Overheating of the computer and laptop can be an important sign of system malfunction, especially in the case of laptops. This may be due to excessive dust and lack of proper airflow.

Not paying attention to the heat of the laptop and the system is exactly the best way to destroy the system, but in addition, too much heat can disrupt the performance of various components of the system.

For example, heat can greatly affect the system hard drive. So if you have problems with the hard drive, it is better to pay attention to the temperature of your system first.

To know the system temperature and internal components, there are free software, which we want to introduce to you three of the best software in this field.

The best computer temperature measuring software

1- CrystalDiskInfo software

If you want to professionally check the system hard drive temperature, the best software available is CrystalDiskInfo software. This software is specially designed for hard drive and SSD health management.

The user interface of this software is very simple and on the other hand, it displays information about the health of the hard drive and SSD in a clear and understandable way. Among the features of CrystalDiskInfo software we can mention the following:

Temperature assessment of all system hard drives and SSDs

Estimate the overall health status of hard drives and SSDs according to each of them

Ability to check all read and write memories

You can download CrystalDiskInfo software from this link .

2- Core Temp software

Core Temp software, however, is fast, accurate and flexible software for measuring and monitoring the temperature of the laptop. This software is available for free for 32-bit and 64-bit Windows and as an installation or portable. But during installation, be sure to uncheck the installer comes with bundleware. Among the most important features and capabilities of this laptop heat measurement software, we can mention the following:

Display information in real-time and in real time

1- Ability to select sensors to display on the screen

2- Display notification when the temperature is too high

3- Checking the system for updating drivers and BIOS

You can download Core Temp system temperature measurement software for Windows for free from this link .

3- HWMonitor software

One of the most reliable system temperature measurement software is HWMonitor software. The free version of this software is really useful for normal use, but in any case, if you need very detailed information, you can buy a professional version called HWMonitor Pro. Mention the following:

1- Identify each sensor with voltage, fan and temperature

2- Save the data obtained from the temperature monitor and logging for troubleshooting

3- Checking the system to be informed about driver updates and BIOS

HWMonitor software for Windows is available in two versions 32-bit and 64-bit and both installed and portable.

There are other software in the field of system temperature measurement, among which we can mention Macs Fan Control , SpeedFan , Open Hardware Monitor , NZXT CAM and HWiNFO .

Which software do you have experience with and which do you prefer over others? Share your comments and experiences with us and other Facebook users .

Surely you are familiar with the anonymous mode feature in Chrome browser, Firefox, etc., which has been provided to protect users. Now, almost since last year, Google has been equipped with such a feature, but perhaps less attention. Now in this article, we are going to teach you how to activate this feature in Google Map.

Steps to enable incognito mode in Google Maps

Enabling incognito mode in Google Maps is very simple. To do this, just follow the steps below:

1- Enter the Google Map application on your phone and tap on your profile picture to display the settings menu.

2. Now you see that the first option in the menu is to turn on Incognito mode . Tap this option.

3. Now a window will appear that explains the features of incognito mode. By closing this window you will enter the incognito mode of Google Map.

Note that to use incognito mode Google Maps must close button or Close select If more options or learn more to choose from, you will exit incognito mode.

After a long wait, an hour ago Google finally introduced the Nearby Share feature, which is a competitor to AirDrop, for the Android operating system, and now some users of Pixel and Samsung phones can use this feature to quickly send their files to nearby devices. To use.

This feature is available on Android 6.0 and above for Android users to send files, images, videos, links, etc. to their nearby devices at high speed and with security. 

Using this feature is very simple and in fact a list of devices around you that support Nearby Share is displayed that by selecting one of these devices, you can transfer your data to the device you want.

 Of course, on the recipient side, a notification is displayed that the other party can accept and receive your file. Now the Nearby Share feature will automatically select the best option from the available protocols such as Bluetooth, Bluetooth Low Energy, Peer to Peer Wi-Fi, etc., and even if you are not connected to the Internet.

In designing this feature, special attention has been paid to privacy so that you can send or receive files anonymously. You can also specify that you hide from certain contacts.

This feature will also be available for Chromebooks in the coming months, so you will soon be able to share your files between Android and Chromebook easily and quickly. So it will be very easy to communicate between Android and Chromebook.

As we said, a number of Google Pixel and Samsung phones are the first Android phones to receive Nearby Share feature from today. But this trend will continue until the coming weeks, and soon all Android phones above 6.0 will benefit from this feature.

