AutoCrypt Security Fuzzer is a fuzz testing tool designed for automotive system environments. The tool uses fuzzing algorithms and test cases built on Unified Diagnostics Services (UDS) structures, with support for CAN, Wi-Fi, Bluetooth LE, and Ethernet protocols. The software employs a logical test case modeler to generate test cases based on the protocol and specifications of the test target, ensuring only relevant test cases that may impact the targets are created. It uses diagnostic services with judgment logic to determine test pass or fail status. When abnormal responses occur, the tool performs automatic ECU status recovery by inputting ECU reset or DTC clear commands to restore the ECU to its original state for continuous testing. The solution supports hardware-in-a-loop simulations for testing during early vehicle development stages and provides testing coverage for automotive security validation.