KerPass EPHEMSEC One-Time Password Algorithm

This document specifies EPHEMSEC, an algorithm for generating one- time passwords (OTPs) and one-time keys (OTKs). Unlike traditional OTP algorithms that rely solely on static shared secrets, EPHEMSEC uses public key cryptography, which simplifies secure deployment on authentication servers. EPHEMSEC also supports binding the generated OTP/OTK to contextual data. When this context is obtained and injected by a trusted agent, the resulting codes can be made resistant to phishing and man-in-the-middle attacks. Finally, EPHEMSEC includes a built-in time synchronization mechanism that embeds a synchronization hint into the generated output. This allows both parties to deterministically derive the same OTP/OTK value without requiring trial-and-error validation, enabling compatibility with protocols such as Password Authenticated Key Exchange (PAKE) and TLS with Pre-Shared Key (TLS-PSK) that require exact secret agreement.