Four short visual lessons showing how encryption, hashing and digital signatures protect blockchain transactions.
Mission 1
Step 1
Alice needs to send a confidential business document to Bob. At the moment, the document is readable plaintext.
Plaintext is the original readable information before encryption.
Cryptography Missions is a free, self-paced interactive lesson for students who are beginning to study blockchain. Four short visual missions show how three building blocks of cryptography, namely encryption, hashing and digital signatures, protect a blockchain transaction.
The first mission uses a single shared secret key to encrypt a confidential document, which introduces symmetric encryption. The second mission replaces the shared key with a public lockbox, which introduces asymmetric encryption, where a public key and a private key play different roles. The third mission uses a fruit-shake analogy to explain hashing, in which data is turned into a fixed digital fingerprint that reveals whether the data has changed. The fourth mission shows how a digital signature connects a transaction to the private key that authorised it.
After the lesson, a learner should be able to explain what encryption, hashing and digital signatures each contribute, and to describe how blockchain uses hashes and signatures to verify and record authorised transactions.
The lesson is one of a set of companion teaching resources by Dr Mahmoud Elkhodr. It is licensed under CC BY 4.0, so educators may reuse and adapt it with attribution.
Protects confidentiality by making information unreadable without the correct key.
Creates a fixed digital fingerprint that reveals whether data has changed.
Connect data to the private key that authorised it.
Uses hashes and signatures to verify and record authorised transactions.