Streaming Scan Network (SSN) enables high-throughput testing for complex SoCs under pin constraints, but exposes the IEEE 1687 (IJTAG) setup path to security vulnerabilities including unauthorized Segment Insertion Bit (SIB) control and replay attacks. Existing defenses suffer from static-key leakage or poor Physical Unclonable Function (PUF) reproducibility under Process-Voltage-Temperature (PVT) variations. This paper proposes a dynamic IJTAG authentication combining PUF majority sampling, Hamming(15,11) error correction, and Key Derivation Function (KDF) for per-session unlock. This approach significantly improves authentication reliability by eliminating the high false rejection rates of previous PUF-based methods while achieving robust security against unauthorized access, all while maintaining SSN test-data path integrity.