Private user data is securely entered from a public location in a way that the private user data cannot be ascertained by observers. A voice agent generates vocal instructions for a user, instructing the user to enter response data. The vocal instructions are communicated to the user with a telephonic link, in a manner that is secure from observers of entry of the response data. The instructions implement an encryption function, which causes the private user data to be encrypted within the response data. The response data is entered by the user vocally into a telephone, or by pressing buttons on a telephone keypad, or by pressing keys on a computer keyboard. The response data entered by the user is received by a security agent, which ascertains the private user data from the response data, and which also determines the validity of the data.