Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
  • G06F21/60—Protecting data
  • G06F21/64—Protecting data integrity, e.g. using checksums, certificates or signatures
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/06—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols the encryption apparatus using shift registers or memories for block-wise or stream coding, e.g. DES systems or RC4; Hash functions; Pseudorandom sequence generators
  • H04L9/0643—Hash functions, e.g. MD5, SHA, HMAC or f9 MAC
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
  • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
  • Y04S40/00—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them
  • Y04S40/20—Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Definitions

• the present invention relates to an apparatus and a method for checking a data volume by means of test values and to a device and a method for determining a comparison test value for a data volume, which may be, for example, a computer file.
• the amount of data is very large, even if the data is in kompri ⁇ mated form.
• a typical MP3 coded song generates a data volume of 1 MB per minute of playing time.
• hash algorithm In order to check the integrity of a file, for example by means of a hash algorithm, the hash algorithm is usually calculated over the entire file and then the result, ie the hash value, is compared with a reference value. Such an integrity check of a data record by a cryptographic hash method is described below.
• Cryptographic hash values are also called test surranes.
• Hash methods calculate from an input of indeterminate length defined and clearly a specific output value, the so-called hash. For example, the hash value is a 20-byte string.
• the type of hash function is to specify a unique output value for any input value from which the input value can not be recalculated.
• the complete amount of data to be used to calculate the hash value is first processed using the hash algorithm, so that the hash of the data set is formed. For later integrity checks, the data set to be tested is completely reworked using the hash algorithm. If the data quantity to be tested supplies the same hash as in the reference run, it may be assumed that no changes were made to the data set.
• the main task of hash functions is to check and ensure the integrity of digital data.
• the application cases range from checksum calculations to signature procedures. That is, the hash is either used directly as a checksum or in addition, signed representative of the original amount of data. For integrity checking, the direct use of the hash value is used as the checksum.
• hash functions can essentially be defined by the following three points. On the one hand, every hash value must occur the same number of times. This means that the probability of hash values must not differ for different input values. Furthermore, small changes in the input value should lead to a changed hash value. Furthermore, the effort to generate collisions should be very high. This means that It should be as difficult as possible to find a second input value with the same hash value for a given input value.
• a hash function fulfilling all three requirements is called a cryptographic hash function.
• SHA-I Secure Hash Algorithm
• MD4 MD5
• SHA-I five 32-bit variables, so-called chain variables and the so-called compression function play an important role.
• the hash function SHA-I first divides the input value into 512-bit blocks.
• the compression function then picks up the five chain variables and a five 512-bit block and maps them to the next five 32-bit values.
• the function now runs in four rounds for every 20 identical operations in which the individual bits are shifted according to predefined arithmetic operations. Finally, the contents of the five chain variables are output as a hash value.
• hash integrity checking techniques Use of hash integrity checking techniques is described, for example, in the specification "Open Mobile Aliance; OMA DRM Specification V2.0; Draft Version 2.0 - ' 10th April 2004. Further test methods are described, for example, in the specification "Internet Streaming Media Alliance, Encryption and Authentication Specification, Version 1.0, February 2004".
• the integrity check of a dataset is not an end in itself. Rather, the integrity check is only preceded by the actual use of the data record. The effort for the integrity check is therefore disadvantageous when using a data set since the integration an additional expenditure, which causes additional costs and delays the use of the data set.
• the high level of effort involved is of particular importance because it is always the entire data set that has to be checked before it can be said whether the integrity of the data record is given. This has an especially noticeable effect on very large data sets and can, for example, lead to start delays in the playback of audio data or video data in the case of audio and video files.
• Another major disadvantage is due to the high energy consumption, which arises from the necessity that always first the entire data set must be checked. This is necessary even if only part of the data is to be used. For example, even with a brief start or fast forward or rewinding of a DRM-protected audio piece or video piece on a portable playback device, a check of the entire audio piece or video piece is first required. In portable devices in particular, this results in a shortening of the battery life.
• a device for checking a data quantity according to claim 1 a device for determining a test value according to claim 10
• a method for checking a data amount according to claim 15 a method for determining a test value according to claim 16 and a computer program solved according to claim 17.
• the present invention provides a device for checking a dataset, wherein the dataset has a plurality of subsets and a sub-test value per subset, with the following features:
• a device for determining a test value which is designed to determine a common test value from the provided partial test values of the subsets;
• comparison device which is designed to compare the common test value with a comparison test value provided to the comparison device.
