As long as we are talking modest amounts, saved from agreed allowances you can invest in this crypto-currency, and by modest I mean a few quid each month --- more than that will make the IP reconsider whether your allowances are too generous !
If they make money ( which is doubtful ) then that 'profit' will be treated as a windfall or extra income and be payable to the IVA according to your agreed terms in this regard.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk