Additive manufacturing technologies enable various possibilities to create and modify the material composition and structure on a local level, but are often prone to undesired defects and inhomogeneities. This contribution makes use of such flaws to generate material-inherent, hidden codes and watermarks in metals for authentication and anti-counterfeiting applications. By controlled and random process variation, unique codes that can be read and authenticated by an eddy current device were produced with the processes of laser powder bed fusion (L-PBF) and laser directed energy deposition (L-DED). Two approaches are presented: First, volumetric, porous structures with a defined shape are manufactured with L-PBF. Second, coatings are fabricated by L-DED with alternating process parameters, leading to local deviations of the magnetic permeability. This non-deterministic coding approach generates a distinctive material structure that triggers high signal amplitudes in the eddy current measurement. Counterfeiting becomes impossible due to the irreproducible melt pool dynamics. Statistical hypothesis testing proves that the system is able to prevent false acceptance or rejection of a code with a certainty of 500 million to one. A low-cost setup for a novel locking system demonstrates that a code can be sensed reliably within one second.

增材制造技术使在本地创建和修改材料成分和结构的各种可能性成为可能，但通常容易出现不良缺陷和不均匀性。这种贡献利用这些缺陷在金属中生成材料固有的隐藏代码和水印，以用于身份验证和防伪应用。通过受控的随机过程变化，可以通过激光粉末床熔合（L-PBF）和激光定向能量沉积（L-DED）的过程产生可以由涡流设备读取和验证的唯一代码。介绍了两种方法：首先，使用L-PBF制造具有定义形状的体积多孔结构。其次，通过具有交替的工艺参数的L-DED制造涂层，从而导致磁导率的局部偏差。这种非确定性的编码方法会产生独特的材料结构，该结构会在涡流测量中触发高信号幅度。由于无法复制的熔池动力学，伪造变得不可能。统计假设检验证明，该系统能够防止对代码的5亿个错误接受或拒绝。新型锁定系统的低成本设置表明，可以在一秒钟之内可靠地检测到密码。统计假设检验证明，该系统能够防止对代码的5亿个错误接受或拒绝。新型锁定系统的低成本设置表明，可以在一秒钟之内可靠地检测到密码。统计假设检验证明，该系统能够防止对代码的5亿个错误接受或拒绝。新型锁定系统的低成本设置表明，可以在一秒钟之内可靠地检测到密码。