In modern days, cryptography is a very important part of many aspects of our modern society―especially in the Internet: safe communication between websites needs to be ensured to keep 3rd parties from interfering, e.g.in the process of logging into a website or accessing online databases. (Important to 'normal' users is http-encryption. On safe websites, a lock-symbol can be found next to the address bar in the browser, which also reveals more information regarding the encryption can be obtained) Thanks to Prof Zumbrägel and his talk "Public-Key Cryptography for Dummies", we had the opportunity to gain insights into the basics of cryptography.
The first part covered public-key cryptography: the idea is to enable encrypted communication between two unknown parties Alica and Bob: Alice and Bob agree on some common information that is made public. Then, both choose their (own) secret key that is only known to them, and then use the public information to derive a public key from their private key. In order to establish a common secret key, Alice sends her public key to Bob, who combines it with his own secret key. Bob also gives his public key to Alice, who can obtain the same secret as Bob did using her private key. The common secret is only known to Alice and Bob and can then be used for encryption.
This scheme can be implemented using primitive roots (which can be used to create a mathematical field). Binary sequences could be used as well, but they are easy to attack and therefore impracticable.
The last part was designed for "more advanced Dummies". Prof. Zumbrägel showed us modern (runtime) problems of Cryptography as well as past and current records (some of which he even helped establish).
All in all, it was a very interesting talk that provided a good opportunity to learn the very basics of cryptography.