Message Countersignatures

Sometimes a signed message requires a countersignature. For example, user A may send a signed-data message to user B, expecting B to confirm agreement with the terms contained in the document. User B decodes the message, reads the terms and, if in agreement, countersigns the message. The countersigned message is then sent back to user A. User A now knows, and can prove, that user B agreed to the terms.

The following table lists sections that contain procedure descriptions or C program examples of message countersigning.

Section	Contents
Message Functions	Lists the counter signature functions.
Countersigning a Message	Details the process of counter signing a message.
Verifying a Countersignature	Details the procedure for verifying a counter signature.
Verifying a Signed Message	Details a process for verifying the signature on a signed message.
Example C Program: Encoding and Decoding a CounterSigned Message	Sample C program that encodes and decodes a countersigned message.