Symmetric Cryptography
Symmetric algorithms do some things really well and other things not so well. Modern symmetric algorithms are great at all of the following:
■ Preserving confidentiality
■ Increasing speed
■ Ensuring simplicity (relatively speaking, of course)
■ Providing authenticity
.ymmetric algorithms have their drawbacks in these areas:
■ Key management issues
■ Lack of nonrepudiation features
First let’s focus on the defining characteristic of symmetric encryption algorithms: the key. All algorithms that fit into the symmetric variety use a single key to both encrypt and decrypt (hence the name symmetric). This is an easy concept to grasp if you think of a key used to lock a gym locker as the same key used to unlock it. A symmetric algorithm works the exactly the same way: the key used to encrypt is the same one used to decrypt.
