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 receiving the content of the transaction input at the first device and transmitting, to a second device, the transaction content including information identifying the first device and the second device; wherein the second device encoding the transaction content input at the first device with a code key K VSi , sending the transaction content that is encoded with the code key K VSi to the first device, the first device generating a first message by further encoding the information identifying the first and second devices and the transaction content encoded with the code key K VSi with an independently generated first device changing key derived from both a user input non-transmitted parameter and a first device parameter generated for each transaction based upon a stored first device parameter, and the second device generating a second device encoded second message by encoding the transaction content encoded with the code key K VSi and the information identifying the first and second devices, with an independently generated second device key; and a third device receiving the encoded second message from the second device and receiving the encoded first message of the first device, decoding only the encoding by the first and second device keys of the received encoded first and second messages based upon the third device independently generating the respective first and second device keys to: authenticate an identity of the user of the first device and authenticate the first device, authenticate the second device and authenticate an occurrence of the transaction by matching the decoded messages of the first and second devices based upon the information identifying the first and second devices for confirming input of the transaction content to involve intended first and second devices, and forwarding the encoded transaction content encoded with the code key K VSi to a fourth device; wherein the fourth device receiving the encoded transaction content encoded with the code key K VSi and using the code key K VSi to determine the transaction content input by the user of the first device.