mirror of
https://github.com/lwvmobile/dsd-fme.git
synced 2026-11-13 01:07:24 -05:00
a5151686ec
Adding a new method to allow a user to enter a generic keystream len and static keystream via a string that is loaded into a bit array to xor against ambe frames; This method is intended to be used to allow
126 lines
3.3 KiB
C
126 lines
3.3 KiB
C
#include "dsd.h"
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void ken_dmr_scrambler_keystream_creation(dsd_state * state, char * input)
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{
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/*
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SLOT 1 Protected LC FLCO=0x00 FID=0x20 <--this link appears to indicate scrambler usage from Kenwood on DMR
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DMR PDU Payload [80][20][40][00][00][01][00][00][01] SB: 00000000000 - 000;
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SLOT 1 TGT=1 SRC=1 FLCO=0x00 FID=0x00 SVC=0x00 Group Call <--different call, no scrambler from same Kenwood Radio
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DMR PDU Payload [00][00][00][00][00][01][00][00][01]
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For This, we could possible transition this to not be enforced
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since we may have a positive indicator in link control,
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but needs further samples and validation
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*/
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int lfsr = 0, bit = 0;
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sscanf (input, "%d", &lfsr);
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fprintf (stderr,"DMR Kenwood 15-bit Scrambler Key %05d with Forced Application\n", lfsr);
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for (int i = 0; i < 882; i++)
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{
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state->static_ks_bits[0][i] = lfsr & 0x1;
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state->static_ks_bits[1][i] = lfsr & 0x1;
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bit = ( (lfsr >> 1) ^ (lfsr >> 0) ) & 1;
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lfsr = ( (lfsr >> 1 ) | (bit << 14) );
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}
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state->ken_sc = 1;
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}
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void anytone_bp_keystream_creation(dsd_state * state, char * input)
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{
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uint16_t key = 0;
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uint16_t kperm = 0;
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sscanf (input, "%hX", &key);
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key &= 0xFFFF; //truncate to 16-bits
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//calculate key permutation using simple operations
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uint8_t nib1, nib2, nib3, nib4;
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//nib 1 and 3 are simple inversions
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nib1 = ~(key >> 12) & 0xF;
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nib3 = ~(key >> 4) & 0xF;
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//nib 2 and 4 are +8 and mod 16 (& 0xF)
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nib2 = (((key >> 8) & 0xF) + 8) % 16;
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nib4 = (((key >> 0) & 0xF) + 8) % 16;
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//debug
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// fprintf (stderr, "{%01X, %01X, %01X, %01X}", nib1, nib2, nib3, nib4);
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kperm = nib1;
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kperm <<= 4;
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kperm |= nib2;
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kperm <<= 4;
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kperm |= nib3;
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kperm <<= 4;
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kperm |= nib4;
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//load bits into static keystream
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for (int i = 0; i < 16; i++)
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{
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state->static_ks_bits[0][i] = (kperm >> (15-i)) & 1;
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state->static_ks_bits[1][i] = (kperm >> (15-i)) & 1;
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}
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fprintf (stderr,"DMR Anytone Basic 16-bit Key 0x%04X with Forced Application\n", key);
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state->any_bp = 1;
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}
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void straight_mod_xor_keystream_creation(dsd_state * state, char * input)
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{
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uint16_t len = 0;
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char * curr;
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curr = strtok(input, ":"); //should be len (mod) of key (decimal)
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if (curr != NULL)
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sscanf (curr, "%hd", &len);
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else goto END_KS;
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//len sanity check, can't be greater than 882
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if (len > 882)
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len = 882;
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curr = strtok(NULL, ":"); //should be key in hex
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if (curr != NULL)
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{
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//continue
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}
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else goto END_KS;
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uint8_t ks_bytes[112];
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memset (ks_bytes, 0, sizeof(ks_bytes));
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parse_raw_user_string(curr, ks_bytes);
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uint8_t ks_bits[896];
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memset(ks_bits, 0, sizeof(ks_bits));
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uint16_t unpack_len = len / 8;
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if (len % 8)
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unpack_len++;
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unpack_byte_array_into_bit_array(ks_bytes, ks_bits, unpack_len);
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for (uint16_t i = 0; i < len; i++)
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{
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state->static_ks_bits[0][i] = ks_bits[i];
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state->static_ks_bits[1][i] = ks_bits[i];
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}
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fprintf (stderr,"AMBE Straight XOR %d-bit Keystream: ", len);
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for (uint16_t i = 0; i < unpack_len; i++)
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fprintf (stderr, "%02X", ks_bytes[i]);
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fprintf (stderr, " with Forced Application \n");
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state->straight_ks = 1;
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state->straight_mod = (int)len;
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END_KS:
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if (curr == NULL)
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fprintf (stderr, "Straight KS String Malformed! No KS Created!\n");
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} |