People have always encrypted important messages when they were transported over long distances. In times of digitalisation, the topic is more important than ever, because we transmit sensitive data every day.
The word “cryptography” comes from the Greek and means secret writing. Today, this science is mainly concerned with the encryption of data in order to protect it from being accessed by third parties.
Cryptography is subject to constant further development. For example, Julius Caesar already used a simple form of encryption in which he replaced each letter with the third closest letter in the alphabet. Only those who knew that they had to shift the message back by three letters could decode the message.
During the Second World War, mechanical and electromechanical key machines such as the ENIGMA were already in use. They allowed messages to be encrypted so effectively that the key could only be cracked by the British after several years.
Data encryption is still a relevant topic today. Every day, we transmit data that should not fall into the wrong hands: from credit card information to login data to WhatsApp messages. But how exactly does encryption work?
The most important methods of encryption today are symmetric and asymmetric cryptography.
In symmetric encryption, the sender and recipient of the message use the same key. Of course, both must know it. To ensure sufficient protection, it must be transmitted unencrypted and separate from the message, i.e. at best in person. Things get really complicated when the number of participants increases, but not everyone is supposed to be able to read all the messages. Then several different keys must be used, and they must not be mixed up.
Asymmetric cryptography, on the other hand, works with a mathematically linked key pair consisting of a public and a private key. Every user can send messages with the public key, but decryption is only possible with the private key. Thus, only one key pair is needed for each participant.
Cryptography is therefore always used when only the person for whom a message is intended should be able to read it (confidentiality / access protection). In addition, it also ensures the integrity of a message, because the recipient must be able to trust that the message has not been changed after it was created (change protection). Authenticity can also be checked and thus the author or sender can be clearly identified (forgery protection). And last but not least, cryptography also ensures bindingness by documenting the originator of the data or message (non-repudiation).
This makes it possible, for example, to create digital signatures or to authenticate oneself in an interactive communication.
When it comes to data protection and IT security, cryptography is therefore a top issue.