Add skeleton for encrypt program.

Encrypt.c

@@ -0,0 +1,14 @@
+#include "Buffer.h"
+#include "Common.h"
+
+#include <stdio.h>
+
+int main( int argc, const char *argv[] ) 
+{
+	if (argc != 3) {
+		fprintf( stderr, "Call %s <input> <output>\n", argv[0] );
+		return 1;
+	}
+  
+  return 0;
+}

Makefile

@@ -1,10 +1,14 @@
-all: Decrypt
+all: Decrypt Encrypt	
 
 Decrypt: Decrypt.o Buffer.o
-	clang -o $@ Decrypt.o Buffer.o
+	clang -o $@ $^
+
+Encrypt: Encrypt.o Buffer.o
+	clang -o $@ $^
 
 Decrypt.o: Decrypt.c Buffer.h Common.h
 Buffer.o: Buffer.c Buffer.h
+Encrypt.o: Encrypt.c Buffer.h Common.h
 
 .c.o:
 	clang -c -o $@ $<