Cryptography is the science of cryptographic algorithms (known as Cipher) that implements the following functionalities:
Cryptographic algorithms transforms:
- and vice versa (decryption (backward))
Hashing (Data Integrity and Signature)
- without secret
- with secret (known as signature)
Anonymity Security : Kerckhoffs Principle
In designing security systems, it is wise to assume that the details of the cryptographic algorithm are already available to the attacker. This is known as:
- Kerckhoffs' principle only secrecy of the key provides security,
- or, reformulated as Shannon's maxim, the enemy knows the system.
An attacker who obtains the secret (key) can :
- and issue signatures.
Alice and Bob are fictional characters commonly used as placeholder names in cryptology