Hill Cipher
A classical polygraphic substitution cipher that operates on blocks of letters using matrix multiplication.
Hill Cipher Encryption Tool
Encrypt or decrypt messages using the Hill Cipher algorithm
Enter comma-separated values for your key matrix. Leave empty to use default key.
About Hill Cipher
The Hill Cipher is a polygraphic substitution cipher based on linear algebra, invented by Lester S. Hill in 1929.
Matrix Visualization
Key Matrix (K)
[a b]
[c d]
[c d]
Inverse Matrix (K⁻¹)
[d -b]
[-c a]
[-c a]
The determinant must be non-zero and coprime with 26 for the key matrix to be valid.