DMR TYT AP (PC4) Encryption Mode Support; #302

Above Commit is by Anonymous Submission;

include/dsd.h

@@ -986,6 +986,8 @@ typedef struct
   struct CODEC2 *codec2_1600; //M17 halfrate
   #endif
 
+  //tyt_ap=1 active  
+  int tyt_ap;
 } dsd_state;
 
 /*

include/pc4.h

@@ -0,0 +1,95 @@
+#include <stdint.h>
+#include <stddef.h>
+
+#ifndef TYT_AP
+#define TYT_AP
+
+#define nbround 254
+#define n1 264
+
+#define UNUSEDPC4(x)                       ((void)x)
+
+/* Structure holding all PC4 state variables */
+typedef struct {
+    short bits[49], temp[49];
+    uint8_t ptconvert;
+    uint8_t convert[7];
+    uint8_t perm[16][256];
+    uint8_t new1[256];
+    uint8_t array[49];
+    uint8_t array2[49];
+    uint8_t decal[nbround];
+    uint8_t rngxor[nbround][3];
+    uint8_t rngxor2[nbround][3];
+    uint8_t rounds;
+    uint8_t tab[256];
+    uint8_t inv[256];
+    uint8_t permut[3][3];
+    uint64_t bb;
+    uint64_t x;
+    uint8_t tot[3];
+    uint8_t l[2][3], r[2][3];
+    uint8_t y, totb;
+    uint32_t result;
+    uint8_t xyz, count;
+    uint8_t keys[16];
+    unsigned char array_arc4[256];
+    int i_arc4, j_arc4;
+    int x1, x2, i;
+    unsigned char h2[n1];
+    unsigned char h1[n1*3];
+} PC4Context;
+
+/* Global context accessible from all .c files */
+extern PC4Context ctx;
+
+/* Public API */
+void create_keys(PC4Context *ctx, unsigned char key1[], size_t size1);
+void pc4encrypt(PC4Context *ctx);
+void pc4decrypt(PC4Context *ctx);
+void binhex(PC4Context *ctx, short *z, int length);
+void hexbin(PC4Context *ctx, short *q, uint8_t w, uint8_t hex);
+static void u64_to_bytes_be(uint64_t val, unsigned char *out);
+
+/* Encrypt a 49-bit frame (original flow) */
+static void encrypt_frame_49(short frame_bits_in[49]) {
+    for (int i = 0; i < 49; i++) ctx.bits[i] = frame_bits_in[i];
+    for (int i = 0; i < 49; i++) ctx.temp[i] = ctx.bits[ctx.array[i]];
+    for (int i = 0; i < 49; i++) ctx.bits[i] = ctx.temp[i];
+    ctx.ptconvert = 0;
+    binhex(&ctx, ctx.bits, 48);
+    pc4encrypt(&ctx);
+    for (int q = 0; q < 6; q++) {
+        uint8_t w = (uint8_t)(q * 8);
+        hexbin(&ctx, ctx.bits, w, ctx.convert[q]);
+    }
+    ctx.bits[48] = (short)(ctx.bits[48] ^ ctx.totb);
+    for (int i = 0; i < 49; i++) ctx.temp[ctx.array2[i]] = ctx.bits[i];
+    for (int i = 0; i < 49; i++) ctx.bits[i] = ctx.temp[i];
+}
+
+/* Decrypt a 49-bit frame (original flow) */
+static void decrypt_frame_49(short frame_bits_in[49]) {
+    for (int i = 0; i < 49; i++) ctx.bits[i] = frame_bits_in[i];
+    for (int i = 0; i < 49; i++) ctx.temp[i] = ctx.bits[ctx.array2[i]];
+    for (int i = 0; i < 49; i++) ctx.bits[i] = ctx.temp[i];
+    ctx.ptconvert = 0;
+    binhex(&ctx, ctx.bits, 48);
+    pc4decrypt(&ctx);
+    for (int q = 0; q < 6; q++) {
+        uint8_t w = (uint8_t)(q * 8);
+        hexbin(&ctx, ctx.bits, w, ctx.convert[q]);
+    }
+    ctx.bits[48] = (short)(ctx.bits[48] ^ ctx.totb);
+    for (int i = 0; i < 49; i++) ctx.temp[ctx.array[i]] = ctx.bits[i];
+    for (int i = 0; i < 49; i++) ctx.bits[i] = ctx.temp[i];
+}
+
+/* Convert 64-bit integer to bytes (big-endian) */
+static void u64_to_bytes_be(uint64_t val, unsigned char *out) {
+    for (int i = 0; i < 8; i++) {
+        out[i] = (unsigned char)((val >> (56 - 8 * i)) & 0xFF);
+    }
+}
+
+#endif