What is the critical security requirement for *key provisioningin a multi-tenant OTP system where each tenant manages its own set of users and secrets?

The critical security requirement for key provisioning in a multi-tenant One-Time Password (OTP) system, where each tenant manages its own users and secrets, is strict cryptographic isolation of tenant-specific cryptographic keys and secrets throughout the entire provisioning process. An OTP system generates and validates one-time passwords, which are temporary credentials typically derived from a shared secret, often called a seed, that is known to both the user's authenticator (e.g., a mobile app or hardware token) and the server validating the password. Key provisioning is the secure procedure of creating, distributing, and installing these unique cryptographic seeds for each user or authenticator within the system. In a multi-tenant environment, a single software instance or infrastructure serves numerous distinct customers, referred to as tenants. Each tenant operates independently with their own set of users and sensitive data, crucially including their unique OTP cryptographic seeds. The paramount security concern is to absolutely prevent the cryptographic secrets of one tenant from being accessed, compromised, or utilized by any other tenant sharing the same underlying system. This strict cryptographic isolation dictates that the seeds belonging to Tenant A must be entirely inaccessible to Tenant B, whether these seeds are being transmitted during their initial setup or when they are stored within the system. For example, when provisioning an OTP authenticator for a user belonging to Tenant X, the secret seed assigned to that authenticator must be generated, securely transferred, and stored in a manner that is cryptographically distinct and irretrievable by a user or process associated with Tenant Y. This isolation is typically achieved through robust mechanisms such as employing unique tenant-specific encryption keys to protect data at rest and in transit, utilizing secure, authenticated channels for key distribution, and leveraging hardware security modules (HSMs) or secure enclaves to enforce logical and physical separation for key storage and cryptographic operations, thereby ensuring that no cross-tenant secret leakage can occur.