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Contents
(in-package #:cl-user)
(defpackage #:crypto-square
(:use #:cl)
(:export #:encipher))
(in-package #:crypto-square)
(defun normalize (text)
(string-downcase (remove-if-not #'alpha-char-p text)))
(defun matrix-transpose (matrix)
(let ((new-matrix (make-array (array-dimensions matrix))))
(do ((x 0 (incf x)))
((= x (array-dimension matrix 0)) new-matrix)
(do ((y 0 (incf y)))
((< x y))
(setf (aref new-matrix x y) (aref matrix y x)
(aref new-matrix y x) (aref matrix x y))))))
(defun text->matrix (text)
(let* ((n (ceiling (sqrt (length text))))
(array (make-array (list n n) :initial-element #\Space)))
(do ((i 0 (incf i)))
((= i (length text)) array)
(setf (row-major-aref array i) (char text i)))))
(defun matrix->text (matrix)
(do ((rows (list))
(x 0 (incf x)))
((= x (array-total-size matrix))
(coerce (reverse rows) 'string))
(let ((c (row-major-aref matrix x)))
(when (and (not (zerop x))
(zerop (mod x (array-dimension matrix 0))))
(push #\Space rows))
(when (char/= c #\Space)
(push (row-major-aref matrix x) rows)))))
(defun encipher (plaintext)
(matrix->text
(matrix-transpose
(text->matrix
(normalize plaintext)))))
Version data entries
396 entries across 396 versions & 1 rubygems