Encryption Hierarchy: - A hierarchical encryption is key management infrastructure. Each layer encrypts the layer below it by using a combination of certificates, asymmetric keys, and symmetric keys. Asymmetric keys and symmetric keys can be stored outside of SQL Server in an Extensible Key Management (EKM) module. The following illustration shows that each layer of the encryption hierarchy encrypts the layer beneath it, and displays the most en configurations. The access to the start of the hierarchy is usually protected by a password.

Symmetric encryption policy: - There are several ways to include hidden content in a message. In the beginning of cryptology, using invisible ink was a common method. That style of actually hiding is still in use today and called steganography. However, the term encryption today usually refers to the use of an algorithm that is transforming a readable message into an unreadable …show more content…
To decrypt that unreadable message you need to know two things. The algorithm used to scramble the message and the key. While there are algorithms that do not require a key, they are not considered secure anymore and their use should be avoided. In fact, any cryptographic algorithm that requires keeping the algorithm itself secret is considered weak and should not be used. The best way to identify a strong cryptographic algorithm is to take a published algorithm and look at how many cryptologists have tried to break it unsuccessfully. If the algorithm itself is known, there needs to be another secret ingredient - the key. The strength of a published encryption algorithm lies entirely in the key. Symmetric key encryption uses the same key for the encryption step and the decryption step. A (symmetric) key is usually a sequence of 128 to 256 bits.