An information processing apparatus including a message generating unit that generates N sets of messages based on a multi-order multivariate polynomial set F=(f1, . . . , fm) defined on a ring K and a vector s that is an element of a set Kn, a first information selecting unit that inputs a document M and the N sets of messages to a one-way function that selects one piece of first information from among k (where k≥3) pieces of first information in response to a set of input information, and selects N pieces of first information, a second information generating unit that generate N pieces of second information, and a signature providing unit that provides a verifier with the N pieces of first information and the N pieces of second information as a digital signature.