凱撒密碼編碼與解碼工具

使用凱撒密碼對文字進行編碼或解碼：按固定位移替換字母。

位移: 3

如何使用本工具

1
Type or paste your message into the text area.
2
Drag the Shift slider to pick a key from -25 to +25; the default is 3.
3
Read the transformed text in the gray output box, which updates instantly as you type or move the slider.
4
To decode a message, set the shift to the negative of the value used to encode it (for example, use -3 to undo a +3 shift).

凱撒密碼是已知最古老的加密方法之一，可追溯到西元前50年左右尤利烏斯·凱撒的軍事通訊。每個字母在字母表中按固定的位置數進行位移。由於只有25種可能的金鑰，它極易被破解，但作為講解密碼學基礎的工具卻非常出色。

Teaching cryptography basics in a classroom by letting students watch each letter shift in real time.
Solving or creating Caesar-cipher puzzles in escape rooms, ARGs, and CTF challenges.
Decoding ROT13 text from forums or email by setting the shift to 13 or -13.
Brute-forcing an unknown shift: scrub the slider through all 25 values until readable text appears.
Generating lightly obfuscated spoiler text or hint answers that readers must shift back to reveal.
Prototyping and debugging encode/decode logic before wiring up a stronger cipher in your own code.

位移13是什麼？▼

這就是ROT13，一種自逆的特殊情況：套用兩次即可還原出原始文字。