gprs_cipher.h

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#pragma once
 
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/utils.h>
 
#include <stdint.h>
 
#define GSM0464_CIPH_MAX_BLOCK  1523
 
/* 3GPP TS 24.008 § 10.5.5.3 */
enum gprs_ciph_algo {
        GPRS_ALGO_GEA0 = 0,
        GPRS_ALGO_GEA1 = 1,
        GPRS_ALGO_GEA2 = 2,
        GPRS_ALGO_GEA3 = 3,
        GPRS_ALGO_GEA4 = 4,
        _GPRS_ALGO_NUM
};
 
/* 3GPP TS 04.64 Table A.1: */
enum gprs_cipher_direction {
        GPRS_CIPH_MS2SGSN = 0,
        GPRS_CIPH_SGSN2MS = 1,
};
 
extern const struct value_string gprs_cipher_names[];
 
/* An implementation of a GPRS cipher */
struct gprs_cipher_impl {
        struct llist_head list;
        enum gprs_ciph_algo algo;
        const char *name;
        unsigned int priority;
 
        /* As specified in 04.64 Annex A.  Uses Kc, IV and direction
         * to generate the 1523 bytes cipher stream that need to be
         * XORed wit the plaintext for encrypt / ciphertext for decrypt */
        int (*run)(uint8_t *out, uint16_t len, uint8_t *kc, uint32_t iv,
                   enum gprs_cipher_direction direction);
};
 
/* register a cipher with the core (from a plugin) */
int gprs_cipher_register(struct gprs_cipher_impl *ciph);
 
/* load all available GPRS cipher plugins */
int gprs_cipher_load(const char *path);
 
/* function to be called by core code */
int gprs_cipher_run(uint8_t *out, uint16_t len, enum gprs_ciph_algo algo,
                    uint8_t *kc, uint32_t iv, enum gprs_cipher_direction dir);
 
/* Do we have an implementation for this cipher? */
int gprs_cipher_supported(enum gprs_ciph_algo algo);
 
/* Return key length for supported cipher, in bytes */
unsigned gprs_cipher_key_length(enum gprs_ciph_algo algo);
 
/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
uint32_t gprs_cipher_gen_input_ui(uint32_t iov_ui, uint8_t sapi, uint32_t lfn, uint32_t oc);
 
/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
uint32_t gprs_cipher_gen_input_i(uint32_t iov_i, uint32_t lfn, uint32_t oc);