Encryption schemes [closed]

Question

1.In class we have learned about how to perform challenge-response authentication using public key digital signature. As mentioned, there is a similar scheme that uses public key encryption. could you help me design that scheme? in the scheme the responder still has to perform an operation only he/she can do.

2.Advances in technology allow both people who design algorithm and hackers to have computers that work faster than the old ones. Does this increase in computer speeds works to the advantage of algorithm developers , hackers or it makes no difference at all.

Answer 1

1

Not sure how, couldn't be asked.. Sorry :(

2

Yes. 5 years ago cracking a 512bit encrypted key took several years using the super computer available that time.. Now the same file can be decoded within weeks, using the almighty ARM, GPU and CPU combinations of supercomputers.

In order to avoid getting encryption cracked. never keep copies(avoid saving) of the file.. always generate it from protected source in computer memory using the most up to date encryption methods with massively randomly generated keys(using the same key all round it very bad).

So - It gives advantage to everybody.. but not always in the same concept.

Good example is the ever so recent SSL V1.0 scare, where man in the middle cookies offered a way to use sensitive data WITHOUT cracking. And in many cases encryption is flawed by human error or betrayal.