Chapter 4. Cryptography and Mechanics Behind Blockchain

The use of blockchain hinges on cryptography. Numeric cryptography can be regarded as a recent invention, with the ciphers of the past relying on exchanging words for words and letters for letters. As we'll see, modern cryptography is a very powerful tool for securing communications, and, importantly for our topic, determining the provenance of digital signatures and the authenticity of digital assets. 

In this chapter, the following topics will be covered:

• Principles of security
• Historical perspective – classical cryptography
• Cryptographic signatures
• Hashing