Cryptography Basics

What is Cryptography?

Cryptography is the practice of securing information by transforming it into a format that is unreadable for unauthorized users. This ensures confidentiality, integrity, and authenticity of the data.

Types of Cryptography

1. Symmetric Cryptography

In symmetric cryptography, the same key is used for both encryption and decryption. It is fast and efficient but requires secure key distribution.

2. Asymmetric Cryptography

Asymmetric cryptography uses a pair of keys: a public key for encryption and a private key for decryption. It enhances security but is slower than symmetric methods.

3. Hash Functions

Hash functions convert data into a fixed-size string of characters, which is typically a hash value. They are not reversible and are used for data integrity verification.

Encryption Process

Step-by-Step Process

1. Select an encryption algorithm (e.g., AES, RSA).
2. Generate a secure key.
3. Convert plaintext (the original message) into ciphertext (the encrypted message).
4. Transmit the ciphertext securely.
5. Use the decryption algorithm with the key to convert ciphertext back to plaintext.

Code Example: AES Encryption

import base64
from Crypto.Cipher import AES
from Crypto.Util.Padding import pad, unpad
from Crypto.Random import get_random_bytes

# Key must be either 16, 24, or 32 bytes long
key = get_random_bytes(16)
cipher = AES.new(key, AES.MODE_CBC)

# Encrypt
data = b"Secret Message"
ct_bytes = cipher.encrypt(pad(data, AES.block_size))
iv = base64.b64encode(cipher.iv).decode('utf-8')
ct = base64.b64encode(ct_bytes).decode('utf-8')

print(f"iv: {iv}")
print(f"ciphertext: {ct}")
                

Best Practices

• Use strong, unique keys for encryption.
• Regularly update your cryptographic algorithms.
• Implement multi-factor authentication.
• Keep software and libraries up to date.
• Educate users about phishing attacks and social engineering.

FAQ