howto do a hash

[Werner Koch]

On Fri,  2 Jan 2009 11:36, sergi at calcurco.cat said:

> err = gcry_md_open(&hd,algo,GCRY_MD_FLAG_SECURE);
> err = gcry_md_enable(hd,algo);

The gcry_md_enable call is superfluous because you enabled algorithm
ALGO already with gcry_md_open.

> Then the buffer can be a 'byte array', and after the values concatenation, the 

I don't understand why you insist on a byte array; you may pass any
memory block to gcry_md_write.  Given that you know the hash algorithm
in advance and that there is just one contiguous memory range to hash, I
suggest to use gcry_md_hash_buffer instead.  This has the advantage that
it can be highly optimized on some CPUs (modern VIA CPUs ferature a
SHA-1 and a SHA-256 implementation which work on an entire buffer and
return the finalized hash).


Shalom-Salam,

   Werner

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