The sender device 820 may transmit a public key request 910 to the key servers 243. The public key request 910 may identify the recipient device 825-1 for which a public key is requested. The key servers 243 may return a particular recipient public key 920 from the recipient public key upload 910 to the sender device 820 in response to the public key request 910. It will be appreciated that the submission of a recipient public key upload 910 to the key servers 243 and the retrieval of the recipient public key 920 from the key servers 243 may comprise communication with a particular one or more key servers of a plurality of key servers 243 rather than the direct involvement of all of the plurality of key servers 243.