From the research paper by Nishith Desai there is some basis for considering Bitcoin profits as capital gains. That much is the easy part. When you obtained the asset (earned / bought / mined / begged / borrowed / stole) there is a "cost of acquisition" in INR. When you sell there is a "Sale Price". The difference is your profit (Capital Gains) and taxed. That's the simplest principle. By 'Transaction History' I mean list down all the Bitcoin you sold in the last financial year. Then tell list down how you obtained those bitcoin, along with acquisition costs. Then you find the difference.
If you have mining "income" things get far more interesting, and you just need to apply some common sense in terms of what you can justify to the IT department if you are called for audit. For mining, cost of server and electricity may be considered as cost of acquisition - but god knows what the IT department will think of it... That is beyond the scope of this discussion as there are no precedents or authoritative rules on this. Safe to say this is a gray area and you are really on your own.
Disclaimer: I am not a qualified tax consultant.