ROT13 Function (LibreOffice Calc)

• Introduced: First release not established; documented by LibreOffice 3.3.
• Supported in: LibreOffice 26.8 Help and 26.8.1.1 registration; no retirement is established.
• Scope: Desktop Calc, English semicolon-separated formulas. Only ASCII letters are rotated by the inspected algorithm.
• Checked: October 14, 2026. Eight examples were independently reconstructed from the complete source method. No native LibreOffice execution is claimed.

ROT13 replaces each ASCII Latin letter with the letter thirteen positions farther through the alphabet, wrapping after Z or z. It preserves the case of those letters and leaves other characters unchanged in the inspected implementation. This is reversible obfuscation with no secret key; it does not protect confidential information. Function Help.

ROT13(Text)

Text is the single string to transform. The complete date-add-in method accepts a string and walks its UTF-16 code units. Only the explicit ASCII ranges a–z and A–Z are changed. The examples here are independently reconstructed from that method and were not run in LibreOffice.

These are independently calculated source references; no native result column is supplied. Text is quoted to distinguish empty strings and spaces. Delimiting quotation marks are not returned characters.

ROT13(“Hello, World!”) produces Uryyb, Jbeyq!. Applying the transformation again returns the original text. Spaces, comma and exclamation mark remain in place, so the structure of the message is immediately visible.

The upper-case group ABCXYZ becomes NOPKLM, and the lower-case group abcxyz becomes nopklm. Digits and hyphens in 123-45 are unchanged. These examples make the wraparound explicit instead of suggesting a shift in arbitrary Unicode character order.

A reasonable use is hiding a puzzle answer from accidental reading when everyone understands the convention. Do not use it to store passwords, account details or any material that needs confidentiality. Anyone can reverse it by applying the same public operation.

For each ASCII letter, the source adds thirteen to the character value and subtracts twenty-six if the result passes the end of the same-case alphabet. All other code units are copied to the output buffer. Two applications therefore rotate an ASCII letter by twenty-six positions, returning it to its original position.

The mixed string 日本語ＡＢＣé remains unchanged in this implementation. Full-width ＡＢＣ is not the ASCII sequence ABC. The long s ſ and dotless i ı are also outside the checked ranges and remain unchanged. This matters because case-conversion-based implementations in other software can behave differently for such characters.

The transformation preserves the number of UTF-16 code units in each example. That property does not mean it changes every visible letter, recognizes every writing system or performs a normalization step. It is precisely an ASCII-range substitution.

The inspected method is in LibreOffice’s date add-in source even though ROT13 is a text operation. Its documented OpenFormula storage namespace is ORG.OPENOFFICE.ROT13. The English worksheet spelling remains ROT13; the namespace is relevant when inspecting serialized formulas, not an instruction to type a different public function name. Inspected implementation.

The empty string stays empty, and the independently checked round trips restore every listed input. Those results establish the algorithm for these strings; no native application, import path, numeric coercion or error propagation was tested for this guide.

The Help uses the language of encryption and decryption, but the disclosed fixed transformation provides no security. It should not be described as a way to secure data, hide private information from a determined reader or verify that a message is authentic.

If a workbook must exchange ROT13 formulas with another spreadsheet application, confirm that program’s native function identity and Unicode handling separately. A matching ASCII example alone does not establish all-string compatibility.

SUBSTITUTE, UPPER, LOWER.

• Function-specific Help
• Complete versioned callback
• English native-name registration

The complete ASCII-only source method and all eight references were checked independently. No native result, import test or cross-product execution is claimed.