Use this classical cipher operation for education, puzzles, interoperability with historical text, or reversible obfuscation where modern security is not required.

Text

Required string input.

Multiplier A

Required integer input.

Shift B

Required integer input.

Encrypt Latin letters with the affine cipher ((a x) + b) mod 26, preserving case and leaving non-letters unchanged. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Encoded text

The resulting encoded text returned as a string.

• Classical substitution and XOR demonstrations are not secure merely because the result looks unreadable. Small key spaces, repeated keys, language statistics, known plaintext, encoding mistakes, and unauthenticated modification make them unsuitable for protecting sensitive data.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

For real confidentiality and integrity, use a reviewed authenticated-encryption construction with secure key generation and management. Preserve the alphabet, encoding, key convention, and treatment of unsupported characters for reproducibility.

• Caesar Shift Cipher

  Shift Latin letters through the alphabet with wrap-around while preserving case; negative shifts decode.

• ROT18 Cipher

  Apply ROT13 to letters and ROT5 to digits simultaneously, leaving all other characters unchanged.

• ROT5 Cipher

  Rotate decimal digits 0-9 by five positions while leaving every other character unchanged.