Meteosat Second Generation Interface Control Document Station Key Unit

Transcription

1 Issue: 11 Interface Control Document Station Key Unit

2 Document Signature Table Issue: 11 Document Signature Table Name Function Signature Date Prepared by Niklas Sinander Telecommunications Engineer Checked by Ernst Schaffner MSG Ground Segment Facilities Procurement Manager Checked by Andrew MacTavish QA Engineer Approved by Ernst Schaffner MSG Ground Segment Facilities Procurement Manager i

3 Document Change Record Issue: 11 Document Change Record Issue/Revision Date DCN No Changed Pages/Paragraphs 10 Draft 28/09/00 Draft Release 10 01/11/00 Initial Release 11 11/10/02 Implementation of Corrigendum EUM/MSG/TEN/567 (Replacement of Section 33 Hardware Interface ) ii

4 Distribution List Issue: 11 Distribution List Name Internal Distribution No Copies 1 External Distribution Company Name No Copies Vendor 1 iii

5 Table of Contents Issue: 11 Table of Contents 1 INTRODUCTION 1 11 PURPOSE AND SCOPE OF THE INTERFACE CONTROL DOCUMENT 1 12 DOCUMENT STRUCTURE 1 13 APPLICABLE AND REFERENCE DOCUMENTS Applicable Documents Reference Documents 1 14 OPEN ISSUES AND ASSUMPTIONS 1 2 SKU PROGRAMMING INTERFACE 2 21 PURPOSE 2 3 SKU USER STATION INTERFACE 3 31 PURPOSE OF THE INTERFACE 3 32 PROTOCOL Overview Relationship to DES Bit Notation Definition Method of Use Command Set 5 33 HARDWARE INTERFACE Standards Specifications 13 4 GLOSSARY15 iv

6 List of Tables Issue: 11 List of Tables Table 1: SKU Command and Result String Principles4 Table 2: Result Byte Definition 4 Table 3: Write PBK Command 5 Table 4: Write PBK Response 6 Table 5: Read PBK Command6 Table 6: Read PBK Response 7 Table 7: Calculate PNK Command 8 Table 8: Calculate PNK Response8 Table 9: Self-Test Command9 Table 10: Self-Test Response9 Table 11: Inquiry Command 10 Table 12: Inquiry Response 11 Table 13: Error Response12 Table 14: Busy Response 12 Table 15: Power Supply13 Table 16: Data Interface Specification (1)13 Table 17: Data Interface Specification (2)14 Table 18: Data Interface Specification (3)14 v

7 Introduction Issue: 11 1 Introduction 11 Purpose and Scope of the Interface Control Document The purpose of the is to define all aspects of the different interfaces of the SKU This ICD provides the specification of the SKU programming interface and of the interface between the SKU and the User Station 12 Document Structure This document is divided into three main sections Section 1: is an overview defining relations and the context for the rest of the document Section 2: defines the interface for programming the SKU with the secret Master Keys (MSK) Section 3 defines the interface for interaction with the User Station and SKU Testing environments 13 Applicable and Reference Documents 131 Applicable Documents AD1 LRIT/HRIT Mission Specific Implementation, EUM/MSG/SPE/ Reference Documents - None 14 Open Issues and Assumptions - None 1

8 SKU Programming Interface Issue: 11 2 SKU Programming Interface 21 Purpose The purpose of the SKU Programming Interface is to provide a means to program the SKU with a secret Master Key The KCE will generate a MSK according to certain criteria and store it in a file A programming tool will read the file and use the information contained therein to program the SKU The SKU programming tool which is a part of the MSG DADF facility shall be used Thus the interface between the KCE and the programming tool will not be redefined in this document The interface between the programming tool and the SKU is highly dependant of the implementation of the SKU Thus this interface will not be described in detail 2

