How to Use Your Brain for Cryptography Without Trustworthy Machines

In this work, we study cryptosystems that can be executed securely without fully trusting all machines, but only trusting the user’s brain. This paper focuses on the signature scheme. We first introduce a new concept called “server-aided in-brain signature,” a cryptographic protocol between a human brain and multiple servers to sign a message securely even if the servers and devices used to access the servers are not completely trusted. Second, we propose a concrete scheme that is secure against mobile hackers in servers and malware infecting users’ devices.