update

2026-05-18 22:59:45 +02:00
parent aed00ceda2
commit 77c9d4a4d5
10 changed files with 1185 additions and 119 deletions
@@ -0,0 +1,130 @@
+#include "servergprs.h"
+
+#include "psa_crypto_driver_esp_aes_gcm.h"
+
+char linebufIn[1024];
+char *linebufInPtr = linebufIn;
+
+#define MAX_FRAME 512
+
+static uint8_t rx_buf[MAX_FRAME];
+static size_t rx_len = 0;
+static uint16_t expected_len = 0;
+static int state = 0;
+
+void process_encrypted_frame(uint8_t *data, size_t len)
+{
+    // layout:
+    // [4B device_id][4B counter][12B nonce][ciphertext...][16B tag]
+
+    if (len < 36) return;
+
+    uint8_t *device_id = data;
+    uint8_t *counter   = data + 4;
+    uint8_t *nonce     = data + 8;
+    uint8_t *cipher    = data + 20;
+    size_t cipher_len  = len - 36;
+    uint8_t *tag       = data + len - 16;
+
+    uint8_t plaintext[512];
+    size_t plaintext_len = 0;
+
+    psa_key_attributes_t attr = PSA_KEY_ATTRIBUTES_INIT;
+
+    psa_status_t st = esp_crypto_aes_gcm_decrypt(
+        &attr,
+        shared_key,
+        sizeof(shared_key),
+        PSA_ALG_GCM,
+        nonce, 12,
+        NULL, 0,
+        cipher, cipher_len,
+        plaintext, sizeof(plaintext),
+        &plaintext_len
+    );
+
+    if (st != PSA_SUCCESS) {
+        return;
+    }
+
+    handle_message(plaintext, plaintext_len);
+}
+
+void send_secure_packet(uint8_t *msg, size_t msg_len)
+{
+    uint8_t nonce[12];
+    generate_random(nonce, 12);
+
+    uint8_t cipher[512];
+    size_t cipher_len = 0;
+
+    uint8_t tag[16];
+    size_t tag_len = 0;
+
+    esp_crypto_aes_gcm_encrypt(
+        &attr,
+        shared_key,
+        sizeof(shared_key),
+        PSA_ALG_GCM,
+        nonce, 12,
+        NULL, 0,
+        msg, msg_len,
+        cipher, sizeof(cipher),
+        &cipher_len
+    );
+
+    // build frame:
+    // [LEN][NONCE][CIPHER][TAG]
+
+    uint16_t total =
+        12 + cipher_len + 16;
+
+    uint8_t out[600];
+
+    out[0] = (total >> 8) & 0xFF;
+    out[1] = total & 0xFF;
+
+    memcpy(out + 2, nonce, 12);
+    memcpy(out + 14, cipher, cipher_len);
+    memcpy(out + 14 + cipher_len, tag, 16);
+
+    sim800_tcp_send(out, total + 2);
+}
+
+
+void tcp_on_byte(char c)
+{
+    switch (state)
+    {
+        // WAIT FOR LENGTH (2 bytes)
+        case 0:
+            rx_buf[rx_len++] = c;
+            if (rx_len == 2)
+            {
+                expected_len = (rx_buf[0] << 8) | rx_buf[1];
+                rx_len = 0;
+
+                if (expected_len > MAX_FRAME) {
+                    rx_len = 0;
+                    state = 0;
+                    return;
+                }
+
+                state = 1;
+            }
+            break;
+
+        // READ FRAME
+        case 1:
+            rx_buf[rx_len++] = c;
+
+            if (rx_len >= expected_len)
+            {
+                process_encrypted_frame(rx_buf, rx_len);
+
+                rx_len = 0;
+                state = 0;
+            }
+            break;
+    }
+}