Replaced system SQLite with SQLCipher to support encrypted database

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

@@ -0,0 +1,62 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+#include "tomcrypt_private.h"
+
+#ifdef LTC_MECC
+
+/** Returns whether [x,y] is a point on curve defined by dp
+  @param dp     curve parameters
+  @param x      x point coordinate
+  @param y      y point coordinate
+  @return CRYPT_OK if valid
+*/
+
+int ltc_ecc_is_point(const ltc_ecc_dp *dp, void *x, void *y)
+{
+  void *prime, *a, *b, *t1, *t2;
+  int err;
+
+  prime = dp->prime;
+  b     = dp->B;
+  a     = dp->A;
+
+  if ((err = ltc_mp_init_multi(&t1, &t2, LTC_NULL)) != CRYPT_OK)  return err;
+
+  /* compute y^2 */
+  if ((err = ltc_mp_sqr(y, t1)) != CRYPT_OK)                  goto cleanup;
+
+  /* compute x^3 */
+  if ((err = ltc_mp_sqr(x, t2)) != CRYPT_OK)                  goto cleanup;
+  if ((err = ltc_mp_mod(t2, prime, t2)) != CRYPT_OK)          goto cleanup;
+  if ((err = ltc_mp_mul(x, t2, t2)) != CRYPT_OK)              goto cleanup;
+
+  /* compute y^2 - x^3 */
+  if ((err = ltc_mp_sub(t1, t2, t1)) != CRYPT_OK)             goto cleanup;
+
+  /* compute y^2 - x^3 - a*x */
+  if ((err = ltc_mp_submod(prime, a, prime, t2)) != CRYPT_OK) goto cleanup;
+  if ((err = ltc_mp_mulmod(t2, x, prime, t2)) != CRYPT_OK)    goto cleanup;
+  if ((err = ltc_mp_addmod(t1, t2, prime, t1)) != CRYPT_OK)   goto cleanup;
+
+  /* adjust range (0, prime) */
+  while (ltc_mp_cmp_d(t1, 0) == LTC_MP_LT) {
+     if ((err = ltc_mp_add(t1, prime, t1)) != CRYPT_OK)       goto cleanup;
+  }
+  while (ltc_mp_cmp(t1, prime) != LTC_MP_LT) {
+     if ((err = ltc_mp_sub(t1, prime, t1)) != CRYPT_OK)       goto cleanup;
+  }
+
+  /* compare to b */
+  if (ltc_mp_cmp(t1, b) != LTC_MP_EQ) {
+     err = CRYPT_INVALID_PACKET;
+  } else {
+     err = CRYPT_OK;
+  }
+
+cleanup:
+  ltc_mp_deinit_multi(t1, t2, LTC_NULL);
+  return err;
+}
+
+#endif