Trusted Third Party (TTP)

Introduction:
Trusted Third Party (TTP) is an entity that facilitates interaction between two different parts, both of whom trust the third party and can rely on information given by the third party. This means that two parts setting up a connection can use the TTP to secure their own interaction.

Example:
Alice and Bob wish to use encryption to grant safe communication, without ever having meat Bob, Alice must obtain a key that can be used to encrypt the messages to Bob. In this case TTP (often called Trent) can be someone who has previously meet Bob or that can confirm that "this" key belongs to Bob, Alice can then use the key to send encrypted messages to Bob. In other words Alice can trust the key to belong to Bob if she trusts Trent. It is assumed that she has valid reasons to trust Trent and is able to identify Trent properly, and ensure that it isn’t someone impersonating Trent.

In use:
TTP is common to use in commercial transactions, cryptographic digital transactions and in cryptographic protocols, like certificate authority (CA).