diff --git a/mme/key_derivation.h b/mme/key_derivation.h
new file mode 100644
index 0000000..496f52b
--- /dev/null
+++ b/mme/key_derivation.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <stdint.h>
+
+#define HSS_SQN_LEN 6
+#define HSS_AK_LEN 6
+
+void hss_auc_kasme(const uint8_t *ck, const uint8_t *ik,
+        const uint8_t plmn_id[3], const uint8_t *sqn,  const uint8_t *ak,
+        uint8_t *kasme);
+
+/* Algorithm Type Distinguishers */
+#define MME_KDF_NAS_ENC_ALG 0x01
+#define MME_KDF_NAS_INT_ALG 0x02
+
+void mme_kdf_nas(uint8_t algorithm_type_distinguishers,
+    uint8_t algorithm_identity, const uint8_t *kasme, uint8_t *knas);
+
+void mme_kdf_enb(const uint8_t *kasme, uint32_t ul_count, uint8_t *kenb);
+
+void mme_kdf_nh(const uint8_t *kasme, const uint8_t *sync_input, uint8_t *kenb);