• Recently, Bertino, Shang and Wagstaff proposed a time-bound hierarchical key management scheme for secure broadcasting. Their scheme is built on elliptic curve cryptography and implemented with tamper-resistant devices. • Tamper resistant device is a secure computer system is ensuring that various cryptographic keys can be accessed only by their intended user (s) and only for their intended purposes. • An appropriate way to protect keys is to store them in a tamper-resistant device. • In this paper, we present two collusion attacks on Bertino-Shang-Wagstaff scheme. • The first attack does not need to compromise any decryption device, while the second attack requires to compromise single decryption device only. Both attacks are feasible and effective.