Why are mysql password hashes internally saved with a star (asterisk)?
Ok, found about this in the documentation itself.

This was a change introduced in mysql 4.1 so that the earlier password lengths of 16 characters and newer password lengths of 40 characters could be simultaneously supported. The Password column was made 41 bytes (chars) long, and the newer passwords would begin with a mandatory * to identify them.

From the documentation:


  Password hashes in the 4.1 format always begin with a “*” character, whereas passwords in the pre-4.1 format never do.