initial code commit

src/caesarcrypt.c

@@ -0,0 +1,60 @@
+/*
+  * Filename: caesarcrypt.c
+  * Authors(s): Roland (r.weirhowell@gmail.com)
+  * Description: Encrypt and decrypt text using the Caesar Cipher algorithm
+  *
+  * This Source Code Form is subject to the terms of the Mozilla Public
+  * License, v. 2.0. If a copy of the MPL was not distributed with this
+  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+*/
+
+#include "crypt.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+
+int main()
+{
+	fputs(
+		 "1. Encrypt message\n"
+		 "2. Decrypt message\n"
+		 "Pick operation mode: "
+		,stdout
+	);
+	char buf[4];
+	fgets(buf, 3, stdin);
+	int choice = strtol(buf, NULL, 10);
+	
+	char* msg = calloc(128, sizeof(char));
+
+	fputs("Enter your message text: ", stdout);
+	if (msg) fgets(msg, 128, stdin);
+
+	fputs("Enter your key (shift value): ", stdout);
+	fgets(buf, 4, stdin);
+	int key = strtol(buf, NULL, 10);
+
+	if (choice == 1)
+	{
+		caesar_encrypt(msg, 128, key);
+		puts("\nYour encrypted message is:");
+		for (int i = 0; i < 128 && msg[i]; i++)
+		{
+			putchar(msg[i]);
+		}
+	}
+	else if (choice == 2)
+	{
+		caesar_decrypt(msg, 128, key);
+		puts("\nYour decrypted message is:");
+		for (int i = 0; i < 128 && msg[i]; i++)
+		{
+			putchar(msg[i]);
+		}
+	}
+
+	return 0;
+}

src/crypt.c

@@ -0,0 +1,25 @@
+/*
+  * Filename: crypt.c
+  * Authors(s): Roland (r.weirhowell@gmail.com)
+  * Description: Perform caesar cipher cryptographic operations
+  *
+  * This Source Code Form is subject to the terms of the Mozilla Public
+  * License, v. 2.0. If a copy of the MPL was not distributed with this
+  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+*/
+
+#include "crypt.h"
+
+
+void caesar_encrypt(char* str, int size, int key)
+{
+	for (int i = 0; i < size && str[i] != '\n'; i++)
+		if (str[i] != ' ') str[i] += key % 26;
+}
+
+
+void caesar_decrypt(char* str, int size, int key)
+{
+	for (int i = 0; i < size && str[i] != '\n'; i++)
+		if (str[i] != ' ') str[i] -= key % 26;
+}

src/crypt.h

@@ -0,0 +1,16 @@
+/*
+  * Filename: crypt.h
+  * Authors(s): Roland (r.weirhowell@gmail.com)
+  * Description: Header file for crypt.c
+  *
+  * This Source Code Form is subject to the terms of the Mozilla Public
+  * License, v. 2.0. If a copy of the MPL was not distributed with this
+  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+*/
+
+#pragma once
+
+
+void caesar_encrypt(char* str, int size, int key);
+
+void caesar_decrypt(char* str, int size, int key);