Blockchains and cryptocurrencies in IoT

Blockchains are public, digital, and decentralized ledgers or cryptocurrency transactions. The original cryptocurrency blockchain was Bitcoin but there are over 700 new currencies on the market such as Ethereum, Ripple, and Dash. The power of a blockchain is that there is no single entity controlling the state of transactions. It also forces redundancy in the system by ensuring everyone using a blockchain also maintains a copy of the ledger. Assuming there is no inherent trust in blockchain participants, the system must live in consensus. 

A good question to ask is if we have solved identity management and security with asymmetric cryptography and key exchanges, why are blockchains needed to exchange data or currency?  This is not enough for the exchange of money or data of value. One thing to note is that since the inception of information theory, when two devices communicate, Bob and Alice, they send a message or a bit of data. That information is...