Cryptography is the study of how to secure communication, and it's about two really important things: 密码学是一门关于保障通信安全的学科，其中有两件特别重要的事：

masking information so it can be hidden in plain sight, and verifying a piece of information's source. 为信息加密，使之能隐藏在简单的形式下；核实一小部分的信息来源。

Cryptography underpins so many of the systems around us.  密码学是存在于我们周围很多系统的基础。

And it's so powerful that at times the US government has actually classified it as a weapon. 由于密码学是如此的有用，美国政府甚至把它列为一种武器。

During World War II, breaking cryptosystems like Enigma was critical to decoding enemy transmissions and turning the tide of the war. 在二战时期，破译类似恩尼格码的密码在解译敌方通信中起着至关重要的作用，甚至改变了战争的大潮。

Today, anyone with a modern web browser is running a pretty sophisticated cryptosystem. 如今，任何人都在用的浏览器，也是由一套复杂的密码系统支持运行的。

It's what we use to secure our interactions on the Internet. 它保障了我们在使用网络时的安全性。

It's what makes it safe for us to type our passwords in and to send financial information to websites. 在输入密码以及发送金融信息时，它也能保障我们的安全。

So what the banks used to give us -- trustworthy digital money transfer 那我们熟知的银行提供了什么服务呢--可靠的数字货币交易

we can now get with a clever application of cryptography.  当密码学投入使用后。

And this means that we don't have to rely on the banks anymore to secure our transactions.  这意味着我们不再需要依赖于银行去确保我们交易的安全性，

We can do it ourselves. 我们自己也可以保障我们的交易安全。

Bitcoin is based on the very same idea that the Yap used, this collective global knowledge of transfers. 比特币的概念和雅浦币类似，全球交易认知的集合。

In Bitcoin, I spend by transferring Bitcoin, and I get paid when someone transfers Bitcoin to me. 在比特币世界里，我花费的是比特币，收入也以比特币的形式获得。