A single decryption engine is used for decrypting a plurality of encrypted transport streams. Packets in each of the plurality of encrypted transport streams are tagged with a tag value to indicate their origin stream. The tagged packets from the plurality of encrypted transport streams are merged into a merged transport stream. The packets in the merged transport stream are decrypted with the decryption engine to produce a decrypted merged transport stream. The decrypted merged transport stream is split into a plurality of decrypted transport streams, equal in number to the plurality of encrypted transport streams, by routing packets in the decrypted merged transport stream to specific decrypted transport streams according to their tag value. A null-packet padding technique, a gapped-clock technique and a multi-port static RAM controller technique are disclosed.