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Without modern cryptography techniques, the Internet as we know it would not exist. Secure communications enable virtually all online interaction. Encryption algorithms permit the secure exchange of data and confident verification of identity. Without these common cryptographic tools, our modern connected society could not function as it does today.

Symmetric Key Encryption Algorithms

Symmetric key encryption algorithms rely on a secure password to act as the key. This is the oldest form of encryption. Symmetric keys form the basis of everything from combination locks to modern hard drive encryption. AES, DES, and Blowfish are all modern symmetric key encryption algorithms.

Because symmetric encryption requires a shared key, the key exchange must be performed securely. While modern techniques like the Diffie-Hellmen key exchange permit exchanging a shared secret over insecure lines, it requires significant communication overhead to do so as well as shared trust between communications. If a shared key cannot be exchanged securely, communication cannot be conducted.

While symmetric key encryption is used in online communications, it is almost always paired with public key encryption, allowing for secure communication over open channels.

Asymmetric Key (Public Key) Encryption Algorithms

Asymmetric or public key encryption uses a pair of cryptographic keys. These keys relate to each other mathematically. The public key, shared widely, encrypts the message. The private key decrypts the message. As a result, any sender can encrypt a message with a recipient’s public key. Then they can be confident that only the intended recipient can decrypt the message because parties share no secret; they need no trust.

As a practical example, consider this analogy. What if Alice wants to communicate securely with Bob, but she doesn’t trust him?

Alice purchases a padlock and key combination. She unlocks the padlock with her key and sends the unlocked padlock to Bob.

Bob places his message in a box and uses Alice’s padlock to lock it.

Bob returns the locked box to Alice, secured with Alice’s padlock.

Alice opens the box with the padlock’s key, which only she possesses.

For ease of communication, Alice can duplicate the unlocked padlock and publish it widely. Anyone with the padlock can send her secure communications. With a sufficiently complex lock, an attacker cannot derive the key from the lock alone.

Security in (big) numbers

To remain secure, these algorithms rely on complex padlock/mathematical problems with no known efficient solution. These intractable problems define one-way functions: easy to compute in one direction but extremely difficult to compute backward. RSA, a commonly-used public key algorithm, relies on the difficulty in finding prime factors of integers with hundreds of decimal digits.

To start, an RSA user generates two very large prime numbers. These numbers are then multiplied together to create the product. The user keeps the prime factors which comprise the private key, a secret. The user publishes a public key derived from the product of the prime pair. The public key encrypts messages; the private key decrypts them.

Without knowing the prime factors, finding the prime factors of the product would take an infeasible amount of time. RSA-1024, the minimum standard, uses 1024-bit binary products made from 512-bit binary primes. According to the math, it would require 5.95 × 10^211 years to factor without the key. For perspective, the universe has only existed for a comparatively short 13.75 x 10^19 years.

Hash Functions

A hash function translates a message of arbitrary length to a fixed-length string called a hash or digest. Cryptographic hashes are deterministic: the same input always produces the same output. Even minor changes to the message will result in a dramatically different hash. Discovering two unique messages that produce the same hash value, called a hash collision, should be infeasible.

Digital signatures and password authentication both use hash functions like SHA. Rather than authenticating your plain text password, login servers use the hash of the password. The server compares this hash against the server’s stored hash. Same hash, same password.

Salted Hashes

For password storage, companies typically add a “salt” before hashing. This randomly-generated string is concatenated with the password text before hashing, ensuring that even two identical passwords produce distinct hashes. This also defends against a dictionary attack on a stolen table of hashed passwords.

Conclusion

Up until the 1970s, encryption relied on symmetric keys. Only after the proof of public key encryption could two different keys — one encrypting, one decrypting — be used to communicate. This revolutionary change, which allows for communication without trust, is what allows the Internet to exist in the form it takes today. Everything from banking and shopping to messaging and web browsing relies on it.

Alexander Fox

Alexander Fox is a tech and science writer based in Philadelphia, PA with one cat, three Macs and more USB cables than he could ever use.

