Abstract-The system that uses network coding is highly susceptible to pollution attacks, where a malicious node may pollute a small number of packets with the purpose of preventing the recipient nodes from reconstructing the original messages properly. Some schemes that use Message Authentication Code (MAC) have been proposed for resisting this attack. However, these schemes could be broken with probability 1/q, where q is the size of the underlying field. Although the trace function has already been used for constructing MACs for a higher security, it can only be used for single-generation distribution. This paper proposes a novel MAC-based scheme that also employs trace function. However, different from prior work, our scheme can be immediately used for secure multi-generation distribution. [2] has been applied to network for achieving the optimal throughput. However, it is susceptible to pollution attacks, where a malicious node injects corrupted packets into network, aiming at preventing the recipient from reconstructing the original file. Due to the way the packets are combined and transmitted, a small number of polluted packets can cause large-scale pollution propagation. To solve the problem, several public-key based schemes [5]-[8] and hybrid [14][15] schemes are proposed. In these schemes, the source node signs the packet using a private key. The recipients use the public key known to all the nodes to check the integrity of the packet. However, these schemes are based on expensive paring operations [5]- [7] or exponentiation operations over a large field [8], which makes these schemes not fast enough for online communication.
Keywords-To address the inefficiency of public-key based scheme, some efficient symmetric-key based [9]-[13] schemes are introduced. Le et al. [13] proposed an efficient message authentication code (MAC) based inter-session scheme which supports multi-generation communication. However, its security relies on the size of the underlying field, which means in standard network coding based environment, where the field size is usually