RSA encryption is a cryptographic algorithm that’s used for secure communication. It’s based on the fact that it’s really hard to calculate the product of two large prime numbers. This is because finding the prime factors of a large number is extremely difficult.If you have two different prime numbers, p and q, they can be multiplied together to create a public key and a private key. The public key would be (p * q) and the private key would be (p-1 * q-1). The message encrypted with this private key can only be decrypted by someone who has the corresponding public key. So if you send an email encryped with the public key to your friend, they can use their private key to decrypt it. If a third party tries to read the email, they will not be able to decrypt it. This is because finding the prime factors of a large number is extremely difficult.
The public key can be shared with anyone who wants to send you an encrypted message, and your private key must remain secret. This system has many applications including encryption for credit card transactions on the internet. This is a simple example of how public key encryption works.
The security in this system is based on the size of the numbers used, and the sparseness of prime numbers. The larger the number, and the sparser the primes are, (i.e. less common), then more secure it will be.
Several years ago I worked in a team that was developing software for RSA Security Inc., to implement their version of public key encryption as an option on credit card transactions over the internet. A lot has changed since then, but I think it illustrates how this technology can be used to share information securely between two parties that have never met before – even if they do not share a common language or culture – which is what is happening with the Syrian refugees.
For this example, I am going to use a simplified version of RSA security’s public key encryption algorithm because it is easier to explain and understand than a real implementation. For that reason, I will only discuss encrypting data. Decryption requires the same steps in reverse, but is conceptually identical.
Here are the steps:
Generate two large prime numbers (p & q) as an encryption key (this step is called key generation). The larger these numbers are, the more secure your encrypted information will be. Find another number (x) such that x multiplied by p equals y multiplied by q; this number (x) is called an encryption exponent . Divide your plaintext message into blocks of data, and encrypt each block using the encryption exponent.
The first two steps are done in advance by someone who wants to send an encrypted message. In step 3, I’ll show you how to do these three steps for yourself (I’ll use Ruby for the code examples).
Step 1: Generating a key pair
To generate a key pair, we need to find two large prime numbers p and q. The larger these numbers are, the harder it will be for someone else to decrypt your data. These primes can be found either by sheer chance or through trial and error . Once we have our primes, we have our key pair! We don’t need them again until it’s time to decrypt the data that was encrypted with them.
Step 2: Encrypting the data
To encrypt a piece of data, we must pass it through an encryption function that takes a key and returns an encrypted message. The encryption function in our case is called block-cipher . It takes two arguments: the first is the plaintext string, and the second is the key. The output of this method will be a cipher text string that can only be decrypted if you have access to both the original plaintext string and its associated key.
Step 3: Decrypting the data
Decryption works in reverse from encryption; we pass our cipher text through another function called a decryption function which accepts two arguments—the first is the cipher text, and second being its associated key. The output of this function will be the plaintext string.
Step 4: Verify that it worked
After you decrypt your data, you should test to ensure that the decryption was successful. To do this, you can use Python’s built-in ” len() ” function to check whether the length of the outputted plaintext is equal to the length of your original data . If it is not, then something went wrong with either your encryption or decryption process and you should take a closer look at what went wrong.
If all goes well, then congratulations! You’ve just encrypted and decrypted your first piece of data using an asymmetric cipher!
In summary, symmetric ciphers are great because they’re fast and easy to use, but they’re also bad because they’re fast and easy to break. Asymmetric ciphers are slower and more complex than symmetric ones, but they’re also much more secure.
Symmetric ciphers can be used for encrypting bulk data, like a file or even an entire disk drive. However, asymmetric encryption is best suited for encrypting smaller pieces of data that need to be encrypted quickly with little overhead (e.g., a small piece of text), because asymmetric encryption algorithms tend to be slower and require more resources than their symmetric counterparts do.
If you have any questions about this post or need clarification on anything I wrote here, please feel free to leave a comment below.
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