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Links for 2012-12-14

  • Authentication is machine learning

    This may be the most insightful writing about authentication in years:

    From my brief time at Google, my internship at Yahoo!, and conversations with other companies doing web authentication at scale, I’ve observed that as authentication systems develop they gradually merge with other abuse-fighting systems dealing with various forms of spam (email, account creation, link, etc.) and phishing. Authentication eventually loses its binary nature and becomes a fuzzy classification problem.

    This is not a new observation. It’s generally accepted for banking authentication and some researchers like Dinei Florêncio and Cormac Herley have made it for web passwords. Still, much of the security research community thinks of password authentication in a binary way [..]. Spam and phishing provide insightful examples: technical solutions (like Hashcash, DKIM signing, or EV certificates), have generally failed but in practice machine learning has greatly reduced these problems. The theory has largely held up that with enough data we can train reasonably effective classifiers to solve seemingly intractable problems.

    (via Tony Finch.)

    (tags: passwords authentication big-data machine-learning google abuse antispam dkim via:fanf)

  • Hotels to pay royalties on music – The Irish Times – Fri, Dec 14, 2012

    ‘The operators of hotels, guesthouses and bed & breakfasts will have to pay royalties for any copyright music played in guest bedrooms [in Ireland]. […] Under the agreement, the music charges will be set by Phonographic Performance Ireland Ltd (PPI). […] When it initiated its case in 2010, the PPI said it was seeking payment of about €1 per bedroom per week or about 14 cent a night.’ I don’t understand this. Most hotels do not play music in the rooms themselves. Does this apply if there is no music playing in the bedroom? Does it apply if the customer brings their own music? Are Dublin Bus to be next?

    (tags: hotels ppi ireland music money royalties)

  • The Mathematical Hacker

    ‘The trouble with the Lisp-hacker tradition is that it is overly focused on the problem of programming — compilers, abstraction, editors, and so forth — rather than the problems outside the programmer’s cubicle. I conjecture that the Lisp-school essayists — Raymond, Graham, and Yegge — have not “needed mathematics” because they spend their time worrying about how to make code more abstract. This kind of thinking may lead to compact, powerful code bases, but in the language of economics, there is an opportunity cost.’

    (tags: mathematics coding maths essay hackers lisp fortran)

  • The Aggregate Magic Algorithms

    Obscure, low-level bit-twiddling tricks — specifically:

    Absolute Value of a Float, Alignment of Pointers, Average of Integers, Bit Reversal, Comparison of Float Values, Comparison to Mask Conversion, Divide Rounding, Dual-Linked List with One Pointer Field, GPU Any, GPU SyncBlocks, Gray Code Conversion, Integer Constant Multiply, Integer Minimum or Maximum, Integer Power, Integer Selection, Is Power of 2, Leading Zero Count, Least Significant 1 Bit, Log2 of an Integer, Next Largest Power of 2, Most Significant 1 Bit, Natural Data Type Precision Conversions, Polynomials, Population Count (Ones Count), Shift-and-Add Optimization, Sign Extension, Swap Values Without a Temporary, SIMD Within A Register (SWAR) Operations, Trailing Zero Count.
    Many of these would be insane to use in anything other than the hottest of hot-spots, but good to have on file. (via Toby diPasquale)

    (tags: hot-spots optimisation bit-twiddling algorithms via:codeslinger snippets)

  • Shell Scripts Are Like Gremlins

    Shell Scripts are like Gremlins. You start out with one adorably cute shell script. You commented it and it does one thing really well. It’s easy to read, everyone can use it. It’s awesome! Then you accidentally spill some water on it, or feed it late one night and omgwtf is happening!?
    +1. I have to wean myself off the habit of automating with shell scripts where a clean, well-unit-tested piece of code would work better.

    (tags: shell-scripts scripting coding automation sysadmin devops chef deployment)

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