A method for secure communication of payload data from a server system to a destination system used by a recipient, wherein the recipient is associated with a key pair comprising a public key and a private key, the private key being stored, protected by a password or passphrase of the recipient, in a key repository of the server system , and wherein the method comprises: receiving, by the server system , the payload data to be communicated to the destination system ; determining, by the server system , a payload key; encrypting, by the server system , the payload data by a symmetric encryption method using the payload key to obtain an encrypted version of the payload data; encrypting, by the server system , the payload key by an asymmetric encryption method using the recipient's public key to obtain an encrypted version of the payload key; storing, by the server system , the encrypted version of the payload key in persistent storage accessible to the server system ; generating and sending, by the server system , a conveyance message to the destination system , the conveyance message comprising the encrypted version of the payload data; receiving, by the server system , a return message from the destination system , the return message comprising the recipient's password or passphrase; accessing, by the server system , the recipient's private key using the recipient's password or passphrase; accessing, by the server system , the encrypted version of the payload key (S) from the persistent storage accessible to the server system ; decrypting, by the server system , the encrypted version of the payload key (S) using the recipient's private key; and sending, by the server system , the payload key to the destination system via a secured communication channel to allow the destination system to decrypt the encrypted version of the payload data using the payload key; wherein the recipient's private key does not leave a trusted environment of the server system . receiving, by the server system , the payload data to be communicated to the destination system ; determining, by the server system , a payload key; encrypting, by the server system , the payload data by a symmetric encryption method using the payload key to obtain an encrypted version of the payload data; encrypting, by the server system , the payload key by an asymmetric encryption method using the recipient's public key to obtain an encrypted version of the payload key; storing, by the server system , the encrypted version of the payload key in persistent storage accessible to the server system ; generating and sending, by the server system , a conveyance message to the destination system , the conveyance message comprising the encrypted version of the payload data; receiving, by the server system , a return message from the destination system , the return message comprising the recipient's password or passphrase; accessing, by the server system , the recipient's private key using the recipient's password or passphrase; accessing, by the server system , the encrypted version of the payload key (S) from the persistent storage accessible to the server system ; decrypting, by the server system , the encrypted version of the payload key (S) using the recipient's private key; and sending, by the server system , the payload key to the destination system via a secured communication channel to allow the destination system to decrypt the encrypted version of the payload data using the payload key; wherein the recipient's private key does not leave a trusted environment of the server system . <EOS>