Sha512 Implementation

[satvikc]

How should I capture length of message in this case as it will be 2^128. Should I use Integer or 2 Word64?

[satvikc]

There is also a problem in Hash typeclass in which you assumed message size can not be greater that sizeOf Word64

[satvikc]

I also need 128bit Big endian Word while encoding the padding.

[piyush-kurur]

I had thought about this. No machines currently have 128-bit native integers. To accomodate sha512 we would have to
use Integer for all hashes which will unnecessarily slow down things. If you think about it. It is going to be a problem if and only if the message size goes beyond 2^64 bits which actually is quite large. about 1024 petabytes.
For network applications this limit will almost never be exceed (Think of using hmac-sha512 to compute the mac of ssh packets). What we can do is we can document this as a limitation of the library and when Word128 arrives on GHC we can implement it.

You can implement the 128 but BE padding by actually storing 2 64 bit BE numbers, the first being just 0.

[satvikc]

Ok.. I have done sha 224,256,512 and doing sha 384. what others we have to do?