Understanding Computer Security: Encryption and Key Concepts
Understanding Computer Security
1. Securing Your Computer System
Computer security is the practice of protecting an entire computer system, including users, hardware, software, and files.
2. Understanding Encryption
Encryption is a method used to render a message unintelligible to users who do not possess the key. It ensures a secure means of communication for a specific group.
3. Manual Encryption Techniques
Here are three types of manual encryption:
- The Scytale (Bat Lycurgus): The sender writes the message along a staff, then unwinds the strip. This converts the message into a meaningless sequence of letters. The recipient wraps the strip around a staff of equal diameter to read the message.
- Polybius Square: Each letter is represented by a combination of two numbers, corresponding to its position in a grid.
- Caesar Cipher: Each letter of the original message is replaced by the letter three positions down the alphabet (A becomes D, B becomes E, and so on, wrapping around from Z to A).
4. Cryptographic Algorithms Explained
Cryptographic algorithms are mathematical transformations that convert a clear message into an encrypted message and vice versa.
5. Weak vs. Strong Encryption
- Weak Encryption: A simple method of hiding information, easily deciphered by those with basic knowledge. Example: A simple cryptogram puzzle.
- Strong Encryption: High complexity designed to protect information even against intense scrutiny by supercomputers. Example: PGP (Pretty Good Privacy).
6. Forms of Encryption
Three forms of encryption include:
- Hand-made: Encryption performed manually using a predetermined process.
- Machine-based: Encryption using a predetermined table in conjunction with a machine. The operator uses the table and machine to send an encrypted message.
- Network-based: Encryption using algorithms within a network.
7. Steganography: Hiding Messages in Plain Sight
Steganography is communication by concealing secret messages within other, non-secret data. Examples include watermarks and digital fingerprinting.
8. Key Security Concepts
The following concepts are crucial for information security:
- Availability: Ensuring information is accessible when needed.
- Integrity: Ensuring the message content remains unaltered.
- Access Control: Ensuring only authorized individuals can access the message content.
- Non-Repudiation: Preventing the sender or receiver from denying the sending or receiving of a message.
- Privacy (Confidentiality): Preventing unauthorized access to message content, ensuring only the intended recipient can read it.
9. Cryptographic Keys
In computer cryptography, a “key” is the code used to decrypt an encrypted message. Keys can be public or private.
10. Symmetric vs. Asymmetric Encryption
- Symmetric Algorithms: Require that the key is kept secret and known only to the communicating parties.
- Asymmetric Algorithms: Allow the encryption key to be made public, making it available through a public channel.