Cryptography is the science of securing information through encoding. It plays a fundamental role in cybersecurity, from encrypting messages to protecting passwords and verifying identities. This tutorial introduces the core principles and types of cryptography.
Step 1: What is Cryptography?
Cryptography transforms data into a form that only authorized parties can understand. It involves two main processes:
- Encryption: Turning plaintext into unreadable ciphertext.
- Decryption: Turning ciphertext back into plaintext using a key.
Step 2: Types of Cryptography
- Symmetric Encryption: Uses the same key for encryption and decryption.
Examples: AES, DES - Asymmetric Encryption: Uses a public key to encrypt and a private key to decrypt.
Examples: RSA, ECC - Hashing: Converts data into a fixed-size string, typically used for data integrity and password storage.
Examples: SHA-256, bcrypt
Step 3: Symmetric Encryption Example
// Pseudo-code
encrypted = aes_encrypt("message", key);
decrypted = aes_decrypt(encrypted, key);
Step 4: Asymmetric Encryption Example
// Pseudo-code
cipher = rsa_encrypt("secret", public_key);
plain = rsa_decrypt(cipher, private_key);
Step 5: Hashing Example
hash = sha256("mypassword");
Hashing is one-way; it cannot be reversed. Ideal for storing passwords.
Step 6: Real-World Use Cases
- HTTPS: Uses asymmetric encryption to exchange symmetric keys securely.
- Digital Signatures: Verify authenticity using private/public key pairs.
- JWTs: Use hashing and signing to verify the integrity of tokens.
Step 7: Best Practices
- Use strong, updated algorithms (e.g., AES-256, RSA 2048+).
- Never store encryption keys in your source code.
- Use secure libraries—don't build your own crypto!
Next Steps
Experiment with open-source libraries like OpenSSL or libsodium. Learn about key management, digital certificates, and hybrid encryption schemes for full-stack protection.