INFORMATION-THEORETIC BOUNDS FOR AUTHENTICATION CODES AND BLOCK-DESIGNS

Authentication codes with secrecy and with splitting are investigated. An information-theoretic lower bound for the probability of successfu l deception for a spoofing attack of order r is obtained. The conditio n necessary on authentication codes to achieve the lower bound is dete rmined as a single simple requirement. Based on the simplicity of the result a construction, by use of so-called partially balanced t-design s, for authentication codes that can achieve the lower bound is sugges ted.