1. Encryption

2. What is encryption? Encryption is conversion of original data to another data that can be converted back to original data by authorized persons. For example: – Cell phone call – SSL web site protocol – Answer sharing during exam

3. Basic types of encryptions Shared key (Symmetric key) encryption – Same key for encryption and decryption. For example: Zip or Rar encrypted archive Encrypted Word, Excel, Power Point document Sometimes national security agents use little-known languages Public key encryption – Two keys: one for encryption and another for decryption. For. Ex.: SSL secured web site protocol (partically) Certificate sing E-GOV key

4. Shared key Encryption and decryption processes use same key

5. Simple shared key

7. Public key Public key consists of two keys: – Public key (known by everyone) – Private key (known only by authorized person) Used in two main directions: – First: Anyone can send message encrypted using public key but only authorized person can decrypt it – Second: Only authorized person can encrypt message by private key, everyone can decrypt it by public key (everybody sure that message from authorized person)

8. Public key One private key One public key

9. Public key One private key One public key