Introduction In the digital age, where privacy and security are critical, cryptography plays a key role in ensuring secure communication and protecting sensitive data. When it comes to cryptocurrency, cryptography is the backbone of its functionality, privacy, and trustworthiness. But what exactly is cryptography, and how is it connected to cryptocurrencies like Bitcoin, Ethereum, and others? In this article, we will explore what is cryptography in cryptocurrency, how cryptocurrencies use cryptography, and the deep relationship between cryptography and blockchain.