What does ROT13 Brute Force search?

It enumerates meaningful rotation amounts for the ROT13 transformation. It does not search all cipher families or identify arbitrary encrypted data. Review candidate rows against the source clue.

How do Sample length and Sample offset affect results?

These controls choose the part of the input used for candidate output. A short sample can omit the useful part of a message. Record the offset and test the full relevant text before deciding.

What should I enter as a crib?

Enter text that you expect in the original message. The crib filters candidate results rather than proving the scheme is correct. A missing result can mean a wrong crib, unsuitable sample, or a different cipher.

Brute Force for ROT13 Cipher Processor

Tool workspace

Your input stays in this browser.

Needs input

You can run the tool again after any change.

Input

Options

Rotate lower case chars

Rotate upper case chars

Rotate numbers

Sample length

Sample offset

Print amount

Crib (known plaintext string)

Your result appears here

Apply ROT13 Brute Force with explicit key, format, and algorithm settings. Enter the data and key material, choose the parameters, then review the result.

This tool runs open-source code from CyberChef by GCHQ (Apache License 2.0). See open-source credits.

Brute Force for ROT13 Cipher Processor uses alphabet rotation search to process the supplied input. It lists candidate rotations whose text contains the case-insensitive crib. Amount 23 produces HELLO for the fixture.

It lists candidate rotations whose text contains the case-insensitive crib. Amount 23 produces HELLO for the fixture. Processing runs in the browser for this catalog category, so the result depends on the supplied bytes and settings. Processing runs in the browser.

Cipher search explores the configured space; it does not bypass strong encryption or establish evidence authenticity.

Instructions

Provide text or data for this tool.
Set the crib empty to inspect all candidates. This applies to Brute Force for ROT13 Cipher Processor.
Increase Sample length when the required text falls outside the selected slice. This applies to Brute Force for ROT13 Cipher Processor.

Example

Input: Use "KHOOR", rotate uppercase enabled, Sample length 100, offset 0, and Crib "HELLO".

Settings: Brute Force for ROT13 Cipher Processor: Enable lowercase, uppercase, and numeric rotation independently. Print amount labels the tested rotation; the search tries amounts 1 through 25.

Result: It lists candidate rotations whose text contains the case-insensitive crib. Amount 23 produces HELLO for the fixture. Processing runs in the browser for this catalog category, so the result depends on the supplied bytes and settings.

Limits

Brute Force for ROT13 Cipher Processor: The search omits the unchanged zero rotation.
Brute Force for ROT13 Cipher Processor: A matching crib can occur by chance and does not establish the original message.