Opinions on RIPEMD vs SHA?

[Robert J. Hansen]

> I'm considering making my default hash RIPEMD160: does anyone have any
> opinions on how this compares to SHA-2 algorithms in terms of both
> security and availability?

The new SHAs have the benefit of about a dozen years of cryptanalytic  
research behind them.  RIPEMD160 is very similar to SHA-1, and the  
recent attacks against SHA-1 are likely applicable to RIPEMD160.   
Those same attacks do not apply against the newer SHAs.

> I have no problem looking past this bit of romanticism.

"Romanticism" is exactly the right word to use.

> I'm especially curious if RIPEMD160 is commonly available
> in popular PGP clients.

Yes.  It's been in PGP since 6.5.8, and in GnuPG since 1.0.  (Probably  
since long before 1.0, but since 1.0 was the first official release,  
that's where I trace things back to.)