Instagram Dark Modeis one of the most popular social networks in the world, which also has many fans in our country. Recently, this social network has been equipped with a feature called Dark Mode. But what is the use of It and how is it activated?

Instagram Dark Mode application

This feature is originally designed with the aim that users who want to use the phone at night and in the dark, not only do not create a lot of light, but also do not damage the eyes due to this light. In fact, this dark theme makes the blue light less harmful.

On the other hand, this feature makes the separation of colors in the Instagram environment, which is full of photos and videos, better.

However, another positive point about activating this feature is that it significantly reduces the phone’s battery consumption. However, we recommend that you use this feature on your phone and on Instagram, which itself consumes a lot of battery.

Activate Instagram Dark Mode on Android

To use this feature on Android phones, you must first make sure you have the latest version of Instagram installed on your phone. Then just follow the steps below:

1- Enter the setting section and tap on the Theme option .

2. Now select the Dark option .

It is simply activated for you.

Activate Instagram Dark Mode on iOS

Keep in mind that you must have at least iOS 13 to enable the Instagram Dark theme on iOS. Also have the latest version of Instagram installed on your phone. Now follow the steps below:

1- On iPhone on Instagram, go to Settings> Display & Brightness .

2- Now you can set the dark mode to ON or OFF.

3- You can also set it to automatic mode to change itself to dark or light depending on the ambient light. Of course, you can also manually program for this mode.

Instagram Dark Mode is easily activated for your iPhone. Of course, iOS itself allows you to generally put the phone in dark mode.

Cryptography, In the previous article of the Proceedings of the principles of information security with the key concepts of information security were introduced.

In this article, we start the topic of cryptography, and after getting acquainted with the basic definitions in this field, we examine the simple substitution method to use it to say what is meant by a secure cryptography method.

Remember these words

First of all, it is better to get acquainted with the definition of these words. Knowing these terms will help you to know exactly what they mean, especially if you come across them in specialized texts, and secondly, if you want to read more about these topics, you know exactly what phrases to look for.

Cryptology : Knowledge of making and breaking secret codes.

Cryptography : Knowledge of creating secret codes.

Cryptanalysis : Knowledge of breaking secret codes

You may also come across the word Crypto in specialized texts, which can mean any of the above three words. Depending on the text, you can tell which meaning is meant.

One crypto system ( Crypto System – Cipher ) receives the original data as input and returns another data as output, which is equivalent to the encrypted original data. So the original data as input to the system is encrypted plain text ( Plain text ) say and the encryption system output ciphertext ( Cipher text ) is called.

A procedure that converts plain text to ciphertext Encryption ( Encryption ) and it’s contrary to the plain text into ciphertext decryption ( Decryption ) is called. Also in the operation of a key ( Key) Is also used to configure the cryptographic system. The following figure gives a better understanding of the above definitions.

Cryptographic methods are divided into two general categories, symmetric and asymmetric.

In symmetric encryption ( Symmetric cipher ) is a key for encryption and decryption operations.

When using this method, the key must be kept confidential because anyone who has access to the key can convert the ciphertext to plain text. Unlike the procedure in asymmetric cryptography ( Asymmetric ) of the two keys are used.

One key to encrypt information and the other key to decrypt. When this encryption method is used, the key used for decryption is usually made available to the public and the other key is kept confidential. That’s why these two keys, public key ( Public Key ) and the private key( Private Key ) is called.

When someone uses public key to decrypt information, they can ensure that the information is encrypted by the same person who holds the private key and is not manipulated by someone else. In this way encryption, encrypted with the public key ( Public key encryption ) is also called.

In an encryption system ideal ( Ideal Cipher ) to obtain the plaintext and ciphertext using the keyless impossible.

The security of a cryptographic system must be key-based. For added security, details of how the cryptographic system works should not be hidden. In fact, everyone should be able to have accurate information about how the cryptographic system works, and all that needs to be hidden is the key. This is known as the Kirkhoff principle , which should be considered in the design of cryptographic systems.

Substitution Cipher

You must remember Jafar, Morteza and Javad from the first article.

Morteza wants to send a message to Jafar Bank and in this message his transaction information is written. Jawad Ibn is able to listen to the messages exchanged. For this reason, Morteza can not send the original message to Jafar Bank.

