作者abelian (abelian)
看板NetSecurity
标题Re: [讨论] 密码学?
时间Sat Nov 15 16:24:26 2008
: 除了最原始的凯萨编码(MAN → PDQ ABC → DEF)&凯撒方格
: 以及Base64
: 还有哪些常见的编码方式阿??
: ASCII也算是一种吗@@?
sorry, I can't type in Chinese
密码学 is cryptography.
编码 is coding theory.
The purpose and idea is different in many ways
cryptography is trying to hide the information.
coding theory is not to hide information, but to have a way to get back the
information when some noise is introduced.
If we just consider the purpose of ASCII, then ASCII is neither of those.
ASCII is just a mapping from human readable symbols to machine readable
symbols
the idea behind 密码学 is that some functionality, is easy in one way, but
hard to do in the other way..
for example, RSA depends on factoring 2 primes.
another idea is DLP (discrete log problem), ie, given a, b, and the relation
that a^x = b, how to find x
chen
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