How Cryptography Works
Depending on the purpose of the correspondence and availability of hardware, there are several cryptographic techniques that can be employed to secure the transaction of data. But regardless of the approach used, all forms of cryptography and their methods of operation have a similar structure.
Cryptography makes use of a code known as an encryption algorithm, which takes information (usually in the form of plain text) as its input. Depending on the complexity of the encryption sought, the plain text is converted to what is known as cyphertext (or substrate) and then transmitted to its intended recipient. This means that during the transmission process, even if the data is intercepted by an unauthorized third party, it will be virtually useless.
Once the message reaches its intended recipient, it is run through a code known as a decryption algorithm so that it can be made legible again. A lot of time this happens seamlessly without input from the end user.
The Primary Types of Cryptography
The type of cryptography being implemented can often be identified by its encryption key. A symmetric key makes use of related (an in some cases, identical) parameters to encrypt or decrypt data. Also known as secret key encryption, this approach is much like physical scenarios in which the key used to lock a door is the same one used to unlock it.
This approach obviously has some limitations. It is relatively easy to change these types of keys, and, if anyone can fashion one like it, they, too will be able to “unlock the door” and gain access to the resources behind it. Several algorithms fall under the symmetric key category, including AES (-128, -192, -256), RC4, RC5 and RC6.
An asymmetric key, on the other hand, is what is known as public key encryption. Unlike its symmetric counterpart, an asymmetric key uses a set of parameters for encryption, and another set of parameters for decryption. The public key is made available to each participant in the communication process, while the private key is used to decipher the message(s) sent.
In asymmetric cryptography, each correspondent must request access to a certain resource. The sender would then lock it (or encrypt it) and transmit it over the Internet. The recipient must then use their unique private key to decrypt the message and gain access.
Contrary to the “key and door” scenario previously illustrated, asymmetric cryptography is advantageous since the secret key is unique to each recipient and store on their personal device. Unless they share it, this mode of encryption is not easily broken.
Modern Cryptographic Use Cases
Cryptography has many use cases, many of which we remain oblivious to. Authentication methods which require the input of a username and/or password are basic forms of cryptography, while advanced patterns are used to strengthen a user’s privacy online. Furthermore, cryptography is needed to preserve the integrity of data as it is transported between databases and applications.
Most, however, are familiar with the use of cryptography in monetary frameworks. For example, malicious programs like ransomware use cryptography to hold data ransom in exchange for money. The payment is usually in the form of Bitcoin or some other cryptocurrency due to its strong encryption techniques and decentralized control.