Encoding is not encryption · ⁨인코딩은 암호화가 아닙니다⁩

A common mix-up

• People often say "encoded" when they mean "encrypted". They are not the same.
• Encoding changes the format of data so it can be stored or sent — it is not secret.
• Encryption changes data so that only someone with the key can read it — it is secret.

Base64 — a famous encoding

• Base64 rewrites bytes using 64 safe characters. It is used to put images or files inside text (like email).

import base64
secret = base64.b64encode(b"hello").decode()
print(secret)            # aGVsbG8=
print(base64.b64decode(secret).decode())   # back to hello

• Anyone can decode it — no key needed. So base64 hides nothing.

Why this matters for security

• If a website "protects" your password with base64, it is not protected at all.
• Real protection needs encryption (with a key) or hashing (one-way). Encoding is just a costume.

Try it

• Encode hello to base64 below. Then imagine decoding it — and remember it is not a secret.

Covers: foundation for IGCSE 2.3 / A-Level 17.1 (encryption).

Common mistakes

• Base64 is encoding — anyone can reverse it, so it gives no security.
• Encoding changes the format; encryption protects the content.