Saulo Silva's Blog

I support Barack Obama. That is all.
Edit: Obama is the new elect-president! Congratulations!

Google confirmed tomorrow’s launch of Google Chrome beta, a new open source web browser that borrows the rendering engine from Apple’s WebKit and components from Mozilla Firefox.

An important design aspect behind Google Chrome is that each tab will be assigned an entire process instead of a thread within a process. This means that if a particular website causes the page to hang, only its tab will have to be closed. In addition, a task manager will allow the user to see which page, plug-in or web application is consuming system resources, a feature available in all modern OSs.

Google has published a comic that explains in 38 pages their web browser project.

How will this affect the battle for market share between existing web browsers? Will Google Chrome be adopted by Firefox or IE users?

Update 1: added a screenshot (found at TechCrunch).
Update 2: The Google Chrome webpage is up.

After realizing that I would never match the power of hundreds of developers behind WordPress’ success, I decided to ditch my own custom, ad hoc content management system. PensCMS had been around for eight years, and I had just successfully solved the spam problem with reCAPTCHA (I know, I should have thought about that before!). The other thing that really bothered me with my own blogging software is that in order to add images to a post, I had to manually resize, upload via FTP and paste the code for them, which was a painful process to say the least.

I prefer to always include at least an image with my posts, so this was a big issue for me.  As I thought about a solution, I had a sudden spark of humbleness: maybe it’s OK to use other people’s work instead of doing it all myself from the ground up.

After some research, I narrowed down to two options: WordPress and Blogger. The reason why I chose the former is that I wanted to transfer all my posts and comments from my old blog. The easiest way of doing so (although a bit long and tedious) was to manually add them to the database. The other option was to convert all posts and comments to XML—which I did—but I was unable to import into Blogger. Besides, there is no way of creating the about and quotes pages on the Google-maintained blogging system.

I spent the whole day yesterday moving posts and comments, customizing the Simpla theme and installing plug-ins. I left behind some posts that were either too old or too silly—I did keep the ones that were chronologically interesting such as the post on how Firebird (now “Firefox”) was good alternative to IE.

I am happy with the results and I will try to write more often now that I don’t have to open Paint.NET and FileZilla in order to post an article!

In public-key Cryptography, especially with the RSA algorithm, the Chinese Remainder Theorem is often used. Say you have a system of simultaneous congruences as follows

x a₁ mod m₁
x a₃ mod m₂

x a_k mod m_k ,

where m₁, m₂, …, m_k are coprime, i.e. gcd(m₁, m₂, …, m_k) = 1. How can we solve for x? The solution is quite straight forward, but could involve a fair amount of calculations. I find that breaking down the method into smaller steps makes it easier to find and fix mistakes. By the Chinese Remainder Theorem, the solution to that system of equations is

x = (a₁M₁y₁ + a₂M₂y₂ + … + a_kM_ky_k) mod M ,

where M_i is the product of all m’s except for m_i

,

y_i is the multiplicative inverse of M_i modulo m_i

y_i M_i^-1 mod m_i ,

and M = m₁ * m₂ * … * m_k .

Let us try a numeric example. Here is a system of simultaneous congruences:

x 12 mod 25
x 9 mod 26
x 23 mod 27

We start by calculating M₁ and y₁:

M₁ = m₂ * m₃ = 26 * 27 = 702

y₁ = M₁^-1 mod m₁ = 702^-1 mod 25 .

We apply the Extended Euclidean Algorithm to find the multiplicative inverse of 702 relative to 25:

702 = 28 * 25 + 2 → 2 = 702 – 28 * 25
25   = 12 * 2 + 1 → 1 = 25 – 12 * 2
= 25 – 12 * (702 – 28 * 25)
= 337 * 25 – 12 * 702

Then y₁ = 702^-1 mod 25 -12 13.

The same calculations can be carried on to find M₂ = 675, y₂ = 25, M₃ = 650 and y₃ = 14. Now it is just a matter of plugging in the values into the equation:

x = (a₁M₁y₁ + a₂M₂y₂ + a₃M₃y₃) mod M
= (12*702*13 + 9*675*25 + 23*650*14) mod 17550 470687 14387

To verify our answer we can plug that number back into the system:

470687 mod 25 12
470687 mod 26 9
470687 mod 27 23

Related links:

• March of the monks
• Myanmar troops kill 9 protesters – Reuters
• Nine killed in Burmese crackdown – BBC
• Canadian friends of Burma
• US Campaign for Burma
• Burma Campaign UK

This Monday I had yet another renal calculus crisis—the second one in less than 12 months. There was I, in the emergency section of the local hospital contorting in pain from 18:30 to 22:30. By 23:00 the stone had moved from my ureter to my bladder, which reduced the pain, and by the next day it finally got expelled from my system. After a blood test and an x-ray, the doctor said I had to drink more water and reduce the salt in my diet. I am considering taking Herba Desmodii capsules, a natural diuretic, which a co-worker said does wonders to kidney stones.