pub/, progs/: Add support for X448 key exchange, defined in RFC7748.

[catacomb] / progs / cc-kem.c

diff --git a/progs/cc-kem.c b/progs/cc-kem.c
index 71c89e4..5b0cbf7 100644 (file)
--- a/progs/cc-kem.c
+++ b/progs/cc-kem.c
@@ -44,6 +44,7 @@
 #include "dh.h"
 #include "rsa.h"
 #include "x25519.h"
+#include "x448.h"
 
 #include "rmd160.h"
 #include "blowfish-cbc.h"
@@ -668,6 +669,71 @@ static const kemops x25519_decops = {
   x25519_encinit, x25519_decdoit, x25519_deccheck, x25519_encdestroy
 };
 
+/* --- X448 --- */
+
+static kem *x448_encinit(key *k, void *kd) { return (CREATE(kem)); }
+static void x448_encdestroy(kem *k) { DESTROY(k); }
+
+static const char *x448_enccheck(kem *k)
+{
+  x448_pub *kd = k->kd;
+
+  if (kd->pub.sz != X448_PUBSZ)
+    return ("incorrect X448 public key length");
+  return (0);
+}
+
+static int x448_encdoit(kem *k, dstr *d, ghash *h)
+{
+  octet t[X448_KEYSZ], z[X448_OUTSZ];
+  x448_pub *kd = k->kd;
+
+  rand_get(RAND_GLOBAL, t, sizeof(t));
+  dstr_ensure(d, X448_PUBSZ);
+  x448((octet *)d->buf, t, x448_base);
+  x448(z, t, kd->pub.k);
+  d->len += X448_PUBSZ;
+  GH_HASH(h, d->buf, X448_PUBSZ);
+  GH_HASH(h, z, X448_OUTSZ);
+  return (0);
+}
+
+static const char *x448_deccheck(kem *k)
+{
+  x448_priv *kd = k->kd;
+
+  if (kd->priv.sz != X448_KEYSZ)
+    return ("incorrect X448 private key length");
+  if (kd->pub.sz != X448_PUBSZ)
+    return ("incorrect X448 public key length");
+  return (0);
+}
+
+static int x448_decdoit(kem *k, dstr *d, ghash *h)
+{
+  octet z[X448_OUTSZ];
+  x448_priv *kd = k->kd;
+  int rc = -1;
+
+  if (d->len != X448_PUBSZ) goto done;
+  x448(z, kd->priv.k, (const octet *)d->buf);
+  GH_HASH(h, d->buf, X448_PUBSZ);
+  GH_HASH(h, z, X448_OUTSZ);
+  rc = 0;
+done:
+  return (rc);
+}
+
+static const kemops x448_encops = {
+  x448_pubfetch, sizeof(x448_pub),
+  x448_encinit, x448_encdoit, x448_enccheck, x448_encdestroy
+};
+
+static const kemops x448_decops = {
+  x448_privfetch, sizeof(x448_priv),
+  x448_encinit, x448_decdoit, x448_deccheck, x448_encdestroy
+};
+
 /* --- Symmetric --- */
 
 typedef struct symm_ctx {
@@ -737,6 +803,7 @@ const struct kemtab kemtab[] = {
   { "bindh",   &bindh_encops,  &bindh_decops },
   { "ec",      &ec_encops,     &ec_decops },
   { "x25519",  &x25519_encops, &x25519_decops },
+  { "x448",    &x448_encops,   &x448_decops },
   { "symm",    &symm_encops,   &symm_decops },
   { 0,         0,              0 }
 };