Draft:Linora Cipher

Linora Cipher

The Linora Cipher is a symmetric neighbor-chain encryption algorithm developed by the cryptographic enthusiast modify in 2025. It transforms alphabetic characters through modular arithmetic and chaining of differences between neighboring characters, resulting in ciphertext where each character depends on both the input and the immediately preceding character.

Overview

The Linora Cipher operates on lowercase alphabetic characters, mapping each letter to an integer value (a = 0 to z = 25). It uses a repeating numerical key and processes plaintext characters by computing modular differences relative to their neighbors. This chaining creates a dependency between consecutive characters, increasing diffusion and complicating frequency analysis.

Algorithm

Encryption

1. Convert each character of the plaintext to its corresponding integer value.
2. For the first character:
   1. Add the first key element to it modulo 26.
3. For each subsequent character:
   1. Compute the difference between the current plaintext character and the previous plaintext character modulo 26.
   2. Multiply this difference by the corresponding key element (cycled through the key).
   3. Take the result modulo 26 to obtain the ciphertext character.

Decryption

1. For the first character:
   1. Subtract the first key element from the ciphertext character modulo 26.
2. For each subsequent character:
   1. Multiply the ciphertext character by the modular inverse of the corresponding key element modulo 26.
   2. Add this result to the previous plaintext character modulo 26 to recover the current plaintext character.

Example

Given a plaintext such as "hello" and a key such as [3, 5, 7], each character is encrypted by the above process. The chaining ensures that a change in any plaintext character affects all subsequent ciphertext characters.

Security Considerations

The Linora Cipher introduces a chaining mechanism similar to cipher block chaining (CBC) modes in block ciphers but operates at the character level. While the chaining improves resistance against simple frequency analysis, the cipher is not considered secure for high-stakes cryptographic applications without additional measures. It is primarily intended for educational, experimental, or lightweight obfuscation use cases.

Authorship and License

The Linora Cipher was created by modify in 2025. The author retains copyright but permits usage and adaptation with appropriate attribution.

See also

• Modular arithmetic
• Symmetric-key algorithm
• Stream cipher
• Cipher block chaining

External links

• Linora Cipher repository – Reference implementation and documentation (if available).

Category:Cryptography Category:Symmetric-key algorithms Category:Stream ciphers Category:2025 introductions