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## Symmetric Encryption Cryptography In Java

Introduction

Symmetric encryption, also known as secret-key encryption, is a type of encryption where the same key is used for encryption and decryption. This encryption method is fast and efficient, making it suitable for encrypting large amounts of data. The most commonly used symmetric encryption algorithm is the Advanced Encryption Standard (AES).

Java provides strong support for symmetric encryption with the javax.crypto package, which includes classes such as SecretKey, Cipher, and KeyGenerator.

Symmetric Encryption in Java

Java’s Cipher class in the javax.crypto package provides the functionality of a cryptographic cipher for encryption and decryption. It forms the core of the Java Cryptographic Extension (JCE) framework.

In Java, the Cipher class provides the functionality for symmetric encryption, while the KeyGenerator class is used to generate secret keys for symmetric encryption.

Example

Let’s look at a simple implementation of symmetric encryption using AES in Java −

import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import java.nio.charset.StandardCharsets; import java.util.Base64; public class Main { public static void main(String[] args) throws Exception { SecretKey secretKey = KeyGenerator.getInstance("AES").generateKey(); String originalMessage = "Hello, world!"; Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, secretKey); byte[] encryptedMessage = cipher.doFinal(originalMessage.getBytes(StandardCharsets.UTF_8)); String encodedMessage = Base64.getEncoder().encodeToString(encryptedMessage); System.out.println("Original Message: " + originalMessage); System.out.println("Encrypted Message: " + encodedMessage); cipher.init(Cipher.DECRYPT_MODE, secretKey); byte[] decryptedMessage = cipher.doFinal(Base64.getDecoder().decode(encodedMessage)); System.out.println("Decrypted Message: " + new String(decryptedMessage, StandardCharsets.UTF_8)); } } Output

When you run the program, you’ll see output similar to the following −

Original Message: Hello, world! Encrypted Message: iWohhm/c89uBVaJ3j4YFkA== Decrypted Message: Hello, world! Explanation

In the code above, we first generate a secret key for AES encryption using the KeyGenerator class.

We then create an instance of the Cipher class for AES and initialize it to ENCRYPT_MODE with the secret key.

Next, we define an original message, “Hello, world!”, and encrypt it using the Cipher’s doFinal method. We also convert the encrypted message bytes to a Base64 encoded string to make it easier to handle.

We then print the original and encrypted messages to the console.

To demonstrate decryption, we reinitialize the Cipher to DECRYPT_MODE with the same secret key and decrypt the encrypted message. Finally, we print the decrypted message to the console.

The encrypted message will vary each time you run the program, due to the unique secret key generated each time.

The important thing to note here is that the decrypted message is identical to the original message, demonstrating that our encryption and decryption process is working correctly.

Points to Remember

Symmetric encryption is a powerful tool for maintaining confidentiality, but it’s important to remember that the security of your data depends on the security of your key. If an unauthorized person gains access to your secret key, they can decrypt your data. Therefore, it’s crucial to keep your secret keys secure.

Conclusion

Implementing symmetric encryption in Java is a straightforward process thanks to the javax.crypto package. Understanding how to use the Cipher and KeyGenerator classes to encrypt and decrypt data can provide a significant boost to the security of your Java applications.

## How Does Encryption Work?

Code

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Code

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z More alphabets and unbreakable encryption

The weaknesses of the Caesar substitution cipher can be slightly alleviated by using more than one shifted alphabet. The example below can be expanded to 26 shifted alphabets of which several are used at once, but not all of them.

Code

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Z A B C D E F G H I J K L M N O P Q R S T U V W X Y Y Z A B C D E F G H I J K L M N O P Q R S T U V W X X Y Z A B C D E F G H I J K L M N O P Q R S T U V W W X Y Z A B C D E F G H I J K L M N O P Q R S T U V

