1. A computer-based system securely transmitting and authenticating a transaction input by a user while retaining the anonymity of the user with respect to content of the transaction, comprising: a first device, where the content of the transaction is input and submitted to a second device; the second device encoding the content of the transaction that is input at the first device with a code key K Vsi , sending the content of the transaction that is encoded with the code key K VSi to the first device, the first device generating a first message by further encoding the content of the transaction that is encoded with the code key K VSi with a respective UPTF-SAS key, and the second device generating a second device encoded message by further encoding the content of the transaction that is encoded with the code key K VSi with a respective UPTF-SAS key; a third device receiving the encoded messages of the first and the second device, decoding the received encoded messages to authenticate an identity of the user of the first device, matching the decoded messages to authenticate an occurrence of the transaction, and forwarding the encoded content of the transaction that is encoded with the code key K VS to a fourth device; and the fourth device receiving the encoded content of the transaction encoded with the code key K VSi and using the code key K VSi to determine content of the transaction input by the user of the first device.