diff --git a/include/tinycrypt/ecc.h b/include/tinycrypt/ecc.h
index 9c53f3e7e..2da74b3c0 100644
--- a/include/tinycrypt/ecc.h
+++ b/include/tinycrypt/ecc.h
@@ -111,6 +111,7 @@ typedef uint64_t uECC_dword_t;
 #define NUM_ECC_WORDS 8
 /* Number of bytes to represent an element of the the curve p-256: */
 #define NUM_ECC_BYTES (uECC_WORD_SIZE*NUM_ECC_WORDS)
+#define NUM_ECC_BITS 256
 
 /* structure that represents an elliptic curve (e.g. p256):*/
 struct uECC_Curve_t;
@@ -282,32 +283,19 @@ int uECC_compute_public_key(const uint8_t *private_key,
 uECC_word_t EccPoint_compute_public_key(uECC_word_t *result,
 					uECC_word_t *private_key, uECC_Curve curve);
 
-/*
- * @brief Regularize the bitcount for the private key so that attackers cannot
- * use a side channel attack to learn the number of leading zeros.
- * @return Regularized k
- * @param k IN -- private-key
- * @param k0 IN/OUT -- regularized k
- * @param k1 IN/OUT -- regularized k
- * @param curve IN -- elliptic curve
- */
-uECC_word_t regularize_k(const uECC_word_t * const k, uECC_word_t *k0,
-			 uECC_word_t *k1, uECC_Curve curve);
-
 /*
  * @brief Point multiplication algorithm using Montgomery's ladder with co-Z
  * coordinates. See http://eprint.iacr.org/2011/338.pdf.
+ * Uses scalar regularization and coordinate randomization (if a global RNG
+ * function is set) in order to protect against some side channel attacks.
  * @note Result may overlap point.
  * @param result OUT -- returns scalar*point
  * @param point IN -- elliptic curve point
  * @param scalar IN -- scalar
- * @param initial_Z IN -- initial value for z
- * @param num_bits IN -- number of bits in scalar
  * @param curve IN -- elliptic curve
  */
-void EccPoint_mult(uECC_word_t * result, const uECC_word_t * point,
-		   const uECC_word_t * scalar, const uECC_word_t * initial_Z,
-		   bitcount_t num_bits, uECC_Curve curve);
+int EccPoint_mult_safer(uECC_word_t * result, const uECC_word_t * point,
+			const uECC_word_t * scalar, uECC_Curve curve);
 
 /*
  * @brief Constant-time comparison to zero - secure way to compare long integers
@@ -315,7 +303,7 @@ void EccPoint_mult(uECC_word_t * result, const uECC_word_t * point,
  * @param num_words IN -- number of words in the vli
  * @return 1 if vli == 0, 0 otherwise.
  */
-uECC_word_t uECC_vli_isZero(const uECC_word_t *vli, wordcount_t num_words);
+uECC_word_t uECC_vli_isZero(const uECC_word_t *vli);
 
 /*
  * @brief Check if 'point' is the point at infinity
@@ -332,8 +320,7 @@ uECC_word_t EccPoint_isZero(const uECC_word_t *point, uECC_Curve curve);
  * @param num_words IN -- number of words
  * @return the sign of left - right
  */
-cmpresult_t uECC_vli_cmp(const uECC_word_t *left, const uECC_word_t *right,
-			 wordcount_t num_words);
+cmpresult_t uECC_vli_cmp(const uECC_word_t *left, const uECC_word_t *right);
 
 /*
  * @brief computes sign of left - right, not in constant time.
@@ -343,8 +330,7 @@ cmpresult_t uECC_vli_cmp(const uECC_word_t *left, const uECC_word_t *right,
  * @param num_words IN -- number of words
  * @return the sign of left - right
  */
-cmpresult_t uECC_vli_cmp_unsafe(const uECC_word_t *left, const uECC_word_t *right,
-				wordcount_t num_words);
+cmpresult_t uECC_vli_cmp_unsafe(const uECC_word_t *left, const uECC_word_t *right);
 
 /*
  * @brief Computes result = (left - right) % mod.
@@ -357,8 +343,7 @@ cmpresult_t uECC_vli_cmp_unsafe(const uECC_word_t *left, const uECC_word_t *righ
  * @param num_words IN -- number of words
  */
 void uECC_vli_modSub(uECC_word_t *result, const uECC_word_t *left,
-		     const uECC_word_t *right, const uECC_word_t *mod,
-		     wordcount_t num_words);
+		     const uECC_word_t *right, const uECC_word_t *mod);
 
 /*
  * @brief Computes P' = (x1', y1', Z3), P + Q = (x3, y3, Z3) or
@@ -380,8 +365,7 @@ void XYcZ_add(uECC_word_t * X1, uECC_word_t * Y1, uECC_word_t * X2,
  * @param Z IN -- z value
  * @param curve IN -- elliptic curve
  */
-void apply_z(uECC_word_t * X1, uECC_word_t * Y1, const uECC_word_t * const Z,
-	     uECC_Curve curve);
+void apply_z(uECC_word_t * X1, uECC_word_t * Y1, const uECC_word_t * const Z);
 