Code

I S T H I S U N B R E A K A B L E P S O V Y V U B M W S P A H Q T D

Rather than doing a straight substitution this time we use addition, with a twist. Each letter of the alphabet is assigned a number, A is 0, B is 1, C is 2 and so on. I is the 9th letter of the alphabet, which means it has a value of 8. P (the letter below it on our one-time-cipher pad) 15. 8 + 15 = 25 which means X. The second letter of our message is S, which has the value 18. It just so happens that S is also the letter on our one-time pad (which isn’t an issue at all). 18 + 18 = 36. Now here is the twist, there is no 36th letter of the alphabet. So we perform what is called a modulus operation. What that basically means is that we divided the result by 26 (the number of letters in the alphabet) and use the remainder. 36 / 26 = 1 remainder 10. The letter with the value of 10 is K. If you continue doing this the final encrypted message is:

Computers are flexible, unlike mechanical boxes, computers can be programmed to perform lots of different operations on a message and the number and complexity of these operations can be altered relatively quickly.

Speed.

Computers deal with binary numbers not just letters.

Exclusive OR (XOR) – This is a bit level logical operation that is applied to 2 input bits A and B. The Exclusive OR returns true or false (1 or 0) to the question, “A or B, but not, A and B”. You can think of it as, “one or the other but not both”. So, if A is 1 and B is 0 then that is one or the other, so the result is 1 (true). The same result applies to A is 0 and B is 1. But if A is 0 and B is 0 then the result is 0 (false), as both have the same value. False is also given for A is 1 and B is 1.

But the real magic of XOR is that it is reversible. If A XOR B = C then B XOR C = A, and A XOR C = B. This is very important for encryption as it means that data can be encrypted (where A is the data) using a key (B) to get the encrypted data (C). Later the encrypted data can be decrypted by XOR it with the key again to get the original data. The reason XOR is used in conjunction with complicated round functions and bit shifting operations is because on its own XOR can be broken using frequency analysis (because of the constantly repeating key).

Public key cryptography and wrap-up

## How Does Prolog Programming Work?

Introduction to Prolog Programming

Web development, programming languages, Software testing & others

Why we need Prolog programming?

It is a first-order logic programming language.

The programmer does not require complex algorithms and coding.

this programming is easier for Pattern matching and searching data than in other programming languages.

It works with abstract models and deals with objects.

This programming is the prolog is an easy, simple, and formula-based programming language.

This programming separates logics and controls of the data.

The prologs are based on the symbolic and computation for manipulation.

It is based on numerical data for pattern matching.

This programming language is a relational database for maintaining a memory management system.

It provides small syntaxes and small coding patterns.

It is based on the searching tree of determination and possibility.

The prolog supports a lot of the extensions like socket interface, global variables, and operating system interfaces.

It supports the native code compiler and becomes a stand-alone programming language.

The prolog supports constraints like arithmetic, Boolean, symbolic, etc.

This programming provides an efficient constraint solver and makes compatibility with integrals and variables.

The prolog supports compiled predicates and consulted predicates in the compiler.

This programming supports powerful interfaces between the prolog and C programming language.

How does Prolog programming works?

The following shows the prologue programming’s working environment.

The downloaded software saves in the exe file format to install the software.

The working procedure of the prolog programming shows below.

The warren abstract machine (WAM) is working as a compiler for prolog language.

The compiler file is converted into independent low-level machine language.

The resulting file again translates into the target machine.

This working procedure makes a stand-alone programming language.

Advanced prolog programming requires constraints for problem-solving.

You choose arithmetic constraints, Boolean constraints, and symbolic constraints, and so on.

The basic procedure of this programming is shown below.

The prolog software creates a file with the chúng tôi format. The “*.pl” is an extension of the prolog file.

Write the syntax of the prolog programming language. You can use many entities in single relation.

It shows the basic syntax below.

Format –

relation (objects or data). relation (data1, data2, data).

The prolog programming example shows the basic output.

Example-

Example-

The Prolog programming software is easy to build and install the software.

This programming language does not need lengthy syntax and coding.

This compiler is working fast and hustle-free.

It has powerful interfaces between the prolog and C programming language.

The user of prolog programmer creates their constraints with customization.

The prolog programmer provides several extensions.

This programming language provides high-level and categorized constraints.

The prolog supports easier pattern matching and searching data features.

The prolog language does not use complex algorithms and coding.

This language maintains and operates data lists with easy coding.

