What is cryptography?
Cryptography is the art and science of turning information into a secret code so that only the intended people can read it. It uses math and computer algorithms to scramble (encrypt) data and then unscramble (decrypt) it when needed.
Let's break it down
- Plaintext: the original, readable information.
- Ciphertext: the scrambled version that looks like random gibberish.
- Encryption: the process of converting plaintext into ciphertext using a key.
- Decryption: the reverse process, turning ciphertext back into plaintext with the same (or a related) key.
- Key: a secret piece of data (like a password) that tells the algorithm how to scramble and unscramble the information.
- Algorithm: the step‑by‑step recipe that uses the key to encrypt or decrypt data (examples: AES, RSA, SHA).
Why does it matter?
Cryptography protects privacy, keeps online transactions safe, and prevents hackers from stealing or altering data. Without it, anyone could read your emails, see your credit‑card numbers, or impersonate you online.
Where is it used?
- Secure websites (HTTPS)
- Messaging apps (WhatsApp, Signal)
- Online banking and credit‑card payments
- Password storage (hashing)
- Virtual private networks (VPNs)
- Digital signatures for software updates and documents
Good things about it
- Provides confidentiality, integrity, and authentication.
- Enables trust in e‑commerce and online services.
- Allows secure communication even over insecure networks.
- Supports modern technologies like blockchain and cloud security.
Not-so-good things
- Complex to implement correctly; mistakes can create vulnerabilities.
- Strong encryption can be misused by criminals to hide illegal activity.
- Requires careful key management; lost keys mean lost data.
- Some algorithms become obsolete as computing power grows (e.g., quantum computers may break current encryption).