Cryptography not only protects data from theft or alteration, but can also be used for user authentication.
Cryptography cover these essential area:
Authentication - Sender and Receiver can confirm each.
Integrity - Information cannot be altered.
Confidentiality - Information cannot understand by anyone.
Types of Cryptography:
In symmetric-key cryptography Used to both the sender and receiver share a single key. The sender use this key to encrypt plaintext and send the cipher text to the receiver. On the other side the receiver applies the same key to decrypt the message and recover the plain text. It is also called Secret-key cryptography.
In public-key cryptography used to two keys (public and private key) .The public key is used for encrypt data and the private key is used for decrypt data. It is also called asymmetric-key cryptography. One key is the public key that anyone can access and the other key is the private key that only owner can access it.
In hash functions not used any key. Hash functions is used to many operating system to encrypt passwords.
MD5 - d41d8cd9 8f00b204 e9800998 ecf8427e