The several algorithm and code for input and output procedures are not easy.

The LISP language dominates and overcomes input and output features.

It does not support graphics features. If you need graphics, then you must use turbo prolog.

The prolog order affects the efficiency of the programming language.

This language does not support the “OR” logical conditions. This language does not support multiple true statements.

This language does not support the “NOT” logical condition. This language does not support negative statements.

The prolog is first-order logic language. This language does not allow second-order logic directly.

Uses

It is mostly usable in artificial intelligence technology.

This programming language uses for pattern matching using the parse tree feature.

The prolog is used in the computation schematics.

This programming uses in the problem-solving and understanding of natural language.

This language uses planning and designing of the robot.

The prolog is used in the automation system and theorem proving with a variety of constraints.

The prolog is a useful language in machine learning and the graphical user interface.

This is used for expert system and term rewriting using arithmetic and symbolic constraints.

Conclusion

It is simple planning and problem-solving programming language.

This language is used for AI, machine learning, and computational technology.

The prolog works in large-size applications in small and easy coding.

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## How Does Wireless Charging Work?

Wireless charging lets you charge up your gadgets without having to plug in a USB cable. It’s pretty neat, but how does it actually work? Why even bother? What are the downsides?

We’ll tackle everything you need to know about how wireless charging works right here. Soon you’ll forget what all that wire clutter was like!

A Matter Of Induction, My Dear Watt(son)

Generally, wireless chargers use a property of magnetism and electricity known as “induction” charging. Basically, electric current is converted into a magnetic field. This field then induces an electric current in the device you want to charge.

That’s a bit of an oversimplification, but it’s essentially what happens in the wireless charging process. There are two coils, one in each device, that convert the energy from one form to another.

This is the most common form of wireless charging you’re likely to find in personal gadgets such as smartphones or smart watches. Induction charging only works over very short distances. Usually 10mm or less. So although the power is “wireless” you usually need to set the device down on some sort of charging pad for the power to flow. Induction chargers such as these use low frequency signals to move power from the charger to the device.

The Resonant Alternative

It’s a futuristic idea, but electrical pioneer Nikola Tesla was doing it more than a century ago. Had history gone in a slightly different direction, wireless electricity might have been the standard way of doing things today.

A Two-Horse Race

There are different approaches to how wireless charging works, each with their own pros and cons. Different companies have different visions as to how we all want to use wireless power in daily life. This has given rise to multiple standards for wireless charging and, as you’ve probably guessed, these standards don’t inter-operate.

Qi wireless chargers use the short-range induction method and this is what you’ll find in most personal devices that charge wirelessly.

The AirFuel standard uses the long-range resonant method and you’re not likely to find it built into your gadgets quite yet. However, you can buy special charging cases for smartphones that add AirFuel capability to them.

Faster! Faster!

One thing you may notice about wireless charging, regardless of the standard, is that they don’t offer that much power. Fast-charging has become pretty much the standard when using a cable. Modern USB-C smartphones and laptops can often accept anything between 40 and 60 watts. Using USB-C Power Delivery, you can actually move 100W of power over a USB-C cable, but not current lithium ion batteries in a phone can accept that.

Qi or AirFuel chargers don’t offer nearly as much power, but both standards are evolving. At the time of writing, 40W wireless fast charging has started to enter the market and AirFuel hopes to reach 100W at some point in the future. We can also expect battery technology to improve, making it easier to charge devices more quickly.

However, as of right now, one major downside of wireless charging is that it’s slower than using a direct wire connection and it can’t actively power devices that need even a moderate amount of power to work.

One Charger To Rule Them All

So anyone with a Qi device can simply put it on your pad and charge up. That’s cool, but the real killer feature is the ability to charge multiple devices on the same charging pad at the same time. You need a charger with one coil for each device you want to charge.

For example, “triple chargers” have three coils and therefore three charging spots. You can put three devices next to each other and have them charge at the same time. That can be a pretty elegant solution. For example, if you place a triple charger on a side table in your living room, it’s a central place where people can put their devices.

