Abstract: An apparatus, a method and a computer program product for use when converting message information from a first format to a second format in packet transmitting systems.

Abstract: An apparatus, method and a computer program product for use as a key generator in conversion of message information from a first format into a second format, a first cipher unit (930) is arranged having a first cipher key input (908) and a data output (910) for outputting a data stream generated dependent on a first cipher key (EKEY) input via said first cipher key (908). A second cipher unit (910) having a plaintext input (901), a second cipher key input (903) and a ciphertext output (902) is via said second cipher key input (903) communicatively coupled to said data output (910) of the first cipher unit (930) for receiving a second cipher key (IKEY) in the shape of said data stream; and said first cipher unit (930) being arranged to perform, dependent on a predetermined rule, a renewed generation of a data stream for use as said second cipher key.