**Hybrid system** is a __basic key transport protocol__ that incorporates both **Asymmetric** and **Symmetric** **Algorithms**. In another word, this system uses a combination of both (**public-key**) and (**private-key**). This Hybrid system provides the following:

: for__Key Exchange__**Symmetric schemes**; and digital signatures are performed with (*slow*)**Asymmetric algorithms**.of data is done using (__Encryption__*fast*)**Symmetric Ciphers**such as,**Block Ciphers**or**Stream Ciphers**.

The following example shows both **Symmetric** and **Asymmetric Cryptography** to achieve **Hybrid protocol** (using the AES operation to exchange data).

**Description: **The figure above shows the process of Hybrid Protocol that provides both Symmetric and Asymmetric Algorithm to eventually exchange data securely.

- Any party can start this communication, but in this case Bob started by generating two different keys (
**public-key**and**private-key**). **Bob**will send his**public-key**to**Alice**.**Alice**generates a random number and encrypt her number using**Bob’s public-key**; and send the result to**Bob**; as an encrypted message.**Note:**if the message get corrupted, it means nothing because it is only an encrypted number (useful for**Alice**and**Bob**, but useless for anyone else).**Bob**will use his**private-key**to decrypt the message to know**Alice’s key**.**Asymmetric algorithm**has been achieved by exchanging the key between**Alice**and**Bob**.- Now,
**Alice**can encrypt any message and send it to**Bob**security, where**Bob**can only decrypt this message. **Symmetric****algorithm**has been achieved by exchanging the data between**Alice**and**Bob**.

**Note:** the **public-key** can be public to anyone; and we do not care if any third party, **Oscar** for example, got a copy of it. However, the **private-key **must be kept secret and should be available to no one by the generator himself/herself (in our case **Bob**).

The attached link shows an animation video about the hybrid-protocol process and how it works step-by-step.