DES is a secret key crypto algorithm created to use 56-bit keys. 3-DES uses DES three times with one, two or three keys, effectively giving you a larger key size, while not changing the algorithm. DES works only with 56-bit keys. (What about 40-bit DES, you ask? It is 56-bit DES but the key is padded effectively giving you only 40 bits... really weak.) With crypto -- assuming the algorithm is a good algorithm -- we are concerned with the effectiveness of a "brute force attack" -- how long would it take for someone to guess the key. For comparison shopping, consider a really, really fast computer -- as yet non-existent as far as we know -- that could guess a 56-bit key in 3.5 hours. That same computer would take 2 million million million years to guess a 128-bit key, such as IDEA and AES use.
By submitting your email address, you agree to receive emails regarding relevant topic offers from TechTarget and its partners. You can withdraw your consent at any time. Contact TechTarget at 275 Grove Street, Newton, MA.
Foundations: Cryptography 101 Smith, Richard, Internet Cryptography, Addison-Wesley Pub Co; ISBN: 0201924803 Schneier, Bruce, Applied Cryptography: Protocols, Algorithms and Source Code in C, Second Edition, John Wiley & Sons; ISBN: 0471117099.
Dig Deeper on Disk Encryption and File Encryption
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.