Methods and systems for consensus-based online authentication are provided. An encryption device may be authenticated based on an authentication cryptogram generated by the encryption device. The encryption device may transmit a request for security assessment to one or more support devices. The support devices may individually assess the encryption device, other security devices, and contextual information. The support devices may choose to participate in a multi-party computation with the encryption device based on the security assessments. Support devices that choose to participate may transmit one or more secret shares or partial computations to the encryption device. The encryption device may use the secret shares or partial computations to generate an authentication cryptogram. The authentication cryptogram may be transmitted to a decryption device, which may decrypt the authentication cryptogram, evaluate its contents, and authenticate the encryption device based on its contents.