diff --git a/common/MD5.cpp b/common/MD5.cpp
new file mode 100644
index 0000000..b9fc3c6
--- /dev/null
+++ b/common/MD5.cpp
@@ -0,0 +1,13 @@
+#include "common/MD5.hpp"
+
+void MD5Init(MD5_CTX* context) {
+    // TODO
+}
+
+void MD5Update(MD5_CTX* context, uint8_t* input, uint32_t inputLen) {
+    // TODO
+}
+
+void MD5Final(uint8_t digest[16], MD5_CTX* context) {
+    // TODO
+}
diff --git a/common/MD5.hpp b/common/MD5.hpp
new file mode 100644
index 0000000..7ad435b
--- /dev/null
+++ b/common/MD5.hpp
@@ -0,0 +1,18 @@
+#ifndef COMMON_MD5_HPP
+#define COMMON_MD5_HPP
+
+#include <cstdint>
+
+typedef struct {
+    uint32_t state[4];
+    uint32_t count[2];
+    uint8_t buffer[64];
+} MD5_CTX;
+
+void MD5Init(MD5_CTX* context);
+
+void MD5Update(MD5_CTX* context, uint8_t* input, uint32_t inputLen);
+
+void MD5Final(uint8_t digest[16], MD5_CTX* context);
+
+#endif