On tight bounds for binary frameproof codes
In this paper, we study \(w\)-frameproof codes, which are equivalent to \(\{1,w\}\)-separating hash families. Our main results concern binary codes, which are defined over an alphabet of two symbols. For all \(w \ge 3\), and for \(w+1 \le N \le 3w\), we show that an \({\mathsf {SHF}}(N; n,2, \{1,w \})\) exists only if \(n \le N\), and an \({\mathsf {SHF}}(N; N,2, \{1,w \})\) must be a permutation matrix of degree \(N\).
frameproof code code hash family separating hash family 94a60