Devices That Only Charge Wirelessly

Most devices that charge wirelessly, such as smartphones, also give you the option of wired charging. However, there are some devices that only let you charge them wirelessly. Smartwatches are one example of this and when you think about it, it makes sense.

If you want to create a device that’s truly dust and waterproof, having a bunch of ports can be a pain. Not to mention that small devices such as wireless buds or smartwatches often don’t have space for standard connectors anyway.

How does wireless charging work on larger devices? While there are as yet no phones, tablets or laptops that we are aware of with exclusive wireless charging don’t assume it will never happen. A completely sealed device that uses only wireless communication and charging would open up new doors when it comes to ruggedization and design.

Phones & Power Banks That Provide Wireless Charging

Wireless chargers themselves have gone wireless in the sense that you can now get power banks and even smartphones that can charge devices wirelessly using the Qi standard.

Smartphones such as the Note 10+ have a feature known as “Wireless Powershare” and it’s very handy for charging devices such as wireless earbuds or smartwatches. Wireless power banks are of course also useful for that use case, but it also brings up the interesting possibility of sticking your phone to the power bank and temporarily using it as one cable-free hunk.

A Wireless Future

Short-range Qi induction charging is certainly here to stay, but we’ve seen some impressive demonstrations of long range charging using the resonance method. Fitting an LCD TV with a receiver coil, simply bringing it within range of another coil installed within a wall will power it on.

With both power and data transfer possible wirelessly, there are new avenues product designers can take. We might be heading for an interesting future of devices that always have power, don’t need to be opened and in some cases may no longer need batteries to operate.

Of course, it will be some time until long range wireless power becomes the norm. You can certainly expect quite a bit of pushback as well. There’s already plenty of (usually unwarranted) concerns about electromagnetic radiation technologies such as 5G causing health issues or environmental problems. We expect the same sorts of complaints to arise when long-range wireless power transmission becomes more common.

## How To Login In Lightroom + Fix Common Sign

You go to open up Lightroom or Lightroom Mobile, and suddenly you’re prompted to log in to your account again… for the one-hundredth time in a row. As you sigh in frustration, knowing you’ve had to sign in every time you used the app, it dawns on you that maybe, just maybe, it doesn’t have to be this way. With the help of a few easy tips, you can log in to Lightroom quickly without having to ever do it again. Here’s how.

Now, you may face a few different situations depending on whether you’re logging into Lightroom or Lightroom Mobile. This post will break down everything you should know to help guide you through the sign-in process and troubleshoot any problems you have.

To log in to Adobe Lightroom on your desktop, start by opening the app on your computer. If you are not already signed in, a prompt will appear asking you to do so before you continue. Since Lightroom is a subscription-based app, you cannot use it until your account details and subscription are confirmed.

For example, if your Creative Cloud subscription is linked to your Adobe ID, signing in with Facebook will create a totally new account. More specifically, an account without any of your subscription details. That’s why it’s important to choose the right sign-in option!

Once you have entered your email and password, your account will be confirmed, and you’ll have immediate access to Lightroom. If this is your first time logging in, you won’t see any images appear since you have yet to import them. If you are a long-time user and your Lightroom login got signed out accidentally, all your imported photos will appear just as they were before!

Now you can begin editing your images and make the most of Lightroom once you’ve logged in!

How To Login In Lightroom Mobile

If you already use Lightroom on your desktop computer, you must sign into the same account. This will ensure your subscription details and any cloud-stored photos will sync between your mobile and desktop apps. If you aren’t sure which login option to choose, take a look at your desktop Lightroom to view which account is signed in.

With that said, if you are not a paid Creative Cloud subscriber, this step will not matter as you’ll only have the free account. There are many perks to upgrading to the paid version of LR Mobile, but the app still works well at the free level.

Now that you are logged in, you have access to Lightroom Mobile and all the tools inside!

Can You Use Lightroom Without Signing In?

You cannot use Lightroom without first signing in to your Adobe CC account. Since Lightroom is part of a subscription model, your account and subscription details must be linked before use. Luckily with the Creative Cloud App, you can log in once to sync between all apps in your subscription.

