SYNCHRONISATION OF DECRYPTION KEYS IN A DATA PACKET TRANSMISSION SYSTEM

摘要

The transmission system according to the invention comprises a transmitter (10) and a receiver (14). The transmitter can transmit data packets, e.g. IP packets, to the receiver. These data packets comprise a header (24), e.g. an ESP header, and an encrypted data field (26). The data fields (26) can be decrypted in the receiver (14) by means of a changing decryption key (48). The header (24) comprises information (32) indicating a change of the decryption key (48). This information (32) may be included in the SPI field of an ESP header. In this way the receiver (14) can determine exactly when to start using a new decryption key (48).