9 Issue: Purpose of the Interface The purpose of the SKU User Station interface is to provide a direct hardware and software connection to the User Station and also to the SKU Testing Environment The interface will serve two purposes; - to provide the User Station with a Pseudo Noise Key which the User Station will use to decrypt data streams received from the MSG satellites - to test and verify the functionality of the SKU 32 Protocol 321 Overview This chapter describes the basic principles of the protocol Only a small number of instructions to the SKU and a small number of responses from the SKU are necessary to provide the entirely required SKU functionality For naming convention it should be pointed out, that: The bits in one byte (8 bits) are numbered according to their binary weight, that means bit 0 is the least significant bit and bit 7 is the most significant bit A designates the ASCII representation of the related bit pattern (A =ˆ ) <CR> designates an ASCII control code, here carriage return ( <CR> =ˆ ) 322 Relationship to DES Bit Notation The keys which are used in the SKU for decryption purposes are so-called DES3 keys, which are composed by a concatenation of three single DES keys The keys are numbered Key(1), Key(2) and Key(3) from left to right, conformant to the LRIT/HRIT Mission Specific Implementation, [AD1] Each single DES key contains 64 bits, numbered also from left to right It should be mentioned that each 8th bit is a parity bit for the predecessor bits Following this numbering convention the first bit of the first single DES key K(1,1) is the most left one and is referred to be the most significant bit (MSB), which is transferred first in a data stream All DES key containing data stream transfers from or to the SKU are based on the above given explanations 323 Definition The data passing the SKU interface can be identified as instructions to the SKU and answers from the SKU Basic to all the data streams is the fact that they all share the same structure This principle command structure for an instruction to the SKU is shown in the following table Each command to the SKU begins with a as a start symbol, which can be used for synchronisation purposes After that three bytes are provided to specify the command These identifiers are followed by a separator All these five bytes are ASCII coded and together form the so-called header of the command Afterwards the data are transferred, for example a key number, a public key and a public key CRC field etc Each information byte will be coded in two digit hexadecimal numbers Because of this only the codes 0 9 and A F can occur in data fields Leading zeros must neither be substituted by any other code nor be omitted The sequence of digits is always starting with the most significant digit and ending with the least significant digit The hexadecimal digits again are ASCII coded for the transmission 3

10 Issue: 11 The SKU command always ends with <CR> as a delimiter Byte-No Contents Function 0 start symbol 1 X 2 Y 3 Z 5 0 F MSD 6 0 F LSD 7 0 F MSD n-2 0 F LSD n-1 <CR> stop symbol Table 1: SKU Command and Result String Principles The response string from the SKU is described by the same data structure In addition a so-called result byte is inserted prior to the <CR> delimiter The result byte is represented as two ASCII coded hex digits The result byte gives information about errors that occurred during execution of a previous received instruction The result byte s construction is chosen in a way, that errors for all implemented SKU commands are coded by the eight bits of the byte Therefore the same result byte can be used in all SKU response strings The type of error is coded by the binary weight of the corresponding bit The meaning of each individual bit within the result byte is shown in the following table Result Byte Description MSD bit 3 = 1: time out error detected 0: OK LSD Table 2: Result Byte Definition bit 2 = bit 1 = bit 0 = bit 3 = bit 2 = bit 1 = bit 0 = 1: data error detected 0: OK 1: unknown command detected 0: OK 1: MSG parity error at PNK calculate access 0: MSG parity OK at PNK calculate access 1: PBK CRC error at PNK calculate access 0: PBK CRC OK at PNK calculate access 1: CRC error at PBK read access 0: CRC OK at PBK read access 1: CRC error before PBK write access 0: CRC OK before PBK write access 1: CRC error after PBK write access 0: CRC OK after PBK write access 4

11 Issue: 11 Due to this command structure and coding principle it is possible to detect transmission errors caused for example by electromagnetic interference For this reason the SKU reacts with answers including a detailed result byte to all received instructions or instruction fragments even though they are detected to contain corrupted data 324 Method of Use The basic scheme of the communication protocol can be described as follows: The User Station sends an instruction to the SKU and the SKU reacts by outputting an appropriate answer The synchronisation of incoming commands is performed with the help of the leading of each instruction, as already mentioned above If the SKU detects any instruction error, corrupted data our time out situations, a so-called error message will be returned 325 Command Set 3251 Write PBK The Write PBK command is used to initiate a storage procedure for a public key in the SKU s non volatile memory The instruction is directed from the User Station to the SKU A detailed description of the command structure is given in the table below Byte-No Contents Function 0 start symbol 1 W 2 R 3 I 5 0 F MSD 6 0 F LSD key number (ASCII coded hex) 7 0 F MSD 8 0 F 54 0 F LSD 55 0 F MSD 56 0 F 57 0 F 58 0 F LSD public key (ASCII coded hex) CRC field (ASCII coded hex) Table 3: Write PBK Command 59 <CR> stop symbol 5

