TsigGenerate fills out the TSIG record attached to the message.

TsigGenerateByAlgorithm fills out the TSIG record attached to the message using a callback to implement the algorithm-specific generation.

TsigVerify verifies the TSIG on a message.

TsigVerifyByAlgorithm verifies the TSIG on a message using a callback to implement the algorithm-specific verification.

TSIG is the RR the holds the transaction signature of a message.