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