Why cryptography?

Edward Snowden, whistleblower and former NSA contractor, wrote in a Q&A at The Guardian that "Encryption works. Properly implemented, strong cryptographic systems are one of the few things that you can rely on" when asked about privacy on the internet.

Privacy is recognized as a human right in the UN Declaration of Human Rights. Cryptography helps safeguard your privacy on the internet by protecting your online communication from eavesdropping, securing your private data from unauthorized access, and enabling authentication so you can prove your identity online. Yet, cryptography remains challenging to implement correctly—recent reports show that while over 95% of web traffic is now encrypted, nearly half of companies are concerned about keeping up with cryptographic changes, and more than half of sensitive cloud data is still left unencrypted. This highlights the ongoing need for better cryptography education among developers:

percent of web traffic now encrypted with HTTPS*

percent of companies are concerned about their ability to adapt to changes in cryptography*

percent of sensitive data stored in the cloud remains unencrypted*

Who use cryptography?

You have most likely used an application today that relied on cryptography to protect your privacy. For example, when you update an application on your computer, the application must verify that the received update is from the correct source and not a malicious one. Another example is online shopping and internet banking, where a successful eavesdropper could intercept your credit card and private banking information. To prevent this, the communication between you and the shop or bank (the website) must be encrypted, and you must identify yourself to gain access. Finally, many people depend on secure communication to protect their company's information from competitors, or because they live in a country where expressing their own opinions could put them at risk. In such cases, they also need a way to communicate anonymously.

Software updates

E-banking

Webpages

Communications

An introduction to cryptography

When Julius Caesar sent messages to his generals, he didn't trust his messengers. So he replaced every A in his messages with a D, every B with an E, and so on through the alphabet. Only someone who knew the "shift by 3" rule could decipher his messages.

And so we begin.*

Encryption

Signature

Additional