# Who created cryptography

## Security

Today it is only possible to communicate securely electronically with the help of cryptography. Read how the term is defined, how it differs from encryption and which methods are used.

### Cryptography - Definition

Cryptography (literally translated: secret writing) is the science of keeping information secret. With the help of an algorithm, this information or data is converted into a form that cannot be read or understood by unauthorized persons. Cryptographic systems also require a way for the recipient to make the encrypted message readable again.

### Cryptography vs. Encryption

Encryption is the process that occurs when information is converted from its original form into a secret form. Encryption is an important part of cryptography, but it does not cover all aspects of science by far. The counterpart to encryption is decryption.

An important aspect of encryption is that, as a rule, both an algorithm and a key are used in the process. A key (usually a combination of numbers) represents additional information that specifies how the algorithm encrypts the original text. Even if the encryption method is known: Without the key, decryption is almost impossible.

### Cryptography - history

The origins of cryptography go back to the Caesar era: the Roman general used his own encryption system for confidential correspondence. The way it works is relatively simple, but it is well suited to illustrate the cryptographic interaction between key and algorithm. The Ceasar encryption works with the substitution of letters. The algorithm therefore provides for each letter in the text to be exchanged for another, later, in the alphabet. The key, on the other hand, provides information about which letter it is exactly - namely the one that follows in third place (for example, "A" becomes "D").

This example shows that simple encryption methods can also be used to send confidential messages. In addition, it becomes clear that a system consisting of passphrases would be impractical in this context: For encryption and decryption, both the sender and the recipient would have to have a collection of all passphrases - new ones cannot be added. With Caesar encryption, on the other hand, any content can be encrypted - provided that the algorithm and key are known to the communication participants. This type of substitution encryption has been further developed over the centuries - particularly through mathematics. Still, all encryption systems of the pre-computer era are pretty trivial from today's perspective.

With the emergence of the first computers, there were also significant advances in cryptography. During the Second World War, the Enigma code and its decryption by Alan Turing laid the basis for modern computer systems. The complexity of cryptography has increased incessantly since the advent of computers - but remained a field for secret services and the military for decades.

That changed in the 1960s with the emergence of the first computer networks. This new type of networked communication was revolutionary - but because of its security gaps it also ensured that civil users also recognized the need to encrypt communication content. IBM pioneered cryptography in the late 1960s with the Lucifer encryption method (which later became the first Data Encryption Standard). With the increasing importance of the Internet, the demand for new and better encryption methods also increased.

### Cryptography Uses

Specifically, cryptography is used, for example, to securely transmit confidential information (for example on the activity of secret services or financial information) electronically. In general, however, cryptography also helps to achieve higher cybersecurity goals:

• Keep data confidential

• Verify the identity of senders and recipients

• Secure data integrity and prevent manipulation

• Make sure that the message really came from the recipient

### Cryptography Methods

A large number of cryptographic algorithms are currently in use. In general, these can be classified into three different categories:

• Secret key cryptography is widely used to keep information and data confidential. Caesar encryption would be an example of this. As already described, both the sender and the recipient must know the algorithm and key. However, the key must be treated confidentially between these two parties. Therefore the key cannot be "sent" with the message, otherwise all efforts would be for the cat. This method is useful, for example, to secure local hard drives that are accessed by the same user - in this case the secret key does not have to be shared. This cryptographic method is also suitable for sending confidential messages over the Internet - but only in combination with the following method.

• In the case of the Public key cryptography The sender and recipient each have two different keys: a public key, which is responsible for encrypting the information, and a private key for decryption. The mathematical calculations that are necessary to encrypt messages with one key and decrypt them with another is far less intuitive than, for example, Caesar encryption. Interested parties will find an extensive deep dive on the topic here. The basic principle that makes this method possible: The keys are mathematically related to each other, so that the public key can easily be calculated from the private key, but not the other way around. Public keys are also part of a public key infrastructure that enables each of the keys to be assigned to a specific person or organization. Messages that are encrypted with a public key therefore authenticate the identity of the sender.

• Hash functions In contrast to secret and public key cryptography, they are "one-way streets" algorithms: Once encrypted, there is no way to reconstruct the original form of a message from a hash. This may sound relatively pointless at first, but it has the advantage that no message can have the same hash value as another. This ensures data integrity. Hash functions are also used in connection with password security: Saving passwords in plain text format is an absolute security no-go, which has already led to numerous data leaks. If, on the other hand, passwords are stored in hash format, it is much more difficult for criminal hackers, for example, to use this information for further compromises.

### Cryptography Examples

In order to implement the cryptographic methods just described, there are a number of techniques that are generally very complex. Here are some additional links if you want to delve deeper into the subject of cryptography:

Secret key encryption:

Public key encryption:

Hash functions:

This article is based on an article from our US sister publication CSO Online.