## The blockchain would not exist without cryptography

In recent decades, computer technology has transformed the way I store and share my information. However, this progress also comes with significant risks – cyber theft, data manipulation, unauthorized access. To address this issue, we have leveraged cryptography – the science of converting readable data into an unreadable form that only authorized parties can decrypt.

Cryptography is not a new invention. Even before the digital revolution, people were encoding messages to protect them from unwanted eyes. However, with the advent of computers, this ancient practice has evolved into a powerful mathematical tool capable of safeguarding critically important information in a global network.

### Why is cryptography so critical for blockchain?

Modern cryptography uses complex mathematical algorithms and computations to provide three key things:

**Confidentiality** – the transformation of plaintext into ciphertext, readable only with the correct key. When Alice sends 2 bitcoins to Bob, the transaction is secured in such a way that only the two of them can confirm the transfers.

**Authenticity** – ensuring that the message is genuinely from the sender. Digital signatures play a central role, ensuring that each user can spend only their own cryptocurrencies and that each coin is spent exactly once.

**Integrity** – confirmation that the data has not been altered. In the Bitcoin protocol, this is achieved through a specialized function called Hashcash, which utilizes the cryptographic algorithm SHA-256.

### How cryptography powers the decentralized economy

Every blockchain system, including Bitcoin, relies on cryptographic proofs to function as both a public and secure ledger. These proofs allow the network to verify each transaction without the need for a central authority.

The mining process, governed by the proof-of-work mechanism, is based precisely on cryptography. It not only secures the network but also validates transactions and generates new coins, all while remaining cryptographically protected.

Cryptography transforms the way we verify information and manage digital assets. It is the foundation upon which all decentralized systems are built and enables the secure exchange of value on a public network, without intermediaries.