• the present invention further provides a device for determining a comparison test value from a data quantity which has a plurality of subsets, with the following characteristics:
• the present invention is based on the finding that a partial or partial integrity check of a data record results in a reduction of the effort required for the integrity check or for the generation of the test value.
• test values are formed over subsets of the data record.
• the test values of these subsets are stored either in the data record or separately.
• an additional test value is formed over the partial test values. This is advantageous because, to verify the integrity of the data set, the partial test values may first be tested against the additional test values. Subsequently, the individual subareas can be checked with the aid of the checksums assigned to the individual subareas.
• the possibility of checking the integrity in sections results in a number of advantages.
• the use of data can already take place if only the first section of the data record and not the entire data record has yet been checked. For example, can begin ei ⁇ nes audio / video piece with virtually no time lag 'be ⁇ so playback.
• a data set can optionally also be used only partially without the entire data set having to be checked. For example, when fast-forwarding and rewinding within an audio / video piece or jumping within the piece, a section-wise review is advantageous. The section-by-section check eliminates the need to check sections that are not required. This saves time and resources.
• the actual use of the data can be carried out in sections in parallel with the integrity check.
• a piece of data only needs to be loaded once from a disk to first check the integrity of the piece and then process it immediately. This leads to time, resource and energy savings.
• the check can also be downstream. This is possible if it is acceptable that individual pieces of the file can already be used without verification. In this case, for example, the first piece or another piece of a music file is used and tested parallel to that of use. This has the advantage that the data to be checked during the execution are checked. Furthermore, the data to be used only needs to be fetched once from the hard disk. If the check is successful, the next piece is released for processing. Otherwise, the processing stops after the currently running piece.
• the approach according to the invention makes it possible to quickly pre-check a data record by pre-checking the test values of the sub-sections of a data record. This allows, for example, a quick overview of a large number of data records. The actual verification of the data records themselves by means of the test values then takes place only after the test values have been checked.
• further intermediate test values can be formed from the partial test values of the individual subsets. From the intermediate test values, the number of which is smaller than the number of partial test values, a common test value is again formed.
• the DCF format is in "Open Mobile Alliance; DRM Content Format V2.0; Draft Verison 2.0 - 20 April 2004 "and is used for encrypted audio / video data in the MPEG-4 data format.
• FIG. 1 is a block diagram of an apparatus for checking a data amount according to an embodiment of the present invention.
• FIG. 2 shows a block diagram of a device for determining a test value according to a further exemplary embodiment of the present invention.
• FIG. 1 shows a schematic representation of a device for checking a data volume, which has a device 102 for determining a test value, a comparison device 103 and a device 104 for using the data volume.
• the device for checking a data amount is designed to check the amount of data before use by means of partial test values and a comparison test value.
• the part check values and the comparison check value are provided to the device for checking a data amount along with the data amount.
• the device 102 for determining a test value is formed to receive a data amount 112.
• the data set 112 is subdivided into a plurality of subsets (not shown in the figures). For each of the subsets of the data set 112, a partial check value 114 was calculated.
• the partial test values 114 are also provided to the device 102 for determining a test value.
• a comparison check value 118 was formed from the partial check values 114, which is also provided to the device for checking a data volume.
• the partial test values 114 and the comparative test value 118 were determined, for example, in the apparatus shown in FIG. 2 for determining a test value from the data quantity and buffer-stored together with the data quantity.
• the device 102 for determining a test value is designed to calculate a common test value 116 from the partial test values 114 and to provide it to the comparator 103.
• the comparison device 103 is also designed to receive a comparison test value 118.
• the comparison check value 118 was also formed from the partial check values 114. The same calculation function was used to form the comparison test value 118 and the common test value 116.
• the comparison device 103 is designed to compare the common test value 116 with the comparison test value 118. According to this exemplary embodiment, the comparison device 103 is designed to provide a comparison signal 120 to the device 102 for determining a test value depending on the comparison result between the common test value 116 and the comparison test value 118.
• the comparison signal 120 indicates whether the comparison test value 118 coincides with the common test value 116. If the common test value 116 and the comparison test value 118 agree, it can be assumed that the partial test values 114 from which the common test value 116 was formed have not changed since the comparison test value 118 was formed.
