Join Lisa Bock for an in-depth discussion in this video Exploring encryption and cryptographic techniques, part of Foundations of IT Security: Core Concepts.
- A Cipher is a code that uses a secret key in order to conceal data. Taking a block of plaintext and converting it into ciphertext is called encryption. Taking a block of ciphertext and converting it into plaintext is called decryption. Encrypting data has been used for centuries. Many times, during war efforts. For example, a scytale is a baton-like tool with a strip of parchment or leather wrapped around it concealing a message.
The baton had angles, so as the parchment or leather was wrapped around it, it would allow the user to see the message. Unwrapped, the message would be meaningless. For example, if we use the scytale to encode the following message: "Julius Caesar used a simple alphabetic cipher," using a baton with five angles, this would translate to the following when wrapped around the scytale. When unwrapping, you see that it is just a series of letters, and it would be meaningless to anyone who saw it who didn't have the scytale.
Modern Cryptography uses encyrption algorithms and digital keys to encrypt and decrypt data. The two main types of encryption algorithms are Symmetric and Aymmetric. Symmetric or conventional enctryption uses a single shared key to encrypt data and includes algorithms such as DES, 3DES, and AES to provide fast, efficient encryption. Symmetric encryption is used for confidential, online communications such as an SSL transaction or, Secure Multi-Purpose Internet Mail Extensions, or S/MIME to encrypt messages for confidential email.
Asymmetric or public key encryption uses two keys: a public key and a private key, which are mathematically related and includes examples such as RSA or PGP. Uses for asymmetric encryption include key exchange, confidentiality using encryption, authentication, and creating digital signatures. In addition to encryption, cryptographic techniques such as hash functions are used to protect data. Unlike encryption, a hash function is one-way.
It takes a variable length input and produces a fixed length output. Encryption and cryptographic techniques can sure us of the following: confidentiality, which protects data against unauthorized disclosure. We use encryption. Integrity ensures data has not been changed, destroyed or lost in an unauthorized, or accidental manner. We use a hash function. Accountability. Positively identifying an entity in a system, such as signing an electronic contract.
We use a digital signature. And, Authentication. Confirm the identity of a system entity. Here we use a Method Authentication Code.
Note: This course maps to a number of the exam topics on the Microsoft Technology Associate (MTA) Security Fundamentals 98-367 certification exam and is recommended test prep viewing.
- Evaluating risks, threats, and vulnerabilities
- Minimizing the attack surface
- Avoiding worms and viruses
- Protecting your system from spyware
- Making web browsers more secure
- Securing wireless transmissions
- Encrypting files, folders, and drives
- Using virtual private networks