Abstract: A verifier for verifying the authenticity of a communication sent via a communications network from a first network component to a second network component including input means/apparatus arranged for receiving via the communications network an encrypted communication from a said first network component. The verifier has key means/apparatus operable to issue to a said second network component a key associated with the first network component on condition that the verifier has verified the encrypted communication to be decryptable using said key thereby to enable the second network component to decrypt encrypted communications from the first network component sent independently of the verifier apparatus.