Encryption is the science or system of encoding or enciphering data to secure it. The word encryption comes from the prefix en- meaning “to cause to be in” and the root crypt which was abstracted from words such as cryptic and cryptography so that encrypt could be similar to the existing word encode. The opposite of encrypt is decrypt, just as the opposite of encode is decode. An encryption system is a standardized approach to encryption and decryption of messages.
Using an encryption system promotes privacy and security. Even if someone got hold of the ciphertext, it would not be easy to read. Moreover, encrypting data helps to make sure that the data is not altered during transmission. In addition, encryption systems are set up for authentication, meaning that the identity of the sender of the message and his or her right to engage in certain types of activity — such as initiating a credit card purchase using a particular name and account — is verified by the system. Finally, the encryption system offers a guarantee that the purported sender undeniably was responsible for the origination of the message.
There are several important types of encryption system used in network cryptography. On the one hand, there is the Symmetric-Key Encryption system, which is also known as Secret Key Cryptography (SKC). This system uses only one key to both encrypt and decrypt data. The original Symmetric-Key Encryption system used the Data Encryption Standard DES), which has since been replaced by the Advanced Encryption Standard (AES).
The other primary type of encryption system is the Asymmetric or Public-Key Encryption system, which is also known as Public Key Cryptography (PKC). The Public Key method uses a pair of keys, one that encrypts the data and a second to decrypt it. This system uses digital certificates issued by a Certification Authority (CA), which is a trusted third party, for verification.
The Public-Key Encryption system is implemented both through Secure Socket Layers (SSL) and through Transport Layer Security (TLS). The use of TLS is what leads to a web page address of “https” rather than simply “http” as a sign that the digital certificate for the page has been verified and that data processed through the page will be encrypted. Browsers that have good security will provide a variety of warnings to users if a digital certificate ails the validation check.