Overview of encryption

1. Encryption. Symmetric and asymmetric.

Encryption is a technology used to protect information by transforming it into something unreadable (without particular additional, often secret, information). Encryption uses different algorithms and protocols developed in the branch of mathematics called cryptography.

Encryption is used in

• secure communications (spies and diplomats uses it since diplomacy and espionage were invented),
• protecting and secure sharing of confidential information,
• identifying who is the source of secure document (using so called digital signatures)
• authentication.

Combination of encryption methods can make possible implementation of complicated services, for instance secure electronic mail, certification, electronic commerce, key recovery, and secure computer access.
Encryption process uses the encryption algorithm and encryption key to transform data (called cleat text or plain text) into encrypted data (called cipher text).

Figure 1

Decryption process uses the decryption algorithm (corresponding to encryption algorithm) and decryption key to transform cipher text into cleat text.

Figure 3

Decryption key could be different from encryption key. Encryption algorithm called symmetric if the encryption key is the same as the decryption key. This key is usually called secret key. Otherwise, encryption algorithm called asymmetric. Set of encryption key and decryption key in this case usually called key pair.