US Patent 10992665 User authentication using biometric representation of one-time passcodes

User authentication techniques are provided using biometric representations of one-time passcodes. An exemplary method comprises initiating a challenge to a user in connection with an authentication request by the user to access a protected resource, wherein the challenge comprises a biometric encoding of a one-time passcode using a dictionary; processing a biometric representation by the user in response to the challenge in accordance with the biometric encoding and wherein the processing comprises determining a likelihood that the biometric representation by the user in response to the challenge matches the biometric encoding in the challenge; and resolving the authentication request based on the likelihood. The biometric encoding comprises, for example, a vocal passphrase and/or instructions for the user to perform a specified manipulation to a biometric sample of the user.