The previous step provided a gentle introduction to asymmetric cryptography. It also noted that blockchain uses public cryptographic keys as account numbers and uses the “public to private” approach of asymmetric cryptography to transfer ownership among accounts. However, that was only half of the story. Blockchain needs to ensure that only the lawful owner can transfer their property to other accounts. This is where the concept of authorization comes into play. Hence, this step explains how asymmetric cryptography is used in blockchain to authorize transactions. In particular, this step focuses on the concept of digital signatures, which use the “private to public” approach of asymmetric cryptography.