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SDRTrunk .mbe File Replay:

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Tweak RC4 Keystream Creation to only create second keystream when P25p1, and only make as much keystream as needed; #298
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lwvmobile
2025-06-23 02:37:45 -04:00
parent ccbaef8541
commit 4e1b1ac98e
1 changed files with 9 additions and 6 deletions
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15
src/dsd_file.c
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@@ -1379,19 +1379,22 @@ void read_sdrtrunk_json_format (dsd_opts * opts, dsd_state * state)
//load the str_buffer into the IV portion of kiv
parse_raw_user_string(str_buffer, kiv+5);
rc4_block_output (rc4_db, rc4_mod, 375, kiv, ks_bytes);
rc4_block_output (rc4_db, rc4_mod, 200, kiv, ks_bytes);
unpack_byte_array_into_bit_array(ks_bytes, ks, 375);
unpack_byte_array_into_bit_array(ks_bytes, ks, 200);
//reverse lfsr on IV and create keystream with that as well
//due to out of order execution on P25p1 ESS sync.
reverse_lfsr_64_to_len (kiv+5, 64);
if (protocol == 1)
{
reverse_lfsr_64_to_len (kiv+5, 64);
memset(ks_bytes, 0, sizeof(ks_bytes));
memset(ks_bytes, 0, sizeof(ks_bytes));
rc4_block_output (rc4_db, rc4_mod, 375, kiv, ks_bytes);
rc4_block_output (rc4_db, rc4_mod, 200, kiv, ks_bytes);
unpack_byte_array_into_bit_array(ks_bytes, ks_i, 375);
unpack_byte_array_into_bit_array(ks_bytes, ks_i, 200);
}
} //end test