Encryption

Introduction

In the realm of computer science and programming, encryption plays a crucial role in safeguarding sensitive information. It involves the process of encoding data, known as plaintext, into an unreadable form called ciphertext. By utilizing encryption algorithms and encryption keys, only authorized parties can decipher the ciphertext and access the original information. In this article, we will delve into the concept of encryption, its historical significance, modern encryption techniques, and the role it plays in ensuring data security.

Understanding Encryption

Encryption is a cryptographic technique that transforms plaintext into ciphertext, making it unintelligible to unauthorized users. It provides a layer of protection against unauthorized access and ensures data confidentiality. The encryption process uses an encryption key, generated through a pseudo-random algorithm, to convert the plaintext into ciphertext.

Types of Encryption Techniques

Symmetric-Key Encryption:

In symmetric-key encryption, the same key is used for both encryption and decryption. The key must be kept secret and shared securely between the sender and the intended recipient. Algorithms like the Advanced Encryption Standard (AES) are commonly used in symmetric-key encryption.
Example (C#):

Public-Key Encryption:

Public-key encryption, also known as asymmetric encryption, uses a pair of keys – a public key for encryption and a private key for decryption. The public key is freely distributed, allowing anyone to encrypt data, while the private key remains secret and is used for decryption. The RSA algorithm is a popular choice for public-key encryption.
Example (JavaScript):

Example (Python):

Hybrid Encryption:

Hybrid encryption combines the strengths of both symmetric-key and public-key encryption. In this approach, the data is encrypted using a symmetric-key algorithm, and the symmetric key is then encrypted using the recipient's public key. This ensures secure transmission of the symmetric key, which is then used for decryption.
Example (PHP):

The Significance of Encryption

Encryption plays a vital role in protecting sensitive data in various fields, including financial transactions, secure communication, and data storage. It ensures that even if an unauthorized individual gains access to the encrypted data, they cannot decipher it without the encryption key. Moreover, encryption also helps in maintaining data integrity, as any modifications made to the ciphertext will render it unreadable.

Links

Code Examples

C#
using System;
using System.Security.Cryptography;
using System.Text;

public static string Encrypt(string plainText, string key)
{
    byte[] encryptedBytes;
    using (Aes aes = Aes.Create())
    {
        aes.Key = Encoding.UTF8.GetBytes(key);
        aes.Mode = CipherMode.ECB;
        aes.Padding = PaddingMode.PKCS7;

        ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV);
        byte[] plainBytes = Encoding.UTF8.GetBytes(plainText);

        encryptedBytes = encryptor.TransformFinalBlock(plainBytes, 0, plainBytes.Length);
    }

    return Convert.ToBase64String(encryptedBytes);
}

JavaScript
const crypto = require('crypto');

function encrypt(plainText, publicKey) {
    const encryptedBuffer = crypto.publicEncrypt(publicKey, Buffer.from(plainText));
    return encryptedBuffer.toString('base64');
}

Python
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives.asymmetric import padding

def encrypt(plain_text, public_key):
    public_key = serialization.load_pem_public_key(
        public_key.encode(),
        backend=default_backend()
    )
    encrypted_data = public_key.encrypt(
        plain_text.encode(),
        padding.OAEP(
            mgf=padding.MGF1(algorithm=hashes.SHA256()),
            algorithm=hashes.SHA256(),
            label=None
        )
    )
    return encrypted_data.hex()

PHP
function encrypt($plainText, $key) {
    $ivlen = openssl_cipher_iv_length($cipher="AES-128-CBC");
    $iv = openssl_random_pseudo_bytes($ivlen);
    $ciphertext_raw = openssl_encrypt($plainText, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);
    $hmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);
    $encrypted = base64_encode($iv.$hmac.$ciphertext_raw);
    return $encrypted;
}

Conclusion