A method, a computer system, and a computer program product for authenticating a transaction are provided. An authentication system receives the transaction over a particular channel of a plurality of support channels. A risk score is determined for the transaction based on a number of contextual risk factors. An authentication scheme is determined from a number of authentication schemes for authenticating an identity of the user within an authentication context. The authentication scheme is determined based on the particular channel and the risk score. In response to successfully authenticating the identity of the user within the authentication context, the authentication system determines whether the transaction is a permitted transaction based on an assurance level associated with the authentication context. In response to determining that the transaction is the permitted transaction, the transaction is authenticated.