From d6813fa116f34cf111b72e276ead09686e81fe77 Mon Sep 17 00:00:00 2001 From: Smaug123 Date: Thu, 7 Jan 2016 12:29:09 +0000 Subject: [PATCH] Add "matrix must be invertible" to Hill readme --- README.md | 3 +++ 1 file changed, 3 insertions(+) diff --git a/README.md b/README.md index e5c6ad7..3b109c9 100644 --- a/README.md +++ b/README.md @@ -198,6 +198,9 @@ encrypt_hill("Hello, World!", [1 2; 5 7]) Notice that the input has been made uppercase and symbols have been stripped out. +The key matrix must be invertible mod 26. That is, its determinant must be +coprime to 26. + Encrypt the same text with the same key, this time represented as a string: ```julia