With full hard disk encryption, every sector of the hard disk is encrypted. Some access control products provide this feature. The following factors vary from one product to another:
1. Reduced performance
The more powerful the encryption algorithm, the poorer the performance of the computer. It is customary to choose a less powerful algorithm for full hard disk encryption so that performance does not suffer too much. For example, a test showed that full hard disk encryption using DES increased Windows startup time by 600-700%.
2. Encryption power
A compromise always has to be reached to ensure encryption does not unacceptably reduce computer performance. The most widely used algorithms - simple XOR, blowfish or proprietary algorithms (developed by individual companies) - maintain the best possible performance.
3. Handling 16 and 32 bit disk access
Many products have difficulties if 32 bit disk access is used in Windows. You should bear this in mind if individual applications require 32 bit disk access. There is a simple test that those uninitiated in the world of cryptography can use to determine the power of an encryption algorithm. Create a file containing nothing but the same character. It is a sign of weakness if the encrypted result also contains only a series of identical characters.
Poor encryption algorithm :
Unencrypted data : AAAAAAAAAAAAAAAAAAAAA
Encrypted data : BBBBBBBBBBBBBBBBBBBBB
Good encryption algorithm :
Unencrypted data : AAAAAAAAAAAAAAAAAA
Encrypted data : #sah&%8jJnOlp)D#g1Hu/