• the device 102 for determining a test value is designed to calculate a first further partial test value 122 from a first subset of the data quantity 112 in the case of a comparison signal 120 indicating a match of the comparison value 118 and the common test value 116 and to the comparator 103.
• the comparison device 103 is likewise designed to receive the partial test values 114.
• the comparison device 103 is designed to compare the further partial test value 122 with the corresponding partial test value 114, which was formed from the same subset as the further partial test value 122.
• the comparison device 103 is designed to provide a test result 124 to the device for using the data volume.
• the test result 124 indicates whether the partial test value 114 matches or does not match the associated further partial test value 122.
• the further partial test value 122 was formed from the associated subset according to the same algorithm as the partial test value 114. Thus, if the partial test value 114 matches the further partial test value 122, it can be assumed that the partial data quantity is the further partial test value 122 has been calculated since the calculation of the associated partial test value 114 has not been changed.
• the means 104 for using the amount of data is designed to be used in a test result 124 which has a conformity Mood of the sub-test value 114 with the further sub-test value 122 indicates to use the subset of the data set 112 for which the further sub-test value 122 has been formed and compared in the comparison device 103.
• the device 102 may be designed to determine a test value in order to determine the further partial test values 122 of the subset of the data amount 112 in parallel as a consequence of the comparison signal 120 and to provide them to the comparison device 103. Furthermore, the device 102 may be designed to determine a test value in order to already generate the further partial test values 122 before the common test value 116 has been compared with the comparison testers 118.
• the partial test values 114 can be provided separately to the data set 112 to the device 102 for determining a test value. Alternatively, the partial test values 114 may be integrated in the data set 112. Likewise, the compare check value 118 may be provided along with the dataset 112 to the device for checking a dataset.
• the device 102 can be designed to determine a test value. to already form the further partial check values 122 of the already received subsets. In this case, the common check value 116 is not determined until the partial check values 114 have been received by the check value determining means 114.
• the device 104 for using the data set can be configured to already use the data set 112 or subsets of the data set 112 before a check result 124 has been received.
• the device may 104 to use the amount of data to interrupt use of the amount of data when atician ⁇ result 124 is received that a mismatch of a partial test value 114 with another partial test value 122 or a mismatch of the common strigwer ⁇ tes 116 with the comparison check value 118 indicates.
• FIG. 2 shows a schematic representation of a device for determining a test value according to an exemplary embodiment of the present invention.
• the device for determining a test value is designed to provide partial test values 114 and a comparison test value 118 which can be used by the device for checking a data quantity shown in FIG. 1 in order to check an integrity of the data volume.
• the device for determining a test value has a device 206 for determining a partial test value, a device 207 for determining the comparison test value and a device 208 for incorporation.
• the device for determining a test value is designed to receive a data amount 112.
• the data set 112 has a plurality of subsets.
• the device 206 for determining a partial test value is designed to form partial test values 114 from the partial quantities of the received data quantity 112 and to provide them to the device 207 for determining the comparison test value.
• the means 207 for determining the comparison test value are thus provided a partial test value 114 for each subset of the data set 112.
• the partial test values 114 are determined by the means 206 for determining a partial test value from the subsets according to a predetermined determination algorithm.
• means 206 for determining a sub-check value may comprise a means for subdividing the data set (not shown in the figures) in the plurality of Operamen ⁇ gene.
• the means 207 for determining the comparison check value is designed to determine and provide the comparison check value 118 in accordance with a predetermined determination rule from the partial check values 114.
• both the partial test values 114 and the comparison test value 118 are stored or made available for further processing.
• the partial test values 114 are provided to the device 208 for incorporation.
• the means 208 for incorporation is designed to receive the data set 112, to integrate the partial check values 114 into the data set 112 and to provide them as a data set 212 with partial check values.
• the sub-test values 114 are interleaved by the means 208 for incorporation into the dataset 112 such that they are, if possible, evenly distributed in the dataset 212.
• the partial test values 114 in the data set 212 can be arranged together at a predetermined location.
• a storage of the partial test values 114 at a defined location of the data set 212 has the advantage that in a subsequent test of the data quantity 212, the partial test values can first be read out and compared with the comparison test value 118.
• the partial check values 114 can be stored separately from the data set 112. Likewise, the same check value 118 was ⁇ integrated into the data set 112 or also be stored separately.
• the check values are determined by means of cryptographic hash functions.
