We started this chapter with the introduction of asymmetric key cryptography. We discussed various constructs such as RSA and ECC. We also performed some experiments using OpenSSL to see that how theoretical concepts can be implemented practically. After this, we discussed hash functions in detail along with its properties and usage. Next, we covered concepts such as Merkle trees, which are used extensively in blockchain and, in fact, are at its core. We also presented other concepts such as Patricia trees and hash tables.
In the next chapter, we will present Bitcoin, which is the first blockchain invented in 2009 with the introduction of Bitcoin cryptocurrency.