So if you are trying to get through to Lightroom desktop for free, you’re going to be out of luck. However, Lightroom Mobile is completely free but requires you have an account created before use. This app is a great option if you want to edit photos without the cost.

Now, like I just mentioned, the Creative Cloud App allows you to log in to your account once, and that login will apply to all the installed apps on your computer.

Here’s how it works:

Now that you’re logged in, you can see all of the apps you currently have downloaded, along with the ones available for download. Depending on your subscription plan, the programs available to you will vary.

Once installed, you can open Lightroom on your computer, and it will automatically connect to the Creative Cloud app to confirm your login details. Since you’ve signed into the Creative Cloud app already, Lightroom will open without needing to sign in. This same thing applies to all of the Adobe CC apps installed on your device.

The beauty of the Creative Cloud app is that even if your computer restarts, you’ll remain signed in to Lightroom. That way, you never have to sign in again, after the initial set up of course!

How To Skip Login In Lightroom

After you’ve successfully logged in to the app, it will ask you to allow notifications on your device. Make sure to choose “Allow”; otherwise, you will not get any prompt when trying to log in from another device.

Besides that, the interface is quite simple. Your name and account details are listed, along with a verification code that changes every 30 seconds. When you attempt to log in from another device, all you need to do is type in the email for your account. Adobe Account Access will immediately open up with a prompt asking you to match the number shown on your screen.

In this example, the number on my computer was 0, so I pressed 0 in the Account Access app. This confirms my login instantly without ever needing to type in my password!

If you find that you sign in between multiple devices frequently, this app is a huge help to avoid typing in your password every time.

How To Fix Common Login Problems In Lightroom

Now that you know the basics of how to log in to Lightroom, you may face a few issues along the way. If you’re having issues, try these 6 solutions listed by the related problem.

1. I Get Signed Out Of Lightroom Each Time I Restart The Computer

If you find that you constantly get signed out of Lightroom when you restart your computer, it’s likely due to not having the Creative Cloud app installed on your computer. With this app, you can stay signed in to your Adobe account, allowing you to use all the apps in your plan with ease.

To streamline the process further, turn on the stay signed in option.

This will take you to your account page on the Adobe website and let you know which subscription plan you are a part of. If you are on a free trial, it will let you know when the trial expires via this window. To keep you signed in to Lightroom, you’ll need to have a paid Adobe CC subscription such as the Photography Plan.

With everything in order, the Creative Cloud App will remember your login details and keep you signed in all the time. This way, you never have to log in to Lightroom in the future since it automatically connects to your account.

If you forget your Adobe ID or what email you used for your plan, there are a couple of easy ways to resolve this.

If you’re like me, you may have multiple emails that you could have used. The easiest way to figure out which one is being used for Adobe is to go to your email and search for “Adobe” or “Creative Cloud.” If your email displays past emails from Adobe regarding your CC subscription, then that’s the email you use for your account!

3. My Lightroom Desktop & Lightroom Mobile Apps Aren’t Syncing

With Adobe Lightroom and Lightroom Mobile, you can sync your libraries to work seamlessly between two devices. However, there are a few caveats to this.

– Ensure Syncing Is Enabled

It’s worth remembering that this is only possible between Adobe Lightroom and Lightroom Mobile. Adobe Lightroom Classic does not work with cloud-based syncing options.

– Double Check You’re Logged In With The Same Account

– Make Sure You Haven’t Exceeded The Cloud Storage Limits

If all else fails, double-check that you actually have cloud storage available to use. Depending on your plan, you may have filled all of the cloud storage, making it impossible for new photos to sync. You can double-check how much available space there is in both Lightroom desktop and mobile.

If this progress bar is full, that means you have no cloud storage left, and new images will not sync. You can solve this issue by deleting unused photos or purchasing more cloud storage space.

4. My Account Gets Logged Out When I Exit Lightroom

The easiest way to avoid this issue is by installing the free Creative Cloud App that keeps you signed in between all apps. However, you can also turn on the “stay signed in” option when you log in to Lightroom to ensure your account details are remembered.

5. I Forgot My Password For Lightroom

First, go to the Adobe Help Center.