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 from the persistent storage accessible to the server system; decrypting, by the server system, the encrypted version of the payload key 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 from the persistent storage accessible to the server system; decrypting, by the server system, the encrypted version of the payload key 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.