You have to provide him with an encryption system so that even if the message being exchanged is in Javad’s possession, Morteza’s account information will not be revealed.

To do this we can use a simple encryption system called substitution cipher ( Substitution Cipher ) use.

In this cryptographic system, we use another letter instead of each letter of the alphabet. In its simplest form, instead of each letter of the alphabet, we use another letter that is a certain number after that letter. And In this case, the space between the main letter and the letter that replaces it is used as the encryption key.

The following figure shows how to replace the letters.

In this example, instead of each letter, the letter in the alphabetical order of 3 is used, so here is the cryptographic key 3.

This encryption system is known as Caesar encryption when used with key 3. In ancient Rome, this method was used to encrypt confidential information.

According to the figure above, if n = 3 is used as the encryption key Message: thisismorteza is encrypted as WKLVLVPRUWHCD. To decrypt it, it is enough to do the opposite. That is, instead of each letter in the encrypted message, we put the 3 letters before it in alphabetical order.

By doing this, can we be sure that if Javad receives the encrypted message, he will not be able to understand the content of the original message?

Another issue that needs to be taken as the key ( Key Space ) is. Key space means all values ​​that may be used as encryption keys. In the simple substitution cryptography method we examined, in English, given that there are 26 letters in the alphabet, the key can have values ​​from 0 to 25. As a result, the size of the key space in this method is equal to 26.

Thus, if Javad knows that simple substitution encryption has been used, in order to obtain the encryption key, he must try all 26 possible values ​​to obtain the key. It’s not difficult to try all these 26 keys. So we can not say that this encryption mechanism provides sufficient security.

This type of attack where all the switches are looking for real value encryption key is searched comprehensive search key ( Exhaustive search key ) is called.

How big should the key space be?

We have seen that simple substitution encryption is not a good way to encrypt information,

because there is only one value that can be used as a key, and thus anyone who wants to break this encryption only needs to use these 26 values ​​as a one-to-one key. Do an experiment to find the right key.

But how big does the key space really have to be to make sure encryption can’t be attacked this way?

Suppose Javad’s computer has enough computing power to test 2.40 keys per second.

In this case,

if the number of possible keys is 2.5 x 56, it only takes 2.16 seconds, which is about 18 hours for Javad to try all possible keys and find the right key.

Similarly, if the size of the key space reaches 2.64 , it takes more than 6 months, and with a key space of ^ 128 بیش more than 90 trillion centuries, it takes Javad to try all the possible keys with his computer.

So we need to make a change to the simple replacement encryption method to make the key space large enough. To do this, we change the way letters are substituted so that each letter can replace any other letter.

This means that we can have 26 choices to choose which letter to use instead of the letter a,

and then we will have 25 choices to choose the successor to the letter b (obviously we can not choose the letter that replaces the letter a) And so to select the 26 key! That means we have about 2.88 options.

This key space is large enough that Javad can not find the cryptographic key by trying all the keys. The following figure is an example of a key in this encryption method.

Cryptanalysis

We said that cryptanalysis or Cryptanalysis of cracking. Now we want to see with a simple example what it is like to break a cryptographic method. Suppose Javad succeeds in listening to this message:

Given that the cryptographic key can be any permutation of English letters, it is not possible for Javad to try all possible keys. So he has to use a smarter way to get to the content of the message.

The following is a graph of the frequency of letters in English.

And this figure is a diagram of the frequency of letters in the message that Javad overheard.

Looking at these messages and diagrams, one can guess that the letter F is used in the encrypted message instead of the letter e.

The first word is usually easier to guess than any other word.

Looking at the diagrams and knowing that the third letter was actually e instead of F, one can guess that the first word in the main message was the.

With this assumption in mind, the other two letters of the message are identified and can be used to find the next letters.

Something like solving a table.

Finally,

by continuing the same method, Javad can decrypt the message or make the remaining part of the key so small that it is possible to get the right key by trial and error.

So large key space, although necessary to have a secure encryption method, is not enough. How do we ensure a cryptographic method is secure?

What is meant by safe Cryptography?

If we can have a mathematical proof that it is not possible to get from encrypted text to plain text without a key,

we can be sure that the cryptographic method we use is secure. But such proof usually does not exist.

No such proof has been provided for any of the most widely used cryptographic methods.

In the absence of a mathematical proof of cryptographic system security,

if the best known attack on a cryptographic method is not computationally possible, we can consider that cryptographic system to be reliable.

