TOKYO (Reuters) - Digital currencies won't topple hard money printed by central banks any time soon, particularly in countries such as Japan with a solid, established financial infrastructure, a senior Bank of Japan official said on Tuesday.<div><a href="http://feeds.reuters.com/~ff/reuters/technologyNews?a=c7xaMIjaGWQ:uinSd4aX4sY:yIl2AUoC8zA"><img src="http://feeds.feedburner.com/~ff/reuters/technologyNews?d=yIl2AUoC8zA" border="0" /></a> <a href="http://feeds.reuters.com/~ff/reuters/technologyNews?a=c7xaMIjaGWQ:uinSd4aX4sY:V_sGLiPBpWU"><img src="http://feeds.feedburner.com/~ff/reuters/technologyNews?i=c7xaMIjaGWQ:uinSd4aX4sY:V_sGLiPBpWU" border="0" /></a> <a href="http://feeds.reuters.com/~ff/reuters/technologyNews?a=c7xaMIjaGWQ:uinSd4aX4sY:-BTjWOF_DHI"><img src="http://feeds.feedburner.com/~ff/reuters/technologyNews?i=c7xaMIjaGWQ:uinSd4aX4sY:-BTjWOF_DHI" border="0" /></a></div><img src="http://feeds.feedburner.com/~r/reuters/technologyNews/~4/c7xaMIjaGWQ" height="1" width="1" alt="" />