11.16.2010

.NET Encryption - Part 1

In this series, I’ll target .NET encryption. These will be a series of articles to avoid extensive blog posts.
I want to make a kind of a personal bookmark for whenever I need to use it. Heck, that’s one of the reasons most of us keep technical blogs, right?
Encryption is one of those things we don’t tend to use on a daily basis, so it’s nice to have this kind of info stored somewhere to help our memory!

In this Part 1, let’s start by remembering a few concepts:

Symmetric encryption
In this method, a single key is used to encrypt and decrypt data, hence, both the sender and the receiver need to use the exact same key.
Pros:
  • Faster than asymmetric encryption
  • Consumes less computer resources
  • Simpler to implement
Cons:
  • The shared key must be exchanged between both parties, that itself poses a security risk. If the key exchange must not be compromised!

Asymmetric encryption
This method uses two keys: the private key and the public key. The public key is publicly available for everyone who wishes to send encrypted messages. These encrypted messages can only be decrypted by the private key. This provides a scenario where everyone can send encrypted messages, but only the receiver bearing the private key is able to decrypt the received message. 
Pros:
  • Safer, because there’s no need to exchange any secret key between the parties involved in the communication
Cons:
  • Slower than symmetric encryption
  • Bad performance for large sets of data
  • Requires a Key management system to handle all saved keys

Hashing
Safer, because Hashing isn’t encryption per-se, but it’s typically associated with it. Hashing is a mechanism that given an input data generates a hash value from which the origin data cannot be deduced. Typically a small change in the origin message can produce a completely different hash value. Hash values are typically used to validate that some data hasn’t been tampered with. Also when sensitive data (like a password) needs to be saved but its value is never to be read (only validated against), the hash can be saved instead of the data. 


That's all folks! In the next part(s) I'll cover the encryption algorithms available in .NET, how to choose among them, some real-life scenarios and source code examples.

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