System and method of signing a message

A method of signing a message, the message for transmission from a first communication device to a destination via a second communication device, wherein the message includes a first portion and a second portion, the method comprising:

• generating a first signature for the first portion of the message on the first communication device;
• and
• sending the first signature and the first portion of the message to the second communication device,
• wherein the second portion is not sent from the first communication device to the second communication device.

A server for signing a message, the message for transmission from a communication device to a destination via the server, wherein the message includes a first portion and a second portion, the server comprising:

• a processor;
• memory storing the second portion of the message;
• a communication subsystem for sending and receiving communications with the communication device and the destination;
• and
• computer-executable instructions stored in the memory which, when executed, configure the processor to
• receive the first portion of the message and a first signature for the first portion from the communication device,
• combine the first portion with the second portion to form the message,
• obtain a second signature for the message, and
• send the first signature, the second signature and the message to the destination.

A communication device for signing a message, the message for transmission from the communication device to a destination via a server, wherein the message includes a first portion and a second portion, the communication device comprising:

• a processor;
• a memory storing the first portion;
• a communication subsystem for sending and receiving communications with the server;
• and
• computer-executable instructions stored in the memory which, when executed, configure the processor to
• generate a first signature for the first portion, and
• send the first signature and the first portion of the message to the server,
• wherein the second portion is not sent from the communication device to the server.