csidh: adds interface with POD types only

csidh/ref/csidh/csidh.c

@@ -5,6 +5,8 @@
 #include "csidh.h"
 #include "rng.h"
 
+#include <stdio.h>
+
 /* specific to p, should perhaps be somewhere else */
 const unsigned primes[num_primes] = {
       3,   5,   7,  11,  13,  17,  19,  23,  29,  31,  37,  41,  43,  47,  53,  59,
@@ -218,3 +220,59 @@ bool csidh(public_key *out, public_key const *in, private_key const *priv)
     return true;
 }
 
+/// Public API
+
+void export_public(uint8_t *out, const public_key *pub) {
+    for(size_t i=0; i<64; i++) {
+        size_t j = i / 8;
+        size_t k = i % 8;
+        out[i] = ((uint64_t)pub->A.x.c[j] >> (8*k)) & 0xFF;
+    }
+}
+
+void import_public(public_key *pub, const uint8_t *out) {
+    for (size_t i=0; i<64; i++) {
+        size_t j = i / 8;
+        size_t k = i%8;
+        uint64_t tmp = out[i];
+        pub->A.x.c[j] |= tmp << (8*k);
+    }
+}
+
+void export_private(uint8_t *out, const private_key *prv) {
+    for(size_t i=0; i<37; i++) {
+        out[i] = (uint8_t) prv->e[i];
+    }
+}
+
+void import_private(private_key *prv, const uint8_t *out) {
+    for (size_t i=0; i<37; i++) {
+        prv->e[i] = (int8_t) out[i];
+    }
+}
+
+void keygen_prv(uint8_t private[37]) {
+    private_key priv;
+    csidh_private(&priv);
+    export_private(&private[0], &priv);
+}
+
+void keygen_pub(uint8_t public[64], const uint8_t private[37]) {
+    private_key prv1 = {0};
+    public_key pub1 = {0};
+    import_private(&prv1, &private[0]);
+    csidh(&pub1, &base, &prv1);
+    export_public(&public[0], &pub1);
+}
+
+void derive(uint8_t result[64], const uint8_t public[64], const uint8_t private[37]) {
+    public_key pub = {0};
+    public_key ss = {0};
+    private_key prv;
+
+    import_private(&prv, &private[0]);
+    import_public(&pub, &public[0]);
+
+    csidh(&ss, &pub, &prv);
+    export_public(&result[0], &ss);
+}

csidh/ref/csidh/csidh.h

@@ -23,4 +23,12 @@ extern const public_key base;
 void csidh_private(private_key *priv);
 bool csidh(public_key *out, public_key const *in, private_key const *priv);
 
+void keygen_prv(uint8_t private[37]);
+void keygen_pub(uint8_t public[64], const uint8_t private[37]);
+void derive(uint8_t result[64], const uint8_t public[64], const uint8_t private_key[37]);
+
+void export_public(uint8_t *out, const public_key *pub);
+void import_public(public_key *pub, const uint8_t *out);
+void export_private(uint8_t *out, const private_key *prv);
+void import_private(private_key *prv, const uint8_t *out);
 #endif