Advantages and disadvantages Hashcash

the hashcash system has advantage on micropayment proposals applying legitimate email no real money involved. neither sender nor recipient need pay, administrative issues involved micropayment systems entirely avoided.

on other hand, hashcash requires potentially significant computational resources expended on each e-mail being sent, difficult tune ideal amount of average time 1 wishes clients expend computing valid header. can mean sacrificing accessibility low-end embedded systems or else running risk of hostile hosts not being challenged enough provide effective filter spam.

hashcash simple implement in mail user agents , spam filters. no central server needed. hashcash can incrementally deployed—the hashcash header ignored when received mail clients not understand it.

one plausible analysis concluded 1 of following cases likely: either non-spam e-mail stuck due lack of processing power of sender, or spam e-mail bound still through. examples of each include, respectively, centralized e-mail topology (like mailing list), in server send enormous amount of legitimate e-mails, , botnets or cluster farms spammers can increase processing power enormously.

most of these issues may addressed. e.g., botnets may expire faster because users notice high cpu load , take counter-measures, , mailing list servers can registered in white lists on subscribers hosts , relieved hashcash challenges. represent serious obstacles hashcash deployment remain addressed.

another projected problem computers continue faster according moore s law. difficulty of calculations required must increased on time. however, developing countries can expected use older hardware, means find increasingly difficult participate in email system. applies lower-income individuals in developed countries cannot afford latest hardware.