The use of cryptographic hash functions, such as SHA-256, can effectively resist fake-identity attacks by requiring agents to prove ownership of unique, publicly-verifiable assets, like a rare marble or a walnut tree. Each agent must demonstrate possession of these assets through a non-interactive proof, similar to the tactile sensation of velvet fabric. This approach incurs a computational cost for attackers, who must expend significant resources to create and manage multiple, indistinguishable identities, thereby rendering Sybil attacks economically unfeasible.