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Links for 2013-08-23

  • NZ police affidavits show use of PRISM for surveillance of Kim “Megaupload” Dotcom

    The discovery was made by blogger Keith Ng who wrote on his On Point blog ( that the Organised and Financial Crime Agency New Zealand (OFCANZ) requested assistance from the Government Communications Security Bureau (GCSB), the country’s signals intelligence unit, which is charge of surveilling the Pacific region under the Five-Eyes agreement. A list of so-called selectors or search terms were provided to GCSB by the police [PDF, redacted] for the surveillance of emails and other data traffic generated by Dotcom and his Megaupload associates. ‘Selectors’ is the term used for the National Security Agency (NSA) XKEYSCORE categorisation system that Australia and New Zealand contribute to and which was leaked by Edward Snowden as part of his series of PRISM revelations. Some “selectors of interest” have been redacted out, but others such as Kim Dotcom’s email addresses, the mail proxy server used for some of the accounts and websites, remain in the documents.
    So to recap; police investigating an entirely non-terrorism-related criminal case in NZ was given access to live surveillance traffic for surveillance of an NZ citizen. Scary stuff

    (tags: surveillance prism nsa new-zealand xkeyscore gcsb kim-dotcom piracy privacy data-retention megaupload filesharing)

  • “Scalable Eventually Consistent Counters over Unreliable Networks” [paper, pdf]

    Counters are an important abstraction in distributed computing, and play a central role in large scale geo-replicated systems, counting events such as web page impressions or social network “likes”. Classic distributed counters, strongly consistent, cannot be made both available and partition-tolerant, due to the CAP Theorem, being unsuitable to large scale scenarios. This paper defines Eventually Consistent Distributed Counters (ECDC) and presents an implementation of the concept, Handoff Counters, that is scalable and works over unreliable networks. By giving up the sequencer aspect of classic distributed counters, ECDC implementations can be made AP in the CAP design space, while retaining the essence of counting. Handoff Counters are the first CRDT (Conflict-free Replicated Data Type) based mechanism that overcomes the identity explosion problem in naive CRDTs, such as G-Counters (where state size is linear in the number of independent actors that ever incremented the counter), by managing identities towards avoiding global propagation, and garbage collecting temporary entries. The approach used in Handoff Counters is not restricted to counters, being more generally applicable to other data types with associative and commutative operations.

    (tags: pdf papers eventual-consistency counters distributed-systems distcomp cap-theorem ecdc handoff-counters crdts data-structures g-counters)

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