A method for processing a communication data item. The communication data item is divided into at least two unencrypted packets to be encrypted. Each encrypted packet is generated from a corresponding unencrypted packet. Each unencrypted packet has a packet header and plaintext data. The packet header has an identifier field that includes a packet identifier. The packet identifier is identical for all unencrypted packets. Generating an encrypted packet for each unencrypted packet includes: determining a vector identifier from the identical packet identifier, wherein the vector identifier is associated with the identical packet identifier; ascertaining an initial vector from the vector identifier; and forming an encrypted packet header by inserting the vector identifier into a first portion of the packet header and encrypting a second portion of the packet header through use of the initial vector. The encrypted packets are subsequently decrypted and combined to reconstruct the communication data item.