Question

Difference between authenticity and confidentiality

Answer 1

Confidentiality: Confidentiality is used to make sure that nobody in between site A and B is able to read what data or information is sent between the to sites. To achieve this encryption algorithms are used. There are two kinds of encryption algorithms, symmetric and also asymmetric ones. Symmetric algorithms allow encryption and decryption with the same key. With asymmetric algorithms you have to kinds of keys: a public one and also a private one. The public key is often available to the public while the private key is just available for "yourself" (if the mentioned keypair is yours). Everything that you encrypt with the public key can only be decrypted with the private one and vice versa. When it comes to confidentiality you often just use symmetric algorithms like DES, 3DES (both outdated) or AES. Asymmetric encryption is used to transfer a symmetric key and also to make sure that the other site is really who it seems to be (when it comes to SSL/TLS).

Authenticity: And this last sentence of the confidentiality part leads directly to the authenticity part. Authenticity is used to make sure that you really communicate with the partner you want to. To achieve these different kinds of techniques can be used, e.g. Pre-shared keys that are configured on both sites, Elliptic Curves or RSA as public/private key algorithms.