Abstract: A method for quantifying the relative degree of uniqueness of an indicated data item in a repository of data items stored at locations associated with their digital fingerprints.

Abstract: In general, the invention features methods by which more-than one client program connected to a network stores the same data item on a storage device of a data repository connected to the network. In one aspect, the method comprises encrypting the data item using a key derived from the content of the data item, determining a digital fingerprint of the data item, and storing the data item on the storage device at a location or locations associated with the digital fingerprint. In a second aspect, the method comprises determining a digital fingerprint of the data item, testing for whether the data item is already stored in the repository by comparing the digital fingerprint of the data item to the digital fingerprints of data items already in storage in the repository, and challenging a client that is attempting to deposit a data item already stored in the repository, to ascertain that the client has the full data item.

Abstract: In general, the invention features methods by which more than one client program connected to a network stores the same data item on a storage device of a data repository connected to the network. In one aspect, the method comprises encrypting the data item using a key derived from the content of the data item, determining a digital fingerprint of the data item, and storing the data item on the storage device at a location or locations associated with the digital fingerprint. In a second aspect, the method comprises determining a digital fingerprint of the data item, testing for whether the data item is already stored in the repository by comparing the digital fingerprint of the data item to the digital fingerprints of data items already in storage in the repository, and challenging a client that is attempting to deposit a data item already stored in the repository, to ascertain that the client has the full data item.

Abstract: A method by which a disk-based distributed data storage system is organized for protecting historical records of stored data entities. The method comprises recording distinct states of an entity, corresponding to different moments of time, as separate entity versions coexisting within the distributed data storage system, and assigning expiration times to the entity versions independently within each of a plurality of storage sites according to a shared set of rules, before which times deletion is prohibited.

Abstract: A method by which a disk-based distributed data storage system is organized for protecting historical records of stored data entities. The method comprises recording distinct states of an entity, corresponding to different moments of time, as separate entity versions coexisting within the distributed data storage system, and assigning expiration times to the entity versions independently within each of a plurality of storage sites according to a shared set of rules, before which times deletion is prohibited.

Abstract: A method for constructing an index suitable for indexing a large set of records identified by long generally randomly distributed record names and for answering membership queries about the set, the method comprising assigning each different record a different record name, determining that a new record name is not already represented in the index by checking an entry in a first level index that is shorter than the complete new record name, and determining that a queried record name is already represented in the index by determining that the queried record name is represented in a second level index that contains enough information to reconstruct the complete queried record name.

Abstract: In general, the invention features methods by which more than one client program connected to a network stores the same data item on a storage device of a data repository connected to the network. In one aspect, the method comprises encrypting the data item using a key derived from the content of the data item, determining a digital fingerprint of the data item, and storing the data item on the storage device at a location or locations associated with the digital fingerprint. In a second aspect, the method comprises determining a digital fingerprint of the data item, testing for whether the data item is already stored in the repository by comparing the digital fingerprint of the data item to the digital fingerprints of data items already in storage in the repository, and challenging a client that is attempting to deposit a data item already stored in the repository, to ascertain that the client has the full data item.

Abstract: An index is constructed that is suitable for indexing a large set of records identified by randomly distributed record names and for answering membership queries about the set. The index has more than one level and the first-level index typically resides in RAM. Like a Bloom Filter, the first level index provides a non-membership indication with certainty and a membership indication with a controlled probability of error. Unlike a Bloom filter, entries in the first level index correspond uniquely to distinct records. Use is made of the statistical properties of a sorted list of random numbers in order to represent the first level index compactly.

Abstract: In general, the invention features methods by which more than one client program connected to a network stores the same data item on a storage device of a data repository connected to the network. In one aspect, the method comprises encrypting the data item using a key derived from the content of the data item, determining a digital fingerprint of the data item, and storing the data item on the storage device at a location or locations associated with the digital fingerprint. In a second aspect, the method comprises determining a digital fingerprint of the data item, testing for whether the data item is already stored in the repository by comparing the digital fingerprint of the data item to the digital fingerprints of data items already in storage in the repository, and challenging a client that is attempting to deposit a data item already stored in the repository, to ascertain that the client has the full data item.

Abstract: A method for providing naming and access control of data items in a data repository, the method comprising having a first client program deposit a data item in the data repository, the depositing including determining a digital fingerprint from the data item, and storing the data item in the data repository at a location or locations associated with the fingerprint, having the first client program specify an object name for an object that comprises a set of data items, storing in the repository an association between the name and the set of data items, and allowing the client program to retrieve a data item from the set of data items by specifying the object name and without providing the digital fingerprint of any data item or composite of data items.

Abstract: A method by which a disk-based distributed data storage system is organized for protecting historical records of stored data entities. The method comprises recording distinct states of an entity, corresponding to different moments of time, as separate entity versions coexisting within the distributed data storage system, and assigning expiration times to the entity versions independently within each of a plurality of storage sites according to a shared a set of rules, before which times deletion is prohibited.

Abstract: In general, the invention features methods by which more than one client program connected to a network stores the same data item on a storage device of a data repository connected to the network. In one aspect, the method comprises encrypting the data item using a key derived from the content of the data item, determining a digital fingerprint of the data item, and storing the data item on the storage device at a location or locations associated with the digital fingerprint. In a second aspect, the method comprises determining a digital fingerprint of the data item, testing for whether the data item is already stored in the repository by comparing the digital fingerprint of the data item to the digital fingerprints of data items already in storage in the repository, and challenging a client that is attempting to deposit a data item already stored in the repository, to ascertain that the client has the full data item.

Abstract: A method by which a disk-based distributed data storage system is organized for protecting historical records of stored data entities. The method comprises recording distinct states of an entity, corresponding to different moments of time, as separate entity versions coexisting within the distributed data storage system, and assigning expiration times to the entity versions independently within each of a plurality of storage sites according to a shared set of rules, before which times deletion is prohibited.

Abstract: A method for protecting history in a file system in which rules governing which versions of files must be retained, and for how long, are enforced by one or more storage systems attached to a network, the method comprising associating with a storage system a time standard configured to prevent the accuracy of the time standard from being manipulated over the network, storing file information in the storage system, with files stored as objects adapted for separate retrieval in any order, storing, in the storage system, directory information which is sufficient to allow files to be retrieved starting from file system pathnames, marking at least some versions of files as archival file versions not subject to further change, and assigning an expiration time to each of at least some of the archival file versions, preventing storage system clients from deleting archival file versions before their expiration times, and allowing individual archival file versions that have passed their expiration times to be deleted a

Abstract: In general, the invention features methods by which more than one client program connected to a network stores the same data item on a storage device of a data repository connected to the network. In one aspect, the method comprises encrypting the data item using a key derived from the content of the data item, determining a digital fingerprint of the data item, and storing the data item on the storage device at a location or locations associated with the digital fingerprint. In a second aspect, the method comprises determining a digital fingerprint of the data item, testing for whether the data item is already stored in the repository by comparing the digital fingerprint of the data item to the digital fingerprints of data items already in storage in the repository, and challenging a client that is attempting to deposit a data item already stored in the repository, to ascertain that the client has the full data item.