One-Time Pad Cipher (Vernam)

Security Tools

Encrypt or decrypt text with a one-time pad key

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Add a file · .txt .md .csv .json … · up to 2.00 MB

Add a file · .txt .md .csv .json … · up to 2.00 MB

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History

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One-Time Pad Cipher (Vernam) — at a glance

Use the classic unbreakable cipher, with a random key made on your device.

Message + key

HELLO

XMCKL

Encrypt

Cipher

EQNVZ

How to use it — step by step

A message, plus a key of random letters at least as long as the message.

1

Paste your input

Paste or type your content into the big input box.

2

Run Cipher

Press the button. The result is created instantly on your device.

3

Copy the result

Check the output and press Copy to use it anywhere.

Pro tips

Small things that make the result better.

✦Never reuse a key. Reusing it breaks the security completely.

✦Share the key with your friend in person, not on the same channel as the message.

✦Spaces and punctuation are kept as they are and do not use up key letters.

Quick facts

Freeno signup, no limit

Instantresult in a moment

Privatenothing is uploaded

Any devicephone, tablet or PC

Frequently Asked Questions

Is it really unbreakable?+

Only if the key is truly random, as long as the message, kept secret and used once.

Is the random key safe?+

Yes. It uses your browser’s secure random number generator and is never sent anywhere.

Is my data safe?+

Yes. Everything runs inside your own browser. Your text, files and images are never uploaded to any server.

Is this tool really free?+

Yes — completely free, no signup, no watermark and no usage limit.

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