SIGNATURE AND VERIFICATION METHOD, SIGNATURE GENERATION DEVICE, AND SIGNATURE VERIFICATION DEVICE

摘要

In NTRUSign scheme, provided are a signature generation device and a signature verification device capable of countering a transcript attack that obtains a secret key by analyzing a plurality of signed sentences (pairs of message data and a signature). The signature generation device calculates the hash-value vector (H) of message data, and adds a vector based on a secret distribution to the hash-value vector (H) of the message data to calculate a converted hash-value vector (H'). The signature generation device obtains, as a signature vector (S), a lattice point closest to the converted hash-value vector (H') in a lattice defined by a secret key base vector. The signature verification device determines whether the distance between the hash-value vector (H) of the message data and the signature vector (S) is within L' or not and, when the distance is within L', recognizes the message data as valid.