12 Issue: 11 The command contains the key number, the public key and the public key CRC field in ASCII coded hexadecimal digits The complete command consists of 60 bytes After performing a correct received Write PBK command the SKU response is as follows Byte-No Contents Function 0 start symbol 1 W 2 R 3 I Table 4: Write PBK Response 5 0 F MSD 6 0 F LSD key number (ASCII coded hex) 7 0 F MSD 8 0 F LSD result (ASCII coded hex) 9 <CR> stop symbol The message contains the key number and the result byte, both as ASCII coded hexadecimal digits If the SKU detects a CRC error in the received public key, the write access will be rejected, and the PBK will be set to Read PBK The Read PBK command is used to read out a public key from the SKU s non-volatile memory The instruction is directed to the SKU A detailed description of the command structure is given in the table below Byte-No Contents Function 0 start symbol 1 R 2 D 3 P Table 5: Read PBK Command 5 0 F MSD 6 0 F LSD key number (ASCII coded hex) 7 <CR> stop symbol 6

13 Issue: 11 The command contains the key number for the desired public key in ASCII coded hexadecimal digits The complete command consists of 8 bytes After the execution of a correctly received Read PBK command the SKU returns the following Byte-No Contents Function 0 start symbol 1 R 2 D 3 P 5 0 F MSD 6 0 F LSD key number (ASCII coded hex) 7 0 F MSD 8 0 F 54 0 F LSD 55 0 F MSD 56 0 F 57 0 F 58 0 F LSD public key (ASCII coded hex) CRC field (ASCII coded hex) Table 6: Read PBK Response 59 0 F MSD 60 0 F LSD result (ASCII coded hex) 61 <CR> stop symbol The message contains the key number, the public key, the public key CRC field and the result byte, all as ASCII coded hexadecimal digits The result byte gives information about CRC errors, occurred during execution of a Read PBK instruction The complete message consists of 62 bytes 3253 Calculate PNK The Calculate PNK command is used to initiate a pseudo noise key generation procedure in the SKU The instruction is directed to the SKU A detailed description of the command structure is given in the table below 7

14 Issue: 11 Byte-No Contents Function 0 start symbol 1 C 2 A 3 L 5 0 F MSD 6 0 F LSD 7 0 F MSD 8 0 F Table 7: Calculate PNK Command 22 0 F LSD 23 <CR> stop symbol key number (ASCII coded hex) seed (ASCII coded hex) The command contains the key number and the seed in ASCII coded hexadecimal digits The complete command consists of 24 bytes The next table illustrates the SKU result, transmitted via the serial interface Byte-No Contents Function 0 start symbol 1 C 2 A 3 L 5 0 F MSD 6 0 F 52 0 F LSD pseudo noise key (ASCII coded hex) Table 8: Calculate PNK Response 53 0 F MSD 54 0 F LSD result (ASCII coded hex) 55 <CR> stop symbol 8

15 Issue: 11 The message contains the pseudo noise key and the result byte, both as ASCII coded hexadecimal digits The result byte gives information about CRC errors and MGK parity check errors, occurred during execution of a Calculate PNK instruction It should be pointed out that all PNK digits will be set to zero by the SKU, if an error has been detected during the PNK computation process The complete message consists of 56 bytes The necessary time to transmit the response values via the serial link has to be taken into account for performance aspects 3254 Perform Self-Test The Perform Self-Test command is used to cause a SKU self-test procedure The instruction is directed to the SKU A detailed description of the command structure is given in the table below Byte-No Contents Function 0 start symbol 1 T 2 S 3 T Table 9: Self-Test Command 5 <CR> stop symbol The command does not contain any special data The SKU will not automatically output the self-test results after the checking sequence For this reason a special command is foreseen to read out the internal status of the SKU After a power or reset the SKU executes also a self-test and stores the results in it s internal RAM These results can be requested with the help of the above mentioned special command The Perform Self-Test instruction can be used, if an additional self-test during operation is required The complete command consists of 6 bytes After execution of a correctly received Perform Self-Test command the SKU replies the following data frame as an acknowledgement Byte-No Contents Function 0 start symbol 1 T 2 S 3 T Table 10: Self-Test Response 5 0 F MSD 6 0 F LSD result (ASCII coded hex) 7 <CR> stop symbol 9

