cc DSA是基于整数有限域离散对数难题的，DSA的一个重要特点是两个素数公开，这样，当使用别人的p和q时，即使不知道私钥，你也能确认它们是否是随机产生的，还是作了手脚。RSA算法却做不到。
RSA算法在网络容易实现密钥管理,便进行数字签名,算法复杂,加/解速度慢,采用非对称加密
DSA = Digital Signature Algorithm. based on discrete logarithms computation.
DES = Digital Encryption Standard. Obsolete standard.
What is DCE?
DSA 用于签名，而 RSA 可用于签名和加密。
DSA is faster in *signing*, but slower in *verifying*.
A DSA key of the same strength as RSA (1024 bits) generates a smaller signature.
An RSA 512 bit key has been cracked, but only a 280 DSA key.
It doesn’t matter because with Ssh only authentication is done using RSA or DSA algorithm, and then the “rest” is encoded using a (uh, was it block?) cipher like IDEA, DES, Blowfish, etc, etc after the authentication is done.
While SSH2 can use either DSA or RSA keys, SSH1 cannot. Ssh2 will also not use patented cypers like IDEA.
Filed under: System — Tags: cryptography — Commen
RSA的安全性一直未能得到理论上的证明。 RSA的安全性依赖于大数分解。公钥和私钥都是两个大素数（ 大于 100个十进制位）的函数。据猜测，从一个密钥和密文推断出明文的难度等同于分解两个大素数的积。
