Authentication system and portable medium for authentication

An authentication system comprising:

• a measuring portion that radiates terahertz waves to a portable medium for authentication including materials having a characteristic oscillation frequency in a terahertz frequency band while scanning in a two-dimensional manner, measures a two-dimensional distribution of a spectrum, and outputs a first measurement spectrum two-dimensional distribution that is a measurement result;
• a characteristic spectrum database which stores a characteristic spectrum of the materials;
• a discriminating portion that discriminates the materials that are included in the portable medium for authentication based on the first measurement spectrum two-dimensional distribution and the characteristic spectrum and acquires a discrimination result, the discriminating portion judging a permutation in a two-dimensional spatial relation of the materials determined by the discrimination result;
• an authentication database which stores at least a plurality of permutations of materials that are included in the portable medium for authentication, the permutations differing from one another, a combination of materials which constitute one of the permutations being the same as a combination of materials which constitute each one of the other permutations;
• and
• an authenticating portion that determines whether the permutation judged by the discriminating portion is the same as any one of the permutations stored in the authentication database, the authenticating portion outputting an authentication signal upon determining that the permutation judged by the discriminating portion is the same as any one of the permutations stored in the authentication database.