VIGENÈRE CIPHER
Vigenère cipher, a polyalphabetic lock.
Enter text and a key to encrypt or decrypt. The key cycles over the plaintext, harder to crack than a simple Caesar — a CTF staple.
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What is this?
Vigenère uses a repeating sequence of Caesar shifts: each plaintext letter is shifted by the position of the matching key letter. Decryption subtracts. Only A–Z/a–z are shifted; others are kept.
FAQ
Can the key be Chinese?
Standard Vigenère uses A–Z only. Non-letters in the key are ignored and letters are uppercased before use.
Is anything uploaded?
No. Everything runs in your browser; nothing is sent to a server.
示例与注意事项Example & notes
一个例子A worked example
明文 ATTACK、密钥 KEY 加密得到 KXRKCE——每个字母的位移量都不同，比凯撒难破解得多。Plaintext ATTACK with key KEY encrypts to KXRKCE — each letter shifts by a different amount.
注意事项Things to watch
- 密钥循环使用，太短会暴露周期性，建议与明文长度相当。The key repeats, so a short one exposes periodicity; match the message length.
- 同一明文配不同密钥结果完全不同，这正是它的价值。The same plaintext with a different key gives unrelated output — that is the point.
- 仍属古典密码，现代场景请使用 AES 等标准算法。It is still classical crypto; use AES or similar for real work.
相关问答More Q&A
怎么解密？How do I decrypt?
用同一密钥反向位移即可，页面支持加密与解密双向切换。Shift backwards with the same key — the page toggles between the two directions.
密钥可以用中文吗？Can the key be Chinese?
建议用字母；中文可先转拼音再作为密钥。Stick to letters; convert Chinese to pinyin first.