System and method for acoustic two factor authentication

A system for two-factor authentication over a link not constrained to be secure, comprising:

• at least one portable token generating at least one wireless signal representing a digitally signed message;
• at least one receiver receiving the wireless signal and a PIN, the PIN being received separately from the wireless signal, the receiver encrypting the signed message with the PIN to render an encrypted signed message;
• and
• at least one authorizing computer receiving at least the encrypted signed message over the link, the authorizing computer accessing the PIN and a confidential public key to attempt to verify the signed message.

A system for authentication including an authorizing computer accessing at least a PIN and a confidential public key and communicating over a link with at least one receiver remote from the computer, the communication link not being constrained to be secure, the system comprising:

• means for receiving, at the receiver, at least one wireless signal representative of at least one digital signature produced from a private key, the receiver transforming the wireless signal to a signature signal;
• means for receiving, at the receiver, the PIN;
• and
• means for encrypting the signature signal with the PIN to render an encrypted signature signal, wherein the encrypted signature signal is sent to the authorizing computer over the link for verification of the signature using the PIN and confidential public key.