Encryption in C#

What is Encryption?

Encryption is a way of scrambling data so that only authorized parties can understand the information. In technical terms, it is the process of converting human-readable plaintext to incomprehensible text, also known as ciphertext. In simpler terms, encryption takes readable data and alters it so that it appears random. Encryption requires the use of a cryptographic key: a set of mathematical values that both the sender and the recipient of an encrypted message agree on.

Although encrypted data appears random, encryption happens in a logical, predictable way, allowing a party that receives the encrypted data and possesses the right key to decrypt the data, turning it back into plaintext. Truly secure encryption will use keys complex enough that a third party is highly unlikely to decrypt or break the ciphertext by brute force — in other words, by guessing the key.

Data can be encrypted "at rest," when it is stored, or "in transit," while it is being transmitted somewhere else.

What is a key in cryptography?

A cryptographic key is a string of characters used within an encryption algorithm for altering data so that it appears random. Like a physical key, it locks (encrypts) data so that only someone with the right key can unlock (decrypt) it.

 What are the different types of encryption?

There are two main kinds of encryption, these are symmetric encryption and asymmetric encryption. Asymmetric encryption is also known as public key encryption.

Symmetric Encryption

In symmetric encryption, there is only one key, and all communicating parties use the same (secret) key for both encryption and decryption.

In Symmetric-key, ciphers use the same secret key for encrypting and decrypting a message or file. While symmetric-key encryption is much faster than asymmetric encryption, the sender must exchange the encryption key with the recipient before he can decrypt it. As companies find themselves needing to securely distribute and manage huge quantities of keys, most data encryption services have adapted and use an asymmetric algorithm to exchange the secret key after using a symmetric algorithm to encrypt data.

Asymmetric Encryption

Asymmetric encryption, also known as public-key encryption, is a form of data encryption where the encryption key (also called the public key) and the corresponding decryption key (also called the private key) are different. A message encrypted with the public key can be decrypted only with the corresponding private key. Both the public and private keys are related mathematically, but it is computationally infeasible to derive the private key from the public key. Therefore, a recipient could distribute the public key widely. Anyone can use the public key to encrypt messages for the recipient and only the recipient can decrypt them.

In asymmetric, or public key, encryption, there are two keys: one key is used for encryption, and a different key is used for decryption. The decryption key is kept private (hence the "private key" name), while the encryption key is shared publicly, for anyone to use (hence the "public key" name). Asymmetric encryption is a foundational technology for TLS (often called SSL).

What is Cipher?

In cryptography, a cipher is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure.

 CHALLENGES TO CONTEMPORARY ENCRYPTION

The most basic method of attack on encryption today is brute force, or trying random keys until the right one is found. Of course, the length of the key determines the possible number of keys and affects the plausibility of this type of attack. It is important to keep in mind that encryption strength is directly proportional to key size, but as the key size increases so do the number of resources required to perform the computation.

Alternative methods of breaking a cipher include side-channel attacks and cryptanalysis. Side-channel attacks go after the implementation of the cipher, rather than the actual cipher itself. These attacks tend to succeed if there is an error in system design or execution. Likewise, cryptanalysis means finding a weakness in the cipher and exploiting it. Cryptanalysis is more likely to occur when there is a flaw in the cipher itself.

 What is an encryption algorithm?

An encryption algorithm is the method used to transform data into ciphertext. An algorithm will use the encryption key in order to alter the data in a predictable way, so that even though the encrypted data will appear random, it can be turned back into plaintext by using the decryption key.

What are some common encryption algorithms?

Commonly used symmetric encryption algorithms include:

AES

3-DES

SNOW

Commonly used asymmetric encryption algorithms include:

RSA

Elliptic curve cryptography

 What is a brute force attack in encryption?

A brute force attack is when an attacker who does not know the decryption key attempts to determine the key by making millions or billions of guesses. Brute force attacks are much faster with modern computers, which is why encryption has to be extremely strong and complex. Most modern encryption methods, coupled with high-quality passwords, are resistant to brute force attacks, although they may become vulnerable to such attacks in the future as computers become more and more powerful. Weak passwords are still susceptible to brute force attacks.

 How is encryption used to keep Internet browsing secure?

Encryption is foundational for a variety of technologies, but it is especially important for keeping HTTP requests and responses secure, and for authenticating website origin servers. The protocol responsible for this is called HTTPS (Hypertext Transfer Protocol Secure). A website served over HTTPS instead of HTTP will have a URL that begins with https:// instead of http://, usually represented by a secured lock in the address bar.

HTTPS uses the encryption protocol called Transport Layer Security (TLS). In the past, an earlier encryption protocol called Secure Sockets Layer (SSL) was the standard, but TLS has replaced SSL. A website that implements HTTPS will have a TLS certificate installed on its origin server.

 Thank you

 References

1.     https://www.cloudflare.com/learning/ssl/what-is-encryption/ accessed on 25/01/2021

2.   https://www.cloudflare.com/learning/ssl/how-does-public-key-encryption-work/ accessed on 25/01/2021

3.     https://blog.keyfactor.com/symmetric-vs-asymmetric-encryption accessed on 25/01/2021