Introduction to Cryptography

The field of cryptology

Cryptology — literally “the study of secrets” — is composed of cryptography (making codes) and cryptanalysis (breaking codes). However, many people use the term cryptography interchangeably with cryptology. 

Cryptographic algorithms underpin many of the digital technologies that we use today, and their security is essential to allowing the internet (and other systems) to work as intended. Understanding how they work and how they can be broken is essential to using them effectively and securely.

Classifying cryptosystems

Many different cryptographic algorithms exist and they can be classified in a few different ways. One of the fundamental classifications is encryption algorithms (which perform a reversible transformation on data) versus hash algorithms (which are a one-way transformation). Encryption and hash algorithms use many of the same mathematical concepts but have different objectives.

Within the space of encryption algorithms, there are a few different types of algorithms. Common classifications are symmetric versus asymmetric ciphers and — within the space of symmetric ciphers — block versus stream ciphers.

Symmetric vs. asymmetric ciphers

Symmetric and asymmetric encryption algorithms both have the same goal: to protect the confidentiality of data from anyone who doesn’t have a decryption key. However, they accomplish this in different ways.

Symmetric ciphers use the same secret key for encryption and decryption. In general, these algorithms are faster to run, making them better for bulk data encryption.

Asymmetric encryption algorithms use a private and public key that are related by a certain mathematical operation. The public key is used for encryption and the private key is used for decryption. This makes it possible to send an encrypted message without sharing a secret key first.

Block vs. stream ciphers

Symmetric encryption algorithms are further broken down into block and stream ciphers. These algorithms are differentiated by how they organize (Read more...)

*** This is a Security Bloggers Network syndicated blog from Infosec Resources authored by Howard Poston. Read the original post at: http://feedproxy.google.com/~r/infosecResources/~3/_Hff_Cf3Bz4/