diff --git a/lib/decoding/osmocom/gsm/auth_core.c b/lib/decoding/osmocom/gsm/auth_core.c
new file mode 100644
index 0000000..230500e
--- /dev/null
+++ b/lib/decoding/osmocom/gsm/auth_core.c
@@ -0,0 +1,252 @@
+/* (C) 2010-2012 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+//#include "config.h"
+
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/linuxlist.h>
+//#include <osmocom/core/plugin.h>
+
+#include <osmocom/crypt/auth.h>
+
+/*! \addtogroup auth
+ *  @{
+ *  GSM/GPRS/3G authentication core infrastructure
+ *
+ * \file auth_core.c */
+
+static LLIST_HEAD(osmo_auths);
+
+static struct osmo_auth_impl *selected_auths[_OSMO_AUTH_ALG_NUM];
+
+/*! Register an authentication algorithm implementation with the core
+ *  \param[in] impl Structure describing implementation and it's callbacks
+ *  \returns 0 on success, or a negative error code on failure
+ *
+ * This function is called by an authentication implementation plugin to
+ * register itself with the authentication core.
+ */
+int osmo_auth_register(struct osmo_auth_impl *impl)
+{
+	if (impl->algo >= ARRAY_SIZE(selected_auths))
+		return -ERANGE;
+
+	llist_add_tail(&impl->list, &osmo_auths);
+
+	/* check if we want to select this implementation over others */
+	if (!selected_auths[impl->algo] ||
+	    (selected_auths[impl->algo]->priority > impl->priority))
+		selected_auths[impl->algo] = impl;
+
+	return 0;
+}
+
+/*! Load all available authentication plugins from the given path
+ *  \param[in] path Path name of the directory containing the plugins
+ *  \returns number of plugins loaded in case of success, negative in case of error
+ *
+ * This function will load all plugins contained in the specified path.
+ */
+int osmo_auth_load(const char *path)
+{
+	/* load all plugins available from path */
+/*#if !defined(EMBEDDED)
+	return osmo_plugin_load_all(path);
+#else*/
+	return -1;
+/*#endif*/
+}
+
+/*! Determine if a given authentication algorithm is supported
+ *  \param[in] algo Algorithm which should be checked
+ *  \returns 1 if algo is supported, 0 if not, negative error on failure
+ *
+ * This function is used by an application to determine at runtime if a
+ * given authentication algorithm is supported or not.
+ */
+int osmo_auth_supported(enum osmo_auth_algo algo)
+{
+	if (algo >= ARRAY_SIZE(selected_auths))
+		return -ERANGE;
+
+	if (selected_auths[algo])
+		return 1;
+
+	return 0;
+}
+
+/* C5 function to derive UMTS IK from GSM Kc */
+static inline void c5_function(uint8_t *ik, const uint8_t *kc)
+{
+	unsigned int i;
+
+	for (i = 0; i < 4; i++)
+		ik[i] = kc[i] ^ kc[i+4];
+	memcpy(ik+4, kc, 8);
+	for (i = 12; i < 16; i++)
+		ik[i] = ik[i-12];
+}
+
+/* C4 function to derive UMTS CK from GSM Kc */
+void osmo_c4(uint8_t *ck, const uint8_t *kc)
+{
+	memcpy(ck, kc, 8);
+	memcpy(ck+8, kc, 8);
+}
+
+/*! Generate 3G CK + IK from 2G authentication vector
+ *  \param vec Authentication Vector to be modified
+ *  \returns 1 if the vector was changed, 0 otherwise
+ *
+ * This function performs the C5 and C4 functions to derive the UMTS key
+ * material from the GSM key material in the supplied vector, _if_ the input
+ * vector doesn't yet have UMTS authentication capability.
+ */
+int osmo_auth_3g_from_2g(struct osmo_auth_vector *vec)
+{
+	if ((vec->auth_types & OSMO_AUTH_TYPE_GSM) &&
+	    !(vec->auth_types & OSMO_AUTH_TYPE_UMTS)) {
+		c5_function(vec->ik, vec->kc);
+		osmo_c4(vec->ck, vec->kc);
+		/* We cannot actually set OSMO_AUTH_TYPE_UMTS as we have no
+		 * AUTN and no RES, and thus can only perform GSM
+		 * authentication with this tuple.
