Whitelists and Blacklists (by alaric)

In my previous post, I spoke of technologies that prevent [email spoofing](E-mail spoofing) by reliably tying the mail server sending a message to a domain, or checking that the message is from who it claims to be from.

These measures alone can reduce spam - in the short term - because, right now, lots of spam is spoofed. But as these technologies spread, spammers will set up lots and lots of domains, put valid SPF and CSV records in them, and start spamming.

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CSV vs SPF vs DomainKeys (by alaric)

There are a number of technologies vying to protect us from spam, by providing channels for legitimate senders of email to prove that any given message comes from them, thus allowing them to build a reputation (and get whitelisted) while spammers' domains and/or mailserver IPs get bad reputations, and they can't spoof messages to steal the good reputations of others.

This is entirely separate to tools like SpamAssassin, which try to analyse emails once they've arrived, and allow a recipient to judge their spaminess regardless of who they've come from.

It's also entirely separate from things like HashCash, which work by letting senders attach a mathematical proof to their message that shows they've invested a second or so of computer time, thus distinguishing them from people who send thousands of messages per second.

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Designing for unit tests (by alaric)

I'm writing a unit test for a bit of code that connects to a server. The bit of code has parameters - hostname, username, password, and details of what to fetch from the server.

The thing is, the infrastructure it's placed in expects it to store the password in encrypted form. It has to use a separate component that contains a hidden master key to decrypt the password when it's required, and to encrypt a new password given to it.

Also, since the application will be fetching lots of different things from different servers, it quite reasonably has a 'host' abstraction that can be referred to by lots of data collection modules; it keeps a central list of hosts, and my component is passed a Host object.

But when writing a unit test for my component, this is a pain. The way the central list of hosts and the crypto component are accessed involves going through a 'session' object that also has lots of things like listening sockets, database connections, and much other complexity afoot.

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EmDrive (by alaric)

A British chappy claims to have built an reactionless engine, the EmDrive - I just read about it in New Scientist today, so threw up the Wikipedia page about it.

Any physicists around here who are able to do the maths and see if his claim (that a truncated-conical resonant cavity full of microwaves will experience an asymmetric photon pressure due to the group velocity of the waves changing as the local diameter of the tube varies, thanks to some relativistic effects) holds water?

And if it does, what becomes of conservation of momentum?

Accessing a Domino server from Java (by alaric)

For a project, I'm having to write some Java code to talk to a Domino server.

Finding any references on how to do this is a BIG pain, so for posterity, here is what I've found.

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