Thursday, March 29, 2012

RFC 6090: Fundamental Elliptic Curve Cryptography Algorithms

RFC 6090Fundamental Elliptic Curve Cryptography Algorithms

This note describes the fundamental algorithms of Elliptic Curve Cryptography (ECC) as they were defined in some seminal references from 1994 and earlier.  These descriptions may be useful for implementing the fundamental algorithms without using any of the specialized methods that were developed in following years.  Only elliptic curves defined over fields of characteristic greater than three are in scope; these curves are those used in Suite B.

Why I don't like using Java

Slimy Java installer bundling ad-ware

My reasons for not liking Java (on the desktop, especially applets):

  • Can't install it without Administrator privileges
  • The installer is huge
  • Java applets feel sluggish, and most of them don't look nice
  • Java applets breaks my normal web viewing experience: odd widgets, captures mouse, can't go back etc.
  • Need to update it every few months because of security concerns
  • They bundle ad-ware, or what I assume is ad-ware because it's checked by default (to trick me into installing), and isn't something I would every install myself

Tuesday, March 27, 2012

Shell programming: pipefail

Today I discovered Bash's pipefail option. For a relevant blog post, see this.

So now all of my Bash scripts will begin with "set -e; set -o pipefail;"

Friday, March 23, 2012

Two current divider rules

Wikipedia has the following current divider rule

$$I_X = \frac{R_T}{R_X + R_T} \times I_T$$

where as certain websites have the following rule:

$$I_X = \frac{R_{total}}{R_X} \times I_T$$


$$\frac{1}{R_{total}} = \frac{1}{R_X} + \frac{1}{R_T}$$

for two resistors, this simplifies to

$$R_{total} = \frac{R_X \times R_T}{R_X + R_T}$$

These two rules are equal:

I_X &= I_T \times \frac{R_{total}}{R_X} \\
&= I_T \times R_{total} \times \frac{1}{R_X} \\
&= I_T \times \frac{R_X \times R_T}{R_X + R_T} \times \frac{1}{R_X} \\
&= I_T \times \frac{R_T}{R_X + R_T}

Thursday, March 22, 2012

ViewVC error parsing rlog output

When trying to list a directory in ViewVC 1.1.13, I was getting the error:

An Exception Has Occurred

Python Traceback

Traceback (most recent call last):
File "/usr/share/viewvc/lib/", line 4537, in main
File "/usr/share/viewvc/lib/", line 394, in run_viewvc
File "/usr/share/viewvc/lib/", line 2049, in view_directory
file_data, options)
File "/usr/share/viewvc/lib/vclib/ccvs/", line 261, in dirlogs
alltags = _get_logs(self, path_parts, entries_to_fetch, rev, subdirs)
File "/usr/share/viewvc/lib/vclib/ccvs/", line 1030, in _get_logs
raise vclib.Error('Error parsing rlog output. Expected RCS file %s'
Error: Error parsing rlog output. Expected RCS file /cvs/project/some/path/,v, found

After tracking this down, turns out that if the last line of your commit is:


then you will get two back-to-back lines of all "=" in the rlog output, and ViewVC parsing will fail.

So, until this is fixed in ViewVC, you can edit the *,v files, and change the first character of the line from a "=" to something else.

Tuesday, March 13, 2012

"Is copyright infringement theft?" is the wrong question

This particular trained lawyer wishes that we could never talk about whether cop... | Hacker News: There are laws against stealing physical property. Copyright infringement doesn't violate them. There are laws against copyright infringement. Copyright infringement does violate them. The question of whether "stealing" is good shorthand for "copyright infringement" is a total waste of time. The real point is whether the copyright infringement laws are good laws. ... So when we talk stealing and infringement, we're talking about violations of someone else's alienable rights. When you take away all of my alienable rights over my bike, that's called stealing. When you take them temporarily, it's "wrongful appropriation." When you take my right to exclude people from my property, that's called trespass. When you take my right to decide who rents my bike, it's theft of services. When you take my right to decide where this comment gets published, it's copyright infringement.

Friday, March 9, 2012

A Princess of Mars

A Princess of Mars - Wikipedia, the free encyclopedia: Dejah Thoris: A red Martian princess of Helium, she is courageous, resolute, and frequently in mortal danger or under threat of dishonor by the lustful designs of a succession of villains.
Best description of a Disney princess I've read.