1 files changed, 94 insertions, 0 deletions
diff --git a/vere/pkg/noun/jets/e/hmac.c b/vere/pkg/noun/jets/e/hmac.c
new file mode 100644
index 0000000..b14ec1e
--- /dev/null
+++ b/vere/pkg/noun/jets/e/hmac.c
@@ -0,0 +1,94 @@
+/// @file
+
+#include "jets/k.h"
+#include "jets/q.h"
+#include "jets/w.h"
+
+#include "noun.h"
+
+
+  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)
+  {
+    u3_assert(_(u3a_is_cat(boq)) && _(u3a_is_cat(wik)) && _(u3a_is_cat(wid)));
+
+    // prep the hashing gate
+    u3j_site sit_u;
+    u3j_gate_prep(&sit_u, u3k(haj));
+
+    // 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 = u3j_gate_slam(&sit_u, 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), dat);
+    u3_atom innhaj = u3j_gate_slam(&sit_u, 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 = u3j_gate_slam(&sit_u, u3nc((out + boq), outmsg));
+
+    u3j_gate_lose(&sit_u);
+    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);
+    }
+  }