AbstractBroadcast encryption is a key‐distribution technique for sending encrypted messages to arbitrary groups of users in public channels. When applied to large systems (e.g., pay‐TV), the existing symmetric‐key‐setting schemes usually exhibit high transmission costs; thus, numerous efforts have been made to enhance the transmission performance. However, tremendous additional computation cost or storage size requirements are often necessary. In this paper, a symmetric‐key‐setting scheme, called balanced double subset difference, and its variant, BDSDλ, are proposed. By enlarging the subset collection of the subset difference scheme with special subsets, called balanced subsets, the proposed schemes retain the excellent computational performance of subset difference and offer the capability of reducing transmission costs with a reasonable storage requirement. Copyright © 2014 John Wiley & Sons, Ltd.