...
You need a margin account with at least 1:100 leverage, alternatively you could trade with a smaller leverage on sites like Poloniex and Bitfinex.
...
I really don´t think that there is any exchange or trading site that offers 100:1 leverage with assets that are as
volatile as cryptocurrencies.
E.g. at Bitfinex maximum leverage is 3.3:1 , which is a far cry from 100:1 leverage.
Why would you need 100:1 leverage in the first place? There is serious money to be made with 3:1 or 5:1 leverage (which is possible
at Kraken).
True, SimpleFX offers up to 1:500 on Forex pairs for small accounts. BTC-E used to offer 1:10 for cryptos until they got shut down, but yeah with such volatility 1:3 is enough.
Poloniex is another one with 1:3 leverage.