SecretSoftware wrote:
But you can produce 2 different documents with the same SHA-1 hash. So someone can fake a digital signature of a message, and cause problems.
I am going to use combinations of SHA-512 and WhirlPool in my applications. A combination is always good. The WirlPool hash of the SHA-512 hash.
Again: PLEASE read some books on the topic!
1) SHA256 is or even SHA512 is not broken. Of course (as you wrote) there will be a point in time where it can be brute-force calculated. But with current knowledge that will be billions of billions of years in the future for SHA256 and for SHA512 that will be even a LOT later. As already posted just use SHA256 or if you are somewhat paranoic SHA512.
2) Combinations of crypto algos it about the WORST thing you can do. You ENTIRELY loose predictability and you may get a result that is actually LESS secure than each of the individual source algorithms alone. And even in a good case the effect would be really small (like going from a SHA512 to imaginary SHA513).
