diff --git a/include/osmocom/gsm/kasumi.h b/include/osmocom/gsm/kasumi.h
new file mode 100644
index 0000000..8ecf65f
--- /dev/null
+++ b/include/osmocom/gsm/kasumi.h
@@ -0,0 +1,48 @@
+/*
+ * KASUMI header
+ *
+ * See kasumi.c for details
+ * The parameters are described in TS 135 202.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+/*! \brief Single iteration of KASUMI cipher
+ *  \param[in] P Block, 64 bits to be processed in this round
+ *  \param[in] KLi1 Expanded subkeys
+ *  \param[in] KLi2 Expanded subkeys
+ *  \param[in] KOi1 Expanded subkeys
+ *  \param[in] KOi2 Expanded subkeys
+ *  \param[in] KOi3 Expanded subkeys
+ *  \param[in] KIi1 Expanded subkeys
+ *  \param[in] KIi2 Expanded subkeys
+ *  \param[in] KIi3 Expanded subkeys
+ *  \returns processed block of 64 bits
+ */
+uint64_t _kasumi(uint64_t P, const uint16_t *KLi1, const uint16_t *KLi2, const uint16_t *KOi1, const uint16_t *KOi2, const uint16_t *KOi3, const uint16_t *KIi1, const uint16_t *KIi2, const uint16_t *KIi3);
+
+/*! \brief Implementation of the KGCORE algorithm (used by A5/3, A5/4, GEA3, GEA4 and ECSD)
+ *  \param[in] CA
+ *  \param[in] cb
+ *  \param[in] cc
+ *  \param[in] cd
+ *  \param[in] ck 8-bytes long key
+ *  \param[out] co cl-dependent
+ *  \param[in] cl
+ */
+void _kasumi_kgcore(uint8_t CA, uint8_t cb, uint32_t cc, uint8_t cd, const uint8_t *ck, uint8_t *co, uint16_t cl);
+
+/*! \brief Expand key into set of subkeys - see TS 135 202 for details
+ *  \param[in] key (128 bits) as array of bytes
+ *  \param[out] KLi1 Expanded subkeys
+ *  \param[out] KLi2 Expanded subkeys
+ *  \param[out] KOi1 Expanded subkeys
+ *  \param[out] KOi2 Expanded subkeys
+ *  \param[out] KOi3 Expanded subkeys
+ *  \param[out] KIi1 Expanded subkeys
+ *  \param[out] KIi2 Expanded subkeys
+ *  \param[out] KIi3 Expanded subkeys
+ */
+void _kasumi_key_expand(const uint8_t *key, uint16_t *KLi1, uint16_t *KLi2, uint16_t *KOi1, uint16_t *KOi2, uint16_t *KOi3, uint16_t *KIi1, uint16_t *KIi2, uint16_t *KIi3);