🔐 Hill Cipher

Hill Cipher — Linear algebra block cipher (matrix multiplication)

📐 Encryption Formula

C = M × K mod 26

D = K⁻¹ × C mod 26

K is a 2×2 invertible matrix, gcd(det(K), 26) = 1

Matrix Coefficients

Each coefficient mod 26

Matrix Preview:

Input Plaintext (letters only)

Non-letter characters will be ignored; insufficient length auto-padded with X