cryptography... what's difference between 8bits / 16 bits / 32 bits/ 64 bits/128bits?
I have some question, is there anyone who can help me please?
what's difference between 8bits / 16 bits / 32 bits/ 64 bits/128bits encryption password?
How do you define each one?
And where do you use them?
Example: when i enter my password(which contain 8 characters) to enter my hotmail.com account, the password which i entered, is that 8bits? 16bits? 32bits? 64bits? or 128bit? and why??
8 characters = 8 bytes = 64bits??? so am i using 64bits encryption password???
sorry to be so newbie...
Generally speaking as the number of bits is increased, the strength of the phrase is increased against a cracking by brute force. In truth, it gets a lot more complex than that as passwords are not usually stored straight out, but hashed through algorithms to make them stronger and avoid having to transmit the real password. In theory the mapping is one to one, but this isn't always the case. As an example of what I mean if your password is "abc123" it may get hashed into "1234567890", which is then transmitted to the server which compares against the hashed value. This way, the server doesn't need to know your "real" password. The 'bits' comes into play in regards to the strength of the hashing and in terms of the character set used. If for example, you limit yourself to using the standard 127 ASCII characters you have a lot lower 'bit strength' in your password than if you used a full ISO character set because there are fewer combinations that can be made.
The above is a pretty crude explanation. Wikipedia has a good explanation of how this works. Here is a link: http://en.wikipedia.org/wiki/Password_strength
the difference from 8 bit to 128 bit
PRE-WW I to WW II
pre1914 to 1940
wasn't the enigma a 128bit cypher
The following quotes are from this book:
"Principles of Computer Security: Security+ and Beyond"
Wm. Artur Conklin, Gregory B. White, Chuck Cothren, Dwayne Williams, Roger L. Davis.
Chapter 5: Cryptography, pg. 80:
I hope I didn't violate the "fair use" rule of copyright law in my post... :scratch:
The Enigma cipher was a chained-transposition cipher with (almost-)simple incrementing fixed rotors. Other contemporary ciphers such as SIGABA increased security primarily by perturbing the rotor-positioning cycle. But none of these ciphers really had a sense of "bits."
We do now know that German computers such as Konrad Zeus' seminal machines were at least considered for cryptographic purposes, but there simply aren't enough known records left after all that bombing.
The key-length of a modern cipher is a rough measure of security against brute force attack, but only to the extent of the quality by which the algorithm in question actually uses the key. The "ideal" n-bit cipher would have exactly one key which produces the correct decryption and every other one produces an incorrect result that is "uselessly dissimilar to" the one and only right answer.
But remember... the theoretical strength of a cipher's key is really a too-abstract notion of its actual, pragmatic security in practice. Most cryptosystems are broken due to attacks on the keying system. The pseudo-random number generator, for instance, might not be so random after all. The key might be known to consist of "printable" characters. The owner of the key might decide that he'd rather live a few more years, and to do so in possession both of his arms (or, more cravenly, "$10 million dollars richer than before"), than to continue refusing to divulge the secret. And so on.
|All times are GMT -5. The time now is 12:38 PM.|