The valid methods for authenticating users for access into Snowflake include federated authentication, key-pair authentication, and OAuth. Federated authentication allows users to log in using credentials from a trusted identity provider. Key-pair authentication uses a pair of cryptographic keys for identity verification. OAuth is an open standard for access delegation, commonly used as a way to grant websites or applications limited access to a user's information. SCIM, TLS 1.2, and OCSP authentication are not valid methods for user authentication in Snowflake.