how to send message digest alongwith the actual message over the network

Let E=encrypt(msg) D=digest(E)

If I send E+D to the peer. How is the peer supposed to know that it needs to split the incoming message at E and calculate its digest and verify against D.

Should the final msg contain some kind of length parameter or a开发者_JS百科 delimiter

There's no magic mechanism to add signatures independent of protocol. Each network protocol that allows for digital signatures, or digests, or encryption, does so differently.

For example:

http://en.wikipedia.org/wiki/WS-Security