mirror of https://gerrit.osmocom.org/osmo-tetra
128 lines
4.6 KiB
C
128 lines
4.6 KiB
C
/* Cryptography related helper, key management and wrapper functions */
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/*
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* Copyright (C) 2023 Midnight Blue B.V.
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*
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* Author: Wouter Bokslag <w.bokslag [ ] midnightblue [ ] nl>
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*
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* SPDX-License-Identifier: AGPL-3.0+
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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* See the COPYING file in the main directory for details.
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*/
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#ifndef TETRA_CRYPTO_H
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#define TETRA_CRYPTO_H
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#include <inttypes.h>
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#include <stdbool.h>
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#include "../tetra_prim.h"
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#include "../tetra_tdma.h"
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#include "../tetra_mac_pdu.h"
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#define TCDB_ALLOC_BLOCK_SIZE 16
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enum tetra_key_type {
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KEYTYPE_UNDEFINED = 0,
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/* Keytypes usable as ECK after applying TB5 */
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KEYTYPE_CCK_SCK = 1, /* SCK in class 2, CCK in class 3 networks */
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KEYTYPE_DCK = 2, /* FIXME: add support for DCK */
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KEYTYPE_MGCK = 4, /* FIXME: add support for MGCK */
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KEYTYPE_GCK = 8, /* FIXME: add support. Used with SCK/CCK to derive MGCK */
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};
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enum tetra_ksg_type {
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UNKNOWN = 0,
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KSG_TEA1 = 1, /* KSG number value 0 */
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KSG_TEA2 = 2, /* KSG number value 1 */
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KSG_TEA3 = 3, /* KSG number value 2 */
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KSG_TEA4 = 4, /* KSG number value 3 */
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KSG_TEA5 = 5, /* KSG number value 4 */
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KSG_TEA6 = 6, /* KSG number value 5 */
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KSG_TEA7 = 7, /* KSG number value 6 */
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KSG_PROPRIETARY = 8, /* KSG number values 9-15 */
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};
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enum tetra_security_class {
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NETWORK_CLASS_UNDEFINED = 0,
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NETWORK_CLASS_1 = 1,
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NETWORK_CLASS_2 = 2,
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NETWORK_CLASS_3 = 3,
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};
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struct tetra_netinfo {
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uint32_t mcc;
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uint32_t mnc;
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enum tetra_ksg_type ksg_type; /* KSG used in this network */
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enum tetra_security_class security_class; /* Security class this network employs */
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};
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struct tetra_key {
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uint32_t index; /* position in key list */
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uint32_t mnc;
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uint32_t mcc;
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enum tetra_key_type key_type;
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uint32_t key_num; /* key_vn or whatever key numbering system is relevant for this key type */
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uint32_t addr; /* ISSI, GSSI, or whatever address is relevant for this key type */
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uint8_t key[16]; /* Currently keys are 80 bits, but we may want to support 128-bit keys as well */
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struct tetra_netinfo *network_info; /* Network with which the key is associated */
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};
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struct tetra_crypto_database {
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uint32_t num_keys;
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struct tetra_key *keys;
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uint32_t num_nets;
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struct tetra_netinfo *nets;
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};
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extern struct tetra_crypto_database *tcdb;
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struct tetra_crypto_state {
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int mnc; /* Network info for selecting keys */
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int mcc; /* Network info for selecting keys */
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int cck_id; /* CCK or SCK id used on network (from SYSINFO) */
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int hn; /* Hyperframe number for IV (from SYSINFO) */
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int la; /* location area for TB5 */
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int cn; /* carrier number for TB5. WARNING: only set correctly if tuned to main control channel */
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int cc; /* colour code for TB5 */
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struct tetra_netinfo *network; /* pointer to network info struct loaded from file */
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struct tetra_key *cck; /* pointer to CCK or SCK for this network and version (from SYSINFO) */
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};
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const char *tetra_get_key_type_name(enum tetra_key_type);
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const char *tetra_get_ksg_type_name(enum tetra_ksg_type);
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const char *tetra_get_security_class_name(uint8_t pdut);
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/* Key loading / unloading */
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void tetra_crypto_state_init(struct tetra_crypto_state *tcs);
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int load_keystore(char *filename);
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/* Keystream generation and decryption functions */
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uint32_t tea_build_iv(struct tetra_tdma_time *tm, uint16_t hn, uint8_t dir);
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bool decrypt_identity(struct tetra_crypto_state *tcs, struct tetra_addr *addr);
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bool decrypt_mac_element(struct tetra_crypto_state *tcs, struct tetra_tmvsap_prim *tmvp, struct tetra_key *key, int l1_len, int tmpdu_offset);
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bool decrypt_voice_timeslot(struct tetra_crypto_state *tcs, struct tetra_tdma_time *tdma_time, int16_t *type1_bits);
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/* Key selection and crypto state management */
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struct tetra_netinfo *get_network_info(int mcc, int mnc);
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struct tetra_key *get_ksg_key(struct tetra_crypto_state *tcs, int addr);
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void update_current_network(struct tetra_crypto_state *tcs, int mcc, int mnc);
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void update_current_cck(struct tetra_crypto_state *tcs);
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char *dump_network_info(struct tetra_netinfo *network);
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char *dump_key(struct tetra_key *k);
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#endif /* TETRA_CRYPTO_H */
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