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Fix ciphertext length handling in BLE advertisement #2

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Fix ciphertext length handling in BLE advertisement #2

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10 changes: 7 additions & 3 deletions components/bthome/bthome.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -450,15 +450,19 @@ void BTHome::build_advertisement_data_() {
size_t ciphertext_len = 0;

if (this->encrypt_payload_(plaintext, measurement_len, ciphertext, &ciphertext_len)) {
memcpy(this->adv_data_ + measurement_start, ciphertext, ciphertext_len);
pos = measurement_start + ciphertext_len;
size_t actual_ciphertext_len = ciphertext_len - 4;

memcpy(this->adv_data_ + measurement_start, ciphertext, actual_ciphertext_len);
pos = measurement_start + actual_ciphertext_len;

// Add counter (4 bytes, little-endian)
this->adv_data_[pos++] = this->counter_ & 0xFF;
this->adv_data_[pos++] = (this->counter_ >> 8) & 0xFF;
this->adv_data_[pos++] = (this->counter_ >> 16) & 0xFF;
this->adv_data_[pos++] = (this->counter_ >> 24) & 0xFF;

memcpy(this->adv_data_ + pos, ciphertext + actual_ciphertext_len, 4);
pos += 4;

this->counter_++;
}
}
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