Jan 19

A basic guide to encryption -1

Encryption ? What is it? What’s its relevance to you? Do you think you have never used any kind of an encryption method? If your answer is “no”, definitely you are mistaken!. We use encryption in many events of our day-to-day life. Specially as Internet users encryption helps us a great deal. We are just ignorant about its services. As an example, when you login to your mail account/facebook account you are receiving the protection of encryption methods. We benefit from encryption even in our day-to-day activities like using the ATM. Without the use of encryption technologies, use of ATM machines would have been far more riskier. Through this series of articles, I’m going to give you an introduction to encryption and a basic introduction to some encryption categorizations.

First of all, let’s get familiarized with the terminology.

Cryptography:

This is the study of creating messages in a form of secret code that masks the actual message and displays something completely different. Usually complex mathematical algorithms and computers are used to do this. This encrypted message will mean nothing to a casual observer, but the intended receiver can reconstruct the original message using a certain predefined methodology.

Plaintext:

A data set prior to the encrypting it is called “plaintext”.

Encryption:

Encryption is the implementation of cryptography. Data is converted to an encrypted format using encryption. This encrypted data could be password protected. To decrypt( that means to retrieve the original data) the receiver should have the proper key and/or password.

Ciphertext:

Plaintext data is called “ciphertext” once it is encrypted.

Algorithm:

An algorithm is a precise set of instructions that can be followed to get a reasonable output to a problem. As an example, when sound doesn’t come from your computer speakers, you first check the volume controller of the computer, then you check whether the speaker system has got the power correctly, then you check the volume controller of the speaker system, then you check the connection between the computer and the speaker system. This is more like an “if-then” procedure.

Cipher:

It’s an algorithm that contains precise instructions on how to encrypt and decrypt data. There are two main types of cyphers. The first one rearranges the characters in a file. As an example, the word “ishan” could be rearranged as “snahi”. The second method completely changes the content and replaces it with predeifned characters. As an example, the word “ishan” can be encrypted as “abcde” where i=a, s=b, h=c, a=d, n=e .

Pseudorandomness:

If a process seems to be random, but if it is not random, then thats called pseudorandomness. If a series of things( lets say numbers) seems to be random, but if they are not random, the it’s called a pseudo random series.

Keystream:

It’s a collection of random or pseudorandom characters that is combined with a plaintext message to produce an encrypted message (the ciphertext).

Key:

This is a parameter which determines the functional output of a cryptographic algorithm or cipher. A key is essential to get a result that is useful.

Brute force attack:

When a person tries to crack the encryption algorithm by using an intensive trial-and-error key/password reproduction procedure, it is called a brute force attack.

I think this is enough for a single post. Hope to you see you soon with the next part of this article…!

Share Button
Jan 18

Create custom error pages in cPanel

As we know, when we connect to a web server, if some error occurs, the server will show us some error message. As an example if the web page we are requesting is not available in the server it will generate a 404-page not found error. But as you have noticed, in most cases this error page is just a simple page which most probably has a white background with some simple text formatting. But do you know that you can customize those error pages as you like? Give it a theme( as an example, the theme of the webs site it self)? In this article I’m going to show you how to customize these error pages in a web server where you have access to cPanel. There are two methods to do this.

1st method:

Log in to cPanel. Then go to Advanced → Error pages . There you will find a list of various error pages that cPanel currently has. Click on any one of them and you will be directed to a page where you can customize the page using usual html syntaxes .

2nd method:

If you want to replace the error page with a page that you have already designed, the easiest way to do so is to upload it to the server and replace the relevant file. The relevant files for the error pages can be found in the public_html folder. These files have the .shtml extension. So make sure that you rename the .html file that you are uploading to the .shtml extension. Here are some names of the error pages.

  • 400.shtml : Bad request
  • 401.shtml : Authentication required
  • 403.shtml : Forbidden
  • 404.shtml : Page not found
  • 500.shtml : Internal server error

You will be able to find an example customized 404 page in http://ishans.info/wrongURL

Share Button
Jan 17

Weird WordPress problem: Wp-admin redirects to localhost

Have you experienced this weird problem? It most probably occurs when you develop your wordpress blog in your local server and upload the blog to your Internet web server. I too faced this problem when I uploaded my blog to my Internet server. Here’s how I got around it.

To rectify this problem in my way ( 😉 ) you need access to the database which is used by your blog. I used phpMyAdmin to access the database of the blog. You can use any other tool you like. You need to edit an entry in a table of the database to rectify the problem.

First access the database and go to the table named wp_options ( sometimes this could be named as options too). There , you will find an entry named siteurl . You will see that this entry has the value( option_value) http://localhost/yourWpFolder . You need to edit this entry to your blogs URL. As an example, in my case I edited it as http://blog.ishans.info . After setting the value, click on Go and you’ll get a message saying the change was successfully done. Now you’ll see that “http://mySite.xxx/wp-admin” address is working.

But it’s not over yet. You need to set another setting in wordpress settings too. Log in as the Administrator to the wordpress dash board and go to Settings . In here you’ll see that the entry WordPress address (URL) is set to “http://mySite.xxx” , but the entry Site address (URL) is still http://localhost/yourWpFolder . So you need to set the Site address (URL) entry to “http://mySite.xxx” .

Thats it…!. Now save your settings and you’ll see that the whole site is working perfectly ( If it doesn’t have any other errors of course 😉 )…..! 😀

Share Button