Encryption is process by which one makes a digital document unreadable to anyone who does not have the key that has been used to Encrypt. Decryption is the proper way to reverse the process of Encryption to make it human readable. Previously we wrote about How to Encrypt Decrypt any file or folder from right click context menu in Windows 7.
Why we need to do Encryption
Although encryption can work fine for a secret document, other cryptographic techniques are also needed to communicate securely. To check the integrity or the authenticity of a document, using respectively a Message Authentication Code (MAC) or a digital signature we also use Encryption. The security of an encryption system must be based on the secret encryption key, not that of the algorithm. Kerckhoffs’s principle assumes that the enemy (or the person who wants to know the encrypted message illegally) knows the algorithm used.
Two main types of encryption methods are :
- Symmetrical : When it uses the same key to encrypt and decrypt.
- Asymmetrical : When using different pair of keys – a public key used for encryption and a private key for decrypting.
The best known methods are OF, Triple DES and AES for symmetric cryptography and RSA for asymmetric encryption. The use of symmetric or asymmetric depends on the situation. Asymmetric cryptography / Encryption has two major advantages: it eliminates the problem of secure transmission of the key and allows the electronic signature. It does not replace the symmetric systems because its computation time is significantly longer.
More on Encryption and Decryption
Encoding and Encryption are not the same things. The essential difference between Encryption and Encoding lies in the desire to protect information and prevent third parties from accessing data in the case of encryption. Encryption is to transform coding of information (data) to a set of words. Every word is made up of symbols. Encoding is an compression, it transforms the data to a set of words adequate to reduce the size but there is no desire to conceal (although this is done implicitly by making it harder to access the content) the data.