Replaced system SQLite with SQLCipher to support encrypted database

Sources/DataLiteC/libtomcrypt/pk/ecc/ecc_shared_secret.c

@@ -0,0 +1,66 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+#include "tomcrypt_private.h"
+
+/**
+  @file ecc_shared_secret.c
+  ECC Crypto, Tom St Denis
+*/
+
+#ifdef LTC_MECC
+
+/**
+  Create an ECC shared secret between two keys
+  @param private_key      The private ECC key
+  @param public_key       The public key
+  @param out              [out] Destination of the shared secret (Conforms to EC-DH from ANSI X9.63)
+  @param outlen           [in/out] The max size and resulting size of the shared secret
+  @return CRYPT_OK if successful
+*/
+int ecc_shared_secret(const ecc_key *private_key, const ecc_key *public_key,
+                      unsigned char *out, unsigned long *outlen)
+{
+   unsigned long  x;
+   ecc_point     *result;
+   void          *prime, *a;
+   int            err;
+
+   LTC_ARGCHK(private_key != NULL);
+   LTC_ARGCHK(public_key  != NULL);
+   LTC_ARGCHK(out         != NULL);
+   LTC_ARGCHK(outlen      != NULL);
+
+   /* type valid? */
+   if (private_key->type != PK_PRIVATE) {
+      return CRYPT_PK_NOT_PRIVATE;
+   }
+
+   /* make new point */
+   result = ltc_ecc_new_point();
+   if (result == NULL) {
+      return CRYPT_MEM;
+   }
+
+   prime = private_key->dp.prime;
+   a     = private_key->dp.A;
+
+   if ((err = ltc_mp.ecc_ptmul(private_key->k, &public_key->pubkey, result, a, prime, 1)) != CRYPT_OK)   { goto done; }
+
+   x = (unsigned long)ltc_mp_unsigned_bin_size(prime);
+   if (*outlen < x) {
+      *outlen = x;
+      err = CRYPT_BUFFER_OVERFLOW;
+      goto done;
+   }
+   zeromem(out, x);
+   if ((err = ltc_mp_to_unsigned_bin(result->x, out + (x - ltc_mp_unsigned_bin_size(result->x))))   != CRYPT_OK) { goto done; }
+
+   err     = CRYPT_OK;
+   *outlen = x;
+done:
+   ltc_ecc_del_point(result);
+   return err;
+}
+
+#endif