If you want to understand cryptocurrencies, I suggest you first learn about normal currencies.
I love this old book on money:
http://mises.org/books/theory_money_credit/contents.aspx.
Ludwig von Mises was one of the most prominent members of the Austrian School of Economics.
I find the book easy to comprehend.
Keynes liked it:
“The first book deals with the meaning, place, and function of money; the second with the value of money, the problem of measuring it, and the social consequences of variations in it; and the third with the relation of bank-money, of notes, and of discount policy to the theory of money. With the exception of the section on the value of money, where Dr. von Mises is too easily satisfied with mere criticism of imperfect theories, there is a great deal on every one of these topics very well worth reading. Perhaps the third book is, on the whole, the best.” (Keynes 1914: 417).