void silc_hash_init(SilcHash hash);

    Sometimes calling the silc_hash_make might not be the most optimal
    case of computing digests.  If you have a lot of different data
    that you need to put together for computing a digest you may either
    put them into a buffer and compute the digest from the buffer by
    calling the silc_hash_make, or you can use the silc_hash_init,
    silc_hash_update and silc_hash_final to do the digest.  This function
    prepares the allocated hash function context for this kind of digest 
    computation.  To add the data to be used in the digest computation
    call the silc_hash_update function.