Add transposition cipher

Networking/TranspositionCipher.c

@@ -0,0 +1,76 @@
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+
+#define MAX_LENGTH 1024
+#define MAX_KEY_SIZE 8
+
+void find_column_order(char key[], int column_order[]) {
+    int i, j, pos, min_index;
+    int marked[MAX_KEY_SIZE] = {0};
+    char min;
+
+    for (i = 0, pos = 0; i < strlen(key); i++) {
+        min = CHAR_MAX;
+        min_index = -1;
+        for (j = 0; j < strlen(key); j++) {
+            if (!marked[j] && key[j] < min) {
+                min = key[j];
+                min_index = j;
+            }
+        }
+        if (min_index == -1)
+            break;
+        column_order[pos++] = min_index;
+        marked[min_index] = 1;
+        printf("%d, ", column_order[pos-1]);
+    }
+}
+
+void str_to_matrix(char plain_text[], char plain_text_matrix[][MAX_KEY_SIZE], int key_length) {
+    int row, col, i;
+
+    for (row = 0, i = 0; i < strlen(plain_text); row++) {
+        for (col = 0; col < key_length && i < strlen(plain_text); col++) {
+            plain_text_matrix[row][col] = plain_text[i++];
+            printf("%c", plain_text_matrix[row][col]);
+        }
+        printf("\n");
+    }
+}
+
+void transposition_cipher(char plain_text[], char key[], char cipher_text[]) {
+    char plain_text_matrix[MAX_LENGTH / MAX_KEY_SIZE + 1][MAX_KEY_SIZE];
+
+    str_to_matrix(plain_text, plain_text_matrix, strlen(key));
+
+    int column_order[MAX_KEY_SIZE];
+    find_column_order(key, column_order);
+
+    printf("\nCipher text : ");
+    int row, col, i;
+    for (i = 0; i < strlen(key); i++) {
+        col = column_order[i];
+        for (row = 0; row < strlen(key); row++) {
+            printf("%c", plain_text_matrix[row][col]);
+        }
+        printf(" ");
+    }
+    printf("\n");
+}
+
+int main() {
+    char plain_text[MAX_LENGTH];
+    char key[MAX_KEY_SIZE];
+    char cipher_text[MAX_LENGTH];
+
+    printf("Enter plain-text : ");
+    scanf("%s", plain_text);
+
+    printf("Enter key : ");
+    scanf("%s", key);
+
+    transposition_cipher(plain_text, key, cipher_text);
+
+    return 0;
+}