Systems and methods are provided that include: accessing implicit authentication data from a possession factor associated with an authorized user; at the possession factor or at an authentication platform: generating a possession confidence level using the implicit authentication data, the possession confidence level being one of a plurality of possession confidence levels, the possession confidence level indicating a likelihood that the possession factor is possessed by the authorized user; identifying, among a plurality of varying authentication requirements, an authentication requirement for the transaction based on the possession confidence level, the authentication requirement defines a process or action to prove authority to perform the transaction or a process or action to prove an identity of a user attempting to perform the transaction; and implementing the authentication requirement for the transaction.