Method decrypt_model

lite/src/decryption/aes_decrypt.h:8–30

class AESDcryption {
public:
    static std::vector<uint8_t> decrypt_model(
            const void* model_mem, size_t size, const std::vector<uint8_t>& key) {
        mbedtls_aes_context ctx;
        mbedtls_aes_init(&ctx);
        mbedtls_aes_setkey_dec(&ctx, key.data(), 256);

        auto data = static_cast<const uint8_t*>(model_mem);
        //! first 16 bytes is IV
        uint8_t iv[16];
        //! last 8 bytes is file size(length)
        auto length_ptr = data + size - 8;
        size_t length = 0;
        for (int i = 0; i < 8; i++) {
            length |= length_ptr[i] << (8 * (7 - i));
        }
        std::copy(data, data + 16, iv);
        auto output = std::vector<uint8_t>(size - 24);
        mbedtls_aes_crypt_cbc(
                &ctx, MBEDTLS_AES_DECRYPT, size - 24, iv, data + 16, output.data());
        mbedtls_aes_free(&ctx);
        output.erase(output.begin() + length, output.end());
        return output;
    }

    static std::vector<uint8_t> get_decrypt_key() {
        std::vector<uint8_t> key(32);