urbit/jets/e/hmac.c
2018-07-13 02:03:08 +02:00

89 lines
2.6 KiB
C

/* j/5/hmac.c
**
*/
#include "all.h"
/* functions
*/
u3_noun
u3qe_hmac(u3_noun haj,
u3_atom boq,
u3_atom out,
u3_atom wik,
u3_atom key,
u3_atom wid,
u3_atom dat)
{
c3_assert(_(u3a_is_cat(boq)) && _(u3a_is_cat(wik)) && _(u3a_is_cat(wid)));
// ensure key and message fit signaled lengths
key = u3qc_end(3, wik, key);
dat = u3qc_end(3, wid, dat);
// keys longer than block size are shortened by hashing
if (wik > boq) {
key = u3n_slam_on(u3k(haj), u3nc(wik, key));
wik = out;
}
// keys shorter than block size are right-padded
if (wik < boq) {
key = u3kc_lsh(3, (boq - wik), key);
}
// pad key, inner and outer
c3_y trail = (boq % 4);
c3_y padwords = (boq / 4) + (trail == 0 ? 0 : 1);
c3_w innpad[padwords], outpad[padwords];
memset(innpad, 0x36, padwords * 4);
memset(outpad, 0x5c, padwords * 4);
if (trail > 0) {
innpad[padwords-1] = 0x36363636 >> (8 * (4 - trail));
outpad[padwords-1] = 0x5c5c5c5c >> (8 * (4 - trail));
}
u3_atom innkey = u3kc_mix(u3k(key), u3i_words(padwords, innpad));
u3_atom outkey = u3kc_mix( key , u3i_words(padwords, outpad));
// append inner padding to message, then hash
u3_atom innmsg = u3ka_add(u3kc_lsh(3, wid, innkey), u3k(dat));
u3_atom innhaj = u3n_slam_on(u3k(haj), u3nc((wid + boq), innmsg));
// prepend outer padding to result, hash again
u3_atom outmsg = u3ka_add(u3kc_lsh(3, out, outkey), innhaj);
u3_atom outhaj = u3n_slam_on(u3k(haj), u3nc((out + boq), outmsg));
fprintf(stderr, "\naaaaaa\n");
return outhaj;
}
u3_noun
u3we_hmac(u3_noun cor)
{
u3_noun haj, boq, out, wik, key, wid, dat;
// sample is [[haj boq out] [wik key] [wid dat]]
if ( (c3n == u3r_mean(cor, u3x_sam_4, &haj,
50, &boq, // +<->-
51, &out, // +<->+
u3x_sam_12, &wik,
u3x_sam_13, &key,
u3x_sam_14, &wid,
u3x_sam_15, &dat, 0)) ||
(c3n == u3ud(boq)) ||
(c3n == u3a_is_cat(boq)) ||
(c3n == u3ud(out)) ||
(c3n == u3a_is_cat(out)) ||
(c3n == u3ud(wik)) ||
(c3n == u3a_is_cat(wik)) ||
(c3n == u3ud(key)) ||
(c3n == u3ud(wid)) ||
(c3n == u3a_is_cat(wid)) ||
(c3n == u3ud(dat)) )
{
return u3m_bail(c3__exit);
} else {
return u3qe_hmac(haj, boq, out, wik, key, wid, dat);
}
}