CLIENT COMPUTER FOR QUERYING A DATABASE STORED ON A SERVER VIA A NETWORK

20160253367

14/955212

December 01, 2015

The invention relates to a client computer for querying a database stored on a server via a network, the server being coupled to the client computer via the network, wherein the database comprises first data items and suffix items, wherein each suffix item describes a suffix of at least one first data item of the first data items, wherein for each suffix item a first referential connection exists in the database assigning said suffix item to the at least one first data item comprising the suffix of said suffix item, wherein each suffix item is encrypted with a suffix cryptographic key in the database, wherein each first data item is encrypted with a first cryptographic key in the database, wherein the client computer has installed thereon an application program, the application program being operational to: receiving a search request, the search request specifying an infix search expression, said expression comprising a first wildcard term on the left side of a search criterion and a second wildcard term on the right side of the search criterion, transforming the infix search expression into a prefix search expression by disregarding in the search request the first wildcard term and maintaining the search criterion and the second wildcard term, determine a search interval by transforming the prefix search into a corresponding search interval, performing a prefix search by determining all the encrypted suffix items lying within the search interval, providing to the database a request for providing the one or more encrypted first data items being assigned via the first referential connection to the determined encrypted suffix items, receiving from the database the requested encrypted first data items and decrypting said received first data items.

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16. A client computer for updating a database stored on a server, the server being coupled to the client computer via the network, wherein the database comprises first data items and suffix items, wherein each suffix item describes a suffix of at least one first data item of the first data items, wherein for each suffix item a first referential connection exists in the database assigning said suffix item to the at least one first data item comprising the suffix of said suffix item, wherein each suffix item is encrypted with a suffix cryptographic key in the database, wherein each first data item is encrypted with a first cryptographic key in the database, wherein the client computer has installed thereon an application program, the application program being operational to perform the steps of a) receiving an update first data item, the update first data item comprising a set of successional symbols, b) creating an update suffix item by removing a number of the successional symbols from the left side of the update first data item, the update suffix item being the residual part of the update first data item without the removed symbols, c) encrypting the update suffix item with the suffix cryptographic key for obtaining an encrypted update suffix item and encrypting the update first data item with a first cryptographic key for obtaining an encrypted update first data item, d) providing a storage request to the database, the storage request comprising instructions to store in the database the encrypted update suffix item, the encrypted update first data item and a first referential connection assigning said encrypted update suffix item to the encrypted update first data item, e) repeating steps b)-d) with different numbers of the successional removed symbols, the numbers being in between a minimum and a maximum, wherein the maximum is given by the total number of symbols of the update first data item minus a predefined minimal word length.

17. The client computer of claim 16, wherein the suffix items form a partially ordered set in a first relation of the database, the partial order being formed with respect to the suffix items in non-encrypted form, the application program being operational to perform the steps of i. sequentially requesting and decrypting encrypted suffix items, wherein each request of the sequential requesting is performed by comparing the position of the update suffix item in the partial order with the position of the decrypted suffix items in the partial order, wherein the sequential requesting is performed until a position in the partial order for storing the update suffix item in the first relation is determined, ii. in case a position for storing the update suffix item in the first relation is determined, providing the storage request to the database, the storage request comprising the encrypted update suffix item and the position determined in step i).

18. The client computer of claim 17, wherein step i) comprises: a) requesting a current encrypted suffix item from the database, b) in response to said requesting of the current encrypted suffix item, receiving from the database the current encrypted suffix item, c) decrypting the current encrypted suffix item for obtaining a current decrypted suffix item, d) in case the update suffix item is located at a position in the partial order preceding the current decrypted suffix item, providing a request for determining the availability of a new encrypted suffix item in the first relation immediately preceding the current encrypted suffix item, e) in case the update suffix item is located at a position in the partial order succeeding the current decrypted suffix item, providing a request for determining the availability of a new encrypted suffix item in the first relation immediately succeeding the current encrypted suffix item, f) in case the new encrypted suffix item is available in the first relation, requesting the new encrypted suffix item and in response to said requesting receiving the new encrypted suffix item, and repeating steps c)-f) with the current encrypted suffix item in step c) being the new encrypted suffix item, g) in case the new encrypted suffix item is unavailable in the first relation, encrypting the update suffix item with the first cryptographic key for obtaining an encrypted update suffix item and providing the storage request of step ii) to the server, the storage request comprising the encrypted update suffix item and a position information, the position information instructing the server to store the encrypted update suffix item in the first relation at a position in the partial order immediately preceding or succeeding the position of the current encrypted suffix item, depending if the update suffix item is preceding or succeeding the current decrypted suffix item with respect to the partial order.

19. The client computer of claim 17, wherein step i) comprises: a) requesting a current encrypted suffix item from the database, b) in response to said requesting of the current encrypted suffix item, receiving from the database the current encrypted suffix item, c) decrypting the current encrypted suffix item for obtaining a current decrypted suffix item, d) providing a request for a new encrypted suffix item, wherein the request for the new encrypted suffix item comprises information that the new encrypted suffix item is to be retrieved from a position in the partial order immediately preceding or succeeding the position of the current encrypted suffix item, depending if the update suffix item is preceding or succeeding the current decrypted suffix item with respect to the partial order, and in response to said provision of the request for the new encrypted suffix item, receiving and decrypting the new encrypted suffix item, e) in case the update suffix item is not located at a position in the partial order between the position of the new decrypted suffix item and the current decrypted suffix item, repeating steps c)-d) with the new encrypted suffix item being the current encrypted suffix item in step c), until the update suffix item is located at a position in the partial order between the position of the new decrypted suffix item and the current decrypted suffix item, f) encrypting the update suffix item with the first cryptographic key for obtaining an encrypted update first data item, wherein step ii) comprises g) providing the storage request to the database, the storage request comprising the encrypted update suffix item and a position information, the position information instructing the database to store the encrypted update suffix item in the first relation at a position in the partial order between the new decrypted suffix item and the current decrypted suffix item.

20. A method for updating a databases stored on a server, the server being coupled to the client computer via the network, wherein the database comprises first data items and suffix items, wherein each suffix item describes a suffix of at least one first data item of the first data items, wherein for each suffix item a first referential connection exists in the database assigning said suffix item to the at least one first data item comprising the suffix of said suffix item, wherein each suffix item is encrypted with a suffix cryptographic key in the database, wherein each first data item is encrypted with a first cryptographic key in the database, wherein the method comprises at the client computer: a) receiving an update first data item, the update first data item comprising a set of successional symbols, b) creating an update suffix item by removing a number of the successional symbols from the left side of the update first data item, the update suffix item being the residual part of the update first data item without the removed symbols, c) encrypting the update suffix item with the suffix cryptographic key for obtaining an encrypted update suffix item and encrypting the update first data item with a first cryptographic key for obtaining an encrypted update first data item, d) providing a storage request to the database, the storage request comprising instructions to store in the database the encrypted update suffix item, the encrypted update first data item and a first referential connection assigning said encrypted update suffix item to the encrypted update first data item, e) repeating steps b)-d) with different numbers of the successional removed symbols, the numbers being in between a minimum and a maximum, wherein the maximum is given by the word length of the update first data item minus a predefined minimal word length.

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edspap.20160253367