Veins in the back of your hand are as unique as fingerprints and can be used to identify you without specialist hardware
Source:
https://www.newscientist.com/article/2267502-ai-can-use-the-veins-on-your-hand-like-fingerprints-to-identify-you/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home