Sha1/2 encryption on Unity 4.2?

Is there any way to encrypt a password to send it over the network in Unity 4.2? In 3.4 I found System.Security.Cryptography.MD5CryptoServiceProvider(); but I, even if it works, I can’t find it on 4.2 docs!! Also Im looking for a better algorithm like Sha1/2

You can use MD5 as well as SHA1/2 in Unity 4.2. All are included in Unity Mono Compatibility page.

Microsoft .NET managed cryptography providers rely on native providers installed in Windows. I don’t know how Mono implementation works, but I guess it works the same way. So my advice is to check if your target platform supports the chosen algorithm.

Unity for itself does not have cryptography library.
It uses and translate the C# library.

I´m not sure which platforms are supported, but I suggest you to look the msdna documentation for more info about the Security package. (I guess supported by all except flash, but not sure about it)