16 Issue: Inquiry SKU Status The Inquiry SKU Status command is used to read out the SKU status and the self-test results This includes the firmware revision number, the hardware revision number and station number The instruction is directed to the SKU A detailed description of the command structure is given in the table below Byte-No Contents Function 0 start symbol 1 I 2 S 3 S Table 11: Inquiry Command 5 <CR> stop symbol The SKU return string is shown in the next table 10

17 Issue: 11 Byte-No Contents Function 0 start symbol 1 I 2 S 3 S 5 0 F MSD 6 0 F LSD firmware revision number (ASCII coded hex) 7 0 F MSD 8 0 F LSD hardware revision number (ASCII coded hex) 9 0 F MSD 10 0 F 11 0 F 12 0 F LSD 13 0 F MSD 14 0 F 15 0 F 16 0 F LSD SKU station number (ASCII coded hex) check sum of internal ROM (ASCII coded hex) 17 0 F MSD 18 0 F LSD status MSD LSD : : all bit 3 bit 2 bit 1 bit 0 : : : : : set to 0 set to 0 1 = external EEPROM error 0 = external EEPROM OK 1 = external RAM error 0 = external RAM OK 1 = internal RAM error 0 = internal RAM OK 19 0 F MSD 20 0 F LSD result (ASCII coded hex) 21 <CR> stop symbol Table 12: Inquiry Response The message contains the hardware revision number, firmware revision number and station number Also the check sum of the internal ROM, a status byte and the result byte are included All bytes are represented in ASCII coded hexadecimal digits The status byte provides detailed information about the SKU s memory status 11

18 Issue: Error Response The SKU message Error will be transmitted by the SKU, if the SKU has detected a transmission error or corrupted data A detailed description of the message structure is given in the table below Table 13: Error Response Byte-No Contents Function 0 start symbol 1 E 2 R 3 R 5 0 F MSD 6 0 F LSD result (ASCII coded hex) 7 <CR> stop symbol The message contains only the result byte in ASCII coded hexadecimal digits 3257 Busy Response The SKU message Busy will be returned by the SKU, if a <CR> delimiter is detected at the input stage during software initiated self-test period All other characters reaching the SKU input during a self-test will be discarded Table 14: Busy Response Byte-No Contents Function 0 start symbol 1 B 2 S 3 Y 5 0 F MSD 6 0 F LSD result (ASCII coded hex) 7 <CR> stop symbol 12

19 Issue: Hardware Interface 331 Standards The SKU interface provides a full duplex serial interconnection compliant to the TIA/EIA RS-422 standard The related data interface specifications are provided in the following tables For completeness, the description of the power supply interface is supplied, too 332 Specifications Parameter Value Connector three pole earth-connected IEC 320 Voltage V AC ~ Frequency Hz [TBC] Power Consumption 5 W Input Surge Current 8 A (110V) / 16 A (230V) Fuse 05 A time-lag blow-out fuse 5 x 20 mm Table 15: Power Supply Parameter Type full duplex Standard TIA/EIA RS-422 Connector 9 pole SubD Baud Rate bits/s Start Bits 1 Data Bits 8 Stop Bits 1 Parity No Value Table 16: Data Interface Specification (1) 13

20 Issue: 11 TxD+ TxD- RxD+ RxD- Signal Description non inverting transmit output inverting transmit output non inverting receiver input inverting receiver input Table 17: Data Interface Specification (2) Signal Pin Pin Signal GND 1 6 Not Connected TxD+ 2 7 TxD- Not Connected V ± 5% max 200 ma RxD+ 4 9 RxD- Not Connected 5 Table 18: Data Interface Specification (3) 14

21 Glossary Issue: 11 4 Glossary CRC DADF DES ICD KCE LSD MSD MGK MSK PBK PN SKU Cyclic Redundancy Check Data Acquisition and Dissemination Facility Data Encryption Standard Interface Control Document Key Centre Element Least Significant Digit Most Significant Digit Message Key Master Key Public Key Pseudo Noise Station Key Unit 15