• the integrity of a large file for example a song in MP3 format, is checked in sections by means of a hash algorithm, a hash value or a check "on the fly" are divided into sections, such as chunks or access units in MPEG-4 encoded audio data corresponding to the subsets.
• the hashing in the device for determining a test value is effected by a separate hashing of the individual subsections. Subsequently, the hash values determined from the sections are stored in a table, which, for. B. is stored together with the data. A new hash is formed via this table of hash values and is used as an actual hash, the so-called master hash. The hash values correspond to the partial test values and the master hash to the comparison test value.
• the division into sections is carried out in sections of suitable or desired size. In this case, a compromise is formed between granularity and additionally required storage effort for the additional hash values.
• the hash values of the sections are stored in one or more tables. The formation of a hash value via the table or the tables with the partial hash values takes place below. The master hash can then be stored externally and is the reference against which will be checked later.
• the first step is to pre-check the table of hashes with the master hash, ie a hash is calculated via the table or the tables with the partial hash values. net and compared to the master hash. Subsequently, using the hash values from the table, an examination of the individual subsections follows. This is done by using the partial hash values from the table to individually examine the sections of the file. The examination of the subsections thus follows in this exemplary embodiment after there is an equality between the master hash and the hash which was calculated using the partial hash values. In this way, already tested sections can already be used while others have not yet been tested.
• a table of partial hash values becomes too large.
• multiple hash tables can be used hierarchically. This means that the first table contains hash values, which in turn are used as master hashes for child tables.
• a sequential list can be created. This means that the last hash value in a table is the master hash for the next table, and so on.
• the DCF object is decomposed into a desired number of sections, the so-called chunks, whereby in each case one or more access units are combined.
• a chunk table with this information is inserted into the DCF object.
• Each of the chunks has a hash calculated using the hash algorithm SHA-1. From all computed hashes a table is formed, and this Ta ⁇ beauty inserted as MPEG-4 atom in the DCF object.
• the hash values table is used to form the master hash, which is stored externally by the DCF object as reference value.
• An integrity check is performed by exposing the MPEG-4 Atom to the table of hash values from the DCF object. will be. Then, hash values are calculated across the table and compared to the master hash. If equal, the use of the DCF object can be continued, otherwise the DCF object is rejected as being changed. If the use of the DCF object continues, then the desired chunk from the DCF object is searched for next and a processing of this chunk takes place, for example its reproduction during a simultaneous check of the hash in this chunk. The simultaneous check of the hash of the corresponding chunk is called "on the fly", and if the hash value of the chunk matches the corresponding value in the hash table, another chunk can be processed the further processing is rejected because of modification of the DCF object.
• test values or checksums of any kind can be formed.
• a parity calculation can be carried out.
• the approach according to the invention can be used for all applications in which a verification of the integrity of data is required. Such applications may be, for example, computer systems or digital message transmission systems.
• the test values can be generated and stored when the data is stored. In a subsequent readout and use of the data, the test values are also read out and used to check the data.
• transmission systems the test values can be calculated directly before transmission of the data and subsequently transmitted together with the data and evaluated in the receiver.
• the data is subdivided into subsets.
• the subsets can be independent or overlap.
• the subsets can be independently decodable or syntactically analyzable.
• the device for checking a data volume may be part of an encoder and the device for determining a test value may be part of a decoder.
• the inventive method for checking a data volume as well as the method according to the invention for determining a test value can be implemented in hardware or in software.
• the implementation can be carried out on a digital storage medium, in particular a floppy disk or CD with electronically readable control signals, which can cooperate with a programmable computer system such that the corresponding method is executed.
• the invention thus also consists in a computer program product with a program code stored on a machine-readable carrier for carrying out the method according to the invention, when the computer program product runs on a computer.
• the invention can thus be realized as a computer program with a program code for carrying out the method when the computer program runs on a computer.

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• 2004
  • 2004-10-15 DE DE102004051771A patent/DE102004051771A1/de not_active Ceased
• 2005
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  • 2005-09-12 AU AU2005297525A patent/AU2005297525C1/en active Active
  • 2005-09-12 JP JP2007536012A patent/JP2008517359A/ja active Pending
  • 2005-09-12 WO PCT/EP2005/009783 patent/WO2006042593A1/de active Application Filing
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  • 2005-09-12 CA CA2583755A patent/CA2583755C/en active Active
• 2007
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