target="NewWindow">draft-jennings-sip-hashcash-01
One of the techniques used in SPAM
prevention and various solutions for denial of service attacks is to force the
SIP client requesting a service to perform a calculation that limits the rate
and increases the cost of the request. This draft defines a way to allow a UAS
to ask the UAC to compute a computationally expensive hash based function and
present the result to the UAS. Although the computation is expensive for the UAC
to compute, it is cheap for the UAS to verify. The solution also allows for
proxies to compute and check the puzzle on behalf of the UAC or
UAS.
prevention and various solutions for denial of service attacks is to force the
SIP client requesting a service to perform a calculation that limits the rate
and increases the cost of the request. This draft defines a way to allow a UAS
to ask the UAC to compute a computationally expensive hash based function and
present the result to the UAS. Although the computation is expensive for the UAC
to compute, it is cheap for the UAS to verify. The solution also allows for
proxies to compute and check the puzzle on behalf of the UAC or
UAS.