[fitsbits] Hash Functions (MD5 is very obsolete)

[Rob Seaman]

Thierry Forveille wrote:

> Is anyone on the list aware of uses of the MD5 checksum in FITS  
> beyond protection against accidental bitflips from bad hardware?

Good question!

If the goal is to protect against data accidents (whatever the cause),  
the FITS checksum should be considered as a strong contender instead  
of any secure hash.

That said, MD5 is used by default for many astronomical data transport  
and archive chores.  As the broader computing communities continue to  
transition to SHA-2, support for MD5-based utilities will narrow.   
Remediating this is certainly not a top priority, however, which is  
why I worded it as a "reminder" :-)

When implementing new systems, there are few good arguments for  
choosing MD5.

Rob