Patent ID: 8315601

Claim:
A mobile device configured to process a message comprising a plurality of encrypted attachments addressed to a plurality of recipients received from a sender via one or more remote servers, wherein the mobile device comprises a processor and memory, and wherein the processor is configured to perform acts comprising: receiving, from the one or more remote servers, data associated with the message, wherein the one or more remote servers are configured to initially withhold transmission of each encrypted attachment of the plurality of encrypted attachments to the mobile device until a request for the attachment is made by the mobile device, and wherein the data received from the one or more remote servers identifies an attachment structure for the message and comprises, for each of the plurality of encrypted attachments, an encrypted session key for each of the plurality of recipients; outputting the attachment structure; wherein for each of the plurality of encrypted attachments, the encrypted session key for the recipient associated with the mobile device is decryptable with a key accessible to the mobile device but not to the one or more remote servers, and the encrypted session key for recipients not associated with the mobile device cannot be decrypted with the key accessible to the mobile device but not to the one or more remote servers; receiving an attachment request via a user interface of the mobile device, the attachment request identifying a specific encrypted attachment of the plurality of encrypted attachments; decrypting the encrypted session key that is for the specific encrypted attachment and that is for the recipient associated with the mobile device to produce a decrypted session key; transmitting the decrypted session key with the attachment request to the one or more remote servers, wherein the one or more remote servers are configured to decrypt the specific encrypted attachment using the decrypted session key and to transmit data associated with the specific encrypted attachment in decrypted form to the mobile device; and receiving data associated with the specific encrypted attachment in decrypted form from the one or more remote servers.