Cellular Network Infrastructure » Core Network (CN) » OsmoHLR

According to openbsc/gsm_data_shared.h, there is an

#define A38_XOR_MIN_KEY_LEN     12
#define A38_XOR_MAX_KEY_LEN     16

but there is no concept of varying key lengths in osmo-hlr. For 2G, there is the 128bit KI and that's it:
In struct osmo_sub_auth_data we have only the uint8_t ki[OSMO_A5_MAX_KEY_LEN_BYTES] in .gsm.

In OsmoNITB, we allow to pass a shorter KI for the VTY command

subscriber imsi 123456 a3a8 xor 123456789abc123456789abc

and in the old struct gsm_auth_info we store an a3a8_ki_len, which gets populated from the binary length found in the db.

Adding VTY commands to osmo-hlr, the question is whether we should simply require a KI of 128bit and be done with it.

Otherwise we need to adjust libosmocore's struct osmo_sub_auth_data to indicate a ki_len.
And should probably add regression tests with varying KI lengths for XOR.