+		 */
+		return 1;
+	}
+
+	return 0;
+}
+
+/*! Generate authentication vector
+ *  \param[out] vec Generated authentication vector
+ *  \param[in] aud Subscriber-specific key material
+ *  \param[in] _rand Random challenge to be used
+ *  \returns 0 on success, negative error on failure
+ *
+ * This function performs the core cryptographic function of the AUC,
+ * computing authentication triples/quintuples based on the permanent
+ * subscriber data and a random value.  The result is what is forwarded
+ * by the AUC via HLR and VLR to the MSC which will then be able to
+ * invoke authentication with the MS
+ */
+int osmo_auth_gen_vec(struct osmo_auth_vector *vec,
+		      struct osmo_sub_auth_data *aud,
+		      const uint8_t *_rand)
+{
+	struct osmo_auth_impl *impl = selected_auths[aud->algo];
+	int rc;
+
+	if (!impl)
+		return -ENOENT;
+
+	rc = impl->gen_vec(vec, aud, _rand);
+	if (rc < 0)
+		return rc;
+
+	memcpy(vec->rand, _rand, sizeof(vec->rand));
+
+	return 0;
+}
+
+/*! Generate authentication vector and re-sync sequence
+ *  \param[out] vec Generated authentication vector
+ *  \param[in] aud Subscriber-specific key material
+ *  \param[in] auts AUTS value sent by the SIM/MS
+ *  \param[in] rand_auts RAND value sent by the SIM/MS
+ *  \param[in] _rand Random challenge to be used to generate vector
+ *  \returns 0 on success, negative error on failure
+ *
+ * This function performs a special variant of the  core cryptographic
+ * function of the AUC: computing authentication triples/quintuples
+ * based on the permanent subscriber data, a random value as well as the
+ * AUTS and RAND values returned by the SIM/MS.  This special variant is
+ * needed if the sequence numbers between MS and AUC have for some
+ * reason become different.
+ */
+int osmo_auth_gen_vec_auts(struct osmo_auth_vector *vec,
+			   struct osmo_sub_auth_data *aud,
+			   const uint8_t *auts, const uint8_t *rand_auts,
+			   const uint8_t *_rand)
+{
+	struct osmo_auth_impl *impl = selected_auths[aud->algo];
+	int rc;
+
+	if (!impl || !impl->gen_vec_auts)
+		return -ENOENT;
+
+	rc = impl->gen_vec_auts(vec, aud, auts, rand_auts, _rand);
+	if (rc < 0)
+		return rc;
+
+	memcpy(vec->rand, _rand, sizeof(vec->rand));
+
+	return 0;
+}
+
+static const struct value_string auth_alg_vals[] = {
+	{ OSMO_AUTH_ALG_NONE, "None" },
+	{ OSMO_AUTH_ALG_COMP128v1, "COMP128v1" },
+	{ OSMO_AUTH_ALG_COMP128v2, "COMP128v2" },
+	{ OSMO_AUTH_ALG_COMP128v3, "COMP128v3" },
+	{ OSMO_AUTH_ALG_XOR, "XOR" },
+	{ OSMO_AUTH_ALG_MILENAGE, "MILENAGE" },
+	{ 0, NULL }
+};
+
+/*! Get human-readable name of authentication algorithm *
+const char *osmo_auth_alg_name(enum osmo_auth_algo alg)
+{
+	return get_value_string(auth_alg_vals, alg);
+}
+
+/*! Parse human-readable name of authentication algorithm */
+/*enum osmo_auth_algo osmo_auth_alg_parse(const char *name)
+{
+	return get_string_value(auth_alg_vals, name);
+}
+*/
+const struct value_string osmo_sub_auth_type_names[] = {
+	{ OSMO_AUTH_TYPE_NONE, "None" },
+	{ OSMO_AUTH_TYPE_GSM, "GSM" },
+	{ OSMO_AUTH_TYPE_UMTS, "UMTS" },
+	{ 0, NULL }
+};
+
+/* Derive GSM AKA ciphering key Kc from UMTS AKA CK and IK (auth function c3 from 3GPP TS 33.103 §
+ * 4.6.1).
+ * \param[out] kc  GSM AKA Kc, 8 byte target buffer.
+ * \param[in] ck  UMTS AKA CK, 16 byte input buffer.
+ * \param[in] ik  UMTS AKA IK, 16 byte input buffer.
+ */
+void osmo_auth_c3(uint8_t kc[], const uint8_t ck[], const uint8_t ik[])
+{
+	int i;
+	for (i = 0; i < 8; i++)
+		kc[i] = ck[i] ^ ck[i + 8] ^ ik[i] ^ ik[i + 8];
+}
+
+/*! @} */