are triple be encrypted according to the DES algorithm in the CBC encryption process.

6. The method according to any one of claims 1 to 5, since - 5 characterized in that in the keys (38, 40), which serve to encrypt the check digits (26, 38), also the creation date (28) of the data (24) with is included.

7. The method as claimed in one of claims 1 to 6, that the data transmitted is a firmware of the second data processing system and / or the firmware of hardware components of the second data processing application.

15 layers included.

8. The method according to any one of claims 1 to 7, characterized in that in the second data processing system (12) Ξ0 is a storage medium on which data are stored with which the key (30) for encrypting the first check digit (26) in the first data processing system (10) was formed, and that this data is used to encrypt the second check digit (38) in the second data processing system (12).

9. The method according to claim 8, d a d u r c h g e k e n n z e i c h n e t,

30 that the storage medium is a chip card.

10. The method according to any one of claims 1 to 9, that the check digit (26, 38) has a size between 1 byte and 50 bytes, in particular that it is 20 bytes in size.

5

11. The method according to any one of the preceding claims, characterized in that the second data processing system is a controller.

10 12. Device for backing up data, in which data (24) is loaded from a first data processing system (10) into a second data processing system (12), from the data (24) to be loaded in the first data processing system (10) a first check digit (26) is formed, a second check digit (38) is formed from the loaded data (24) in the second data processing system (12),

Ξ0 and in which a comparison of the two check digits (26, 38) is carried out, and in which if the result of the comparison is negative, the processing of the data (24) or the execution of program and system steps are blocked,

Ξ5 indicates that the first check digit (26) in the first data processing system (10) is encrypted according to a symmetrical cryptographic algorithm, that the encrypted check digit (32) together with the 30 unencrypted data (24) for the second Data processing system (12) is transmitted, that the second check digit (38) in the second data processing system (12) is encrypted according to the same symmetrical cryptographic algorithm as the check digit (26) in the first data processing system (10), and that the encrypted check digits (32, 42) in the second data processing system (12) can be compared.

10 13. A device according to claim 12, characterized in that the second data processing system is a controller.

14. Device according to one of claims 12 or 13, d a - 15 by g e ke nn z e i chne t that the transmitted data include firmware of the second data processing system and / or the firmware of hardware components of the second data processing system.

15. Device according to one of claims 12 to 14, since - Ξ0 characterized in that in the second data processing system (12) there is a storage medium on which data are stored with which the key (30) for encrypting the first check digit (26) was formed in the first data processing system and that these data are used to encrypt the second check digit in the second data processing system.

16. The device according to claim 15, dadurchge - 30 indicates that the storage medium is a chip card.

7. The method according to any one of claims 12 to 16, so that the check digit (26, 38) has a size between 1 byte and 50 bytes, in particular that it is 20 bytes in size.