Thousands of years ago in ancient China they used chopped segments of bamboo for authentication purposes as well. They would chop a bundle of stalks into two bu

Thousands of years ago in ancient China they used chopped segments of bamboo for authentication purposes as well. They would chop a bundle of stalks into two bundles, and one bundle would be held by a (regional) king and distributed to key checkpoints. Then they gave the other, matching, bundle to another kingdom with whom they wanted to communicate. Later when a messenger wanted to bring a message past a guard station, the messenger would prove their authenticity by presenting a segment of bamboo, which could then be matched up with a corresponding segment held by the guard station. Apparently this practice and specifically the splitting of the bamboo into two pieces for this purpose is mentioned in the ancient Chinese dictionary, the Shuowen (https://en.wikipedia.org/wiki/Shuowen_Jiezi https://en.wikipedia.org/wiki/Shuowen_Jiezi). Source: Lao Kan, Chü-yen Han-chien k'ao-shih (居延漢簡考釋) (Decipherment and Critical Studies of the Inscriptions on the Wooden Tablets from Chü-yen). Chungking: Academia Sinica, 1943-44. Ts'e 1-4, shih-wen, I, 81b-82b; ts'e 5-6, k'ao-cheng, I, 32a-34a, cited in Written on Bamboo and Silk: The Beginnings of Chinese Books and Inscriptions, by Tsuen-Hsuin Tsien, University of Chicago Press, 1962; in particular see pages 106 and 110.