diff --git a/include/osmocom/crypt/Makefile.am b/include/osmocom/crypt/Makefile.am
index 7ce69fd..e4a6e53 100644
--- a/include/osmocom/crypt/Makefile.am
+++ b/include/osmocom/crypt/Makefile.am
@@ -1,3 +1,3 @@
-osmocrypt_HEADERS = gprs_cipher.h
+osmocrypt_HEADERS = gprs_cipher.h auth.h
 
 osmocryptdir = $(includedir)/osmocom/crypt
diff --git a/include/osmocom/crypt/auth.h b/include/osmocom/crypt/auth.h
new file mode 100644
index 0000000..12690f8
--- /dev/null
+++ b/include/osmocom/crypt/auth.h
@@ -0,0 +1,87 @@
+#ifndef _OSMOCRYPTO_AUTH_H
+#define _OSMOCRYPTO_AUTH_H
+
+#include <stdint.h>
+
+#include <osmocom/core/linuxlist.h>
+
+/*! \brief Authentication Type */
+enum osmo_sub_auth_type {
+	OSMO_AUTH_TYPE_NONE	= 0x00,
+	OSMO_AUTH_TYPE_GSM	= 0x01,
+	OSMO_AUTH_TYPE_UMTS	= 0x02,
+};
+
+/*! \brief Authentication Algorithm */
+enum osmo_auth_algo {
+	OSMO_AUTH_ALG_NONE,
+	OSMO_AUTH_ALG_COMP128v1,
+	OSMO_AUTH_ALG_COMP128v2,
+	OSMO_AUTH_ALG_COMP128v3,
+	OSMO_AUTH_ALG_XOR,
+	OSMO_AUTH_ALG_MILENAGE,
+	_OSMO_AUTH_ALG_NUM,
+};
+
+/*! \brief permanent (secret) subscriber auth data */
+struct osmo_sub_auth_data {
+	enum osmo_sub_auth_type type;
+	enum osmo_auth_algo algo;
+	union {
+		struct {
+			uint8_t opc[16];
+			uint8_t k[16];
+			uint8_t amf[2];
+			uint64_t sqn;
+		} umts;
+		struct {
+			uint8_t ki[16];
+		} gsm;
+	};
+};
+
+/* data structure describing a computed auth vector, generated by AuC */
+struct osmo_auth_vector {
+	uint8_t rand[16];
+	uint8_t autn[16];
+	uint8_t ck[16];
+	uint8_t ik[16];
+	uint8_t res[16];
+	uint8_t res_len;
+	uint8_t kc[8];
+	uint8_t sres[4];
+	uint32_t auth_types;	/*!< bitmask of OSMO_AUTH_TYPE_* */
+};
+
+/* \brief An implementation of an authentication algorithm */
+struct osmo_auth_impl {
+	struct llist_head list;
+	enum osmo_auth_algo algo;
+	const char *name;
+	unsigned int priority;
+
+	int (*gen_vec)(struct osmo_auth_vector *vec,
+			struct osmo_sub_auth_data *aud,
+			const uint8_t *_rand);
+
+	int (*gen_vec_auts)(struct osmo_auth_vector *vec,
+			    struct osmo_sub_auth_data *aud,
+			    const uint8_t *rand_auts, const uint8_t *auts,
+			    const uint8_t *_rand);
+};
+
+int osmo_auth_gen_vec(struct osmo_auth_vector *vec,
+		      struct osmo_sub_auth_data *aud, const uint8_t *_rand);
+
+int osmo_auth_gen_vec_auts(struct osmo_auth_vector *vec,
+			   struct osmo_sub_auth_data *aud,
+			   const uint8_t *rand_auts, const uint8_t *auts,
+			   const uint8_t *_rand);
+
+int osmo_auth_register(struct osmo_auth_impl *impl);
+
+int osmo_auth_load(const char *path);
+
+int osmo_auth_supported(enum osmo_auth_algo algo);
+
+#endif /* _OSMOCRYPTO_AUTH_H */