In the series of articles where the term secure ( Secure ) encryption system used for an attack,

we mean is best known for its encryption system nearly as comprehensive search key ( Exhaustive key search ) requires time and computing power.

 

 

In a previous article from the Introduction to Information Security Fundamentals series , we learned the basic definitions of cryptography.

Do you remember that Morteza wanted to send a message to Jafar Bank, but because Javad might have overheard Pabamha, he had to use an encryption method to send his message in encrypted form.

To do this , we reviewed the surrogate encryption method and saw how this encryption could be broken using encryption analysis methods.

 In this article, we describe One Time Pad encryption. A cryptographic method that has been proven to be secure.

Morteza, who recently worked as a spy in Nazi Germany, wants to send an encrypted message to Jafar, who is in charge of his superior. He wants to use One Time Pad encryption to encrypt his message. Javad, a spy for the Soviet Union, also intends to eavesdrop on the message and crack the code.

To make our job easier, we consider only the first part of Morteza’s message. This message starts with the phrase heilhitler. To use One Time Pad encryption, we assign a binary code to each letter of the code.

Because in this example we are dealing with only 8 letters of the alphabet, we can assign a 3-bit code to each letter as follows.

These codes provide only a mapping of the alphabet to three-bit strings and should not be kept confidential. Using them here is something like using ASCII encoding.

In the previous article, we said that in a cryptographic method, there should be nothing secret other than the cryptographic key. We introduced this issue as the Karkhoff principle .

In this way, Morteza’s message (heilhitler phrase) becomes the following bit string:

How does One Time Pad encryption work?

Now Morteza has to encrypt his message using One Time Pad encryption. To do this, we need a key that is exactly the same length as the message. This key must be selected randomly. Morteza uses the following bit string as a key:

In the One Time Pad encryption method, to generate encrypted text or Cipher Text, we plain text with the XOR encryption key. One of the features of XOR operation is that:

a XOR b XOR b = a

For this reason, if the encrypted text (Cipher Text) is entered with the XOR encryption key, it will be the result of plain text operations. In this way, the encryption and decryption methods are exactly the same.

So Morteza’s message will be encrypted as follows:

Encrypted message means that the phrase srlhssthsr can be transmitted quite safely, without the listener of the message knowing anything about the content of the message.

The listener can only understand the length of the main message, but this problem can also be solved by using creative methods.

Jafar, who has the cryptographic key, repeats the same operation after receiving the message and obtains the main message.

If we decrypt the same encrypted text with another key, the simple message we get is completely different. Imagine using the following bit string as an encryption key to decrypt the srlhssthst message:

As you can see, the result is killhitler instead of heilhitler. Without knowing the key, any phrase with the same length can probably be exactly the same as the main message.

As a result, without knowing the key and holding the encrypted message, no guess can be made about the main message. This means that this encryption method is completely secure. But provided that each key is used only once.

Why is the One Time Pad encryption key disposable?

Suppose the two messages P1 and P2 are both encrypted with the K key.

C1 = P1 XOR K

C2 = P2 XOR K

C1 XOR C2 = P1 XOR K XOR P2 XOR K = P1 XOR P2

The above statement indicates that if the same cryptographic key is used twice, information about the original message can be found. In this case, it is enough to reveal only a part of one of the messages or guess correctly, so that the encryption is broken and more information about the main messages without a key is obtained.

For example, if both kite and like are both encrypted with a key:

The person listening to the messages can guess that the second and fourth letters of both messages are the same. Breaking the encryption by revealing the details of the messages can be as simple as solving the table.

Why can’t One Time Pad encryption be used for today’s applications?

We saw that the encryption key in the One Time Pad encryption method needs to be changed each time, and the length of this key should be the same size as the original message.

Choosing a key of this length is practically very challenging in today’s applications dealing with very large data, and transmitting a key of this size to any message is not safe to do.

Therefore, this method of cryptography, although it offers very good security, but can not be used in most applications today. But knowing this helps to understand the cryptographic methods used today.

Challenge your findings

At the end of the third article in the collection of information security basics,

it is not bad to review a little of what we have learned in these three articles.

If you are familiar with programming languages, you can implement successor cryptography or One Time Pad cryptography.

You can also think of creative ways to prevent message length from being revealed

in One Time Pad encryption and implement the way you think.

In the next article, we will look at the cryptographic methods used in the computer world today and learn how they work.