 /*
  * @brief Check if bit is set.
@@ -402,7 +386,7 @@ uECC_word_t uECC_vli_testBit(const uECC_word_t *vli, bitcount_t bit);
  * @warning Currently only designed to work for curve_p or curve_n.
  */
 void uECC_vli_mmod(uECC_word_t *result, uECC_word_t *product,
-		   const uECC_word_t *mod, wordcount_t num_words);
+		   const uECC_word_t *mod);
 
 /*
  * @brief Computes modular product (using curve->mmod_fast)
@@ -412,7 +396,7 @@ void uECC_vli_mmod(uECC_word_t *result, uECC_word_t *product,
  * @param curve IN -- elliptic curve
  */
 void uECC_vli_modMult_fast(uECC_word_t *result, const uECC_word_t *left,
-			   const uECC_word_t *right, uECC_Curve curve);
+			   const uECC_word_t *right);
 
 /*
  * @brief Computes result = left - right.
@@ -424,7 +408,7 @@ void uECC_vli_modMult_fast(uECC_word_t *result, const uECC_word_t *left,
  * @return borrow
  */
 uECC_word_t uECC_vli_sub(uECC_word_t *result, const uECC_word_t *left,
-			 const uECC_word_t *right, wordcount_t num_words);
+			 const uECC_word_t *right);
 
 /*
  * @brief Constant-time comparison function(secure way to compare long ints)
@@ -433,8 +417,7 @@ uECC_word_t uECC_vli_sub(uECC_word_t *result, const uECC_word_t *left,
  * @param num_words IN -- number of words
  * @return Returns 0 if left == right, 1 otherwise.
  */
-uECC_word_t uECC_vli_equal(const uECC_word_t *left, const uECC_word_t *right,
-			   wordcount_t num_words);
+uECC_word_t uECC_vli_equal(const uECC_word_t *left, const uECC_word_t *right);
 
 /*
  * @brief Computes (left * right) % mod
@@ -445,8 +428,7 @@ uECC_word_t uECC_vli_equal(const uECC_word_t *left, const uECC_word_t *right,
  * @param num_words IN -- number of words
  */
 void uECC_vli_modMult(uECC_word_t *result, const uECC_word_t *left,
-		      const uECC_word_t *right, const uECC_word_t *mod,
-	              wordcount_t num_words);
+		      const uECC_word_t *right, const uECC_word_t *mod);
 
 /*
  * @brief Computes (1 / input) % mod
@@ -458,7 +440,7 @@ void uECC_vli_modMult(uECC_word_t *result, const uECC_word_t *left,
  * @param num_words -- number of words
  */
 void uECC_vli_modInv(uECC_word_t *result, const uECC_word_t *input,
-		     const uECC_word_t *mod, wordcount_t num_words);
+		     const uECC_word_t *mod);
 
 /*
  * @brief Sets dest = src.
@@ -466,8 +448,7 @@ void uECC_vli_modInv(uECC_word_t *result, const uECC_word_t *input,
  * @param src IN --  origin buffer
  * @param num_words IN -- number of words
  */
-void uECC_vli_set(uECC_word_t *dest, const uECC_word_t *src,
-		  wordcount_t num_words);
+void uECC_vli_set(uECC_word_t *dest, const uECC_word_t *src);
 
 /*
  * @brief Computes (left + right) % mod.
@@ -480,8 +461,7 @@ void uECC_vli_set(uECC_word_t *dest, const uECC_word_t *src,
  * @param num_words IN -- number of words
  */
 void uECC_vli_modAdd(uECC_word_t *result,  const uECC_word_t *left,
-    		     const uECC_word_t *right, const uECC_word_t *mod,
-   		     wordcount_t num_words);
+    		     const uECC_word_t *right, const uECC_word_t *mod);
 
 /*
  * @brief Counts the number of bits required to represent vli.
@@ -489,15 +469,14 @@ void uECC_vli_modAdd(uECC_word_t *result,  const uECC_word_t *left,
  * @param max_words IN -- number of words
  * @return number of bits in given vli
  */
-bitcount_t uECC_vli_numBits(const uECC_word_t *vli, 
-			    const wordcount_t max_words);
+bitcount_t uECC_vli_numBits(const uECC_word_t *vli);
 
 /*
  * @brief Erases (set to 0) vli
  * @param vli IN -- very long integer
  * @param num_words IN -- number of words
  */
-void uECC_vli_clear(uECC_word_t *vli, wordcount_t num_words);
+void uECC_vli_clear(uECC_word_t *vli);
 
 /*
  * @brief check if it is a valid point in the curve
diff --git a/tinycrypt/ecc.c b/tinycrypt/ecc.c
index cef1469ee..d01c67617 100644
--- a/tinycrypt/ecc.c
+++ b/tinycrypt/ecc.c
@@ -65,6 +65,7 @@
 
 #if defined(MBEDTLS_USE_TINYCRYPT)
 #include <tinycrypt/ecc.h>
+#include "mbedtls/platform_util.h"
 #include <string.h>
 
 /* IMPORTANT: Make sure a cryptographically-secure PRNG is set and the platform
@@ -95,19 +96,19 @@ int uECC_curve_public_key_size(uECC_Curve curve)
 	return 2 * curve->num_bytes;
 }
 
-void uECC_vli_clear(uECC_word_t *vli, wordcount_t num_words)
+void uECC_vli_clear(uECC_word_t *vli)
 {
 	wordcount_t i;
-	for (i = 0; i < num_words; ++i) {
+	for (i = 0; i < NUM_ECC_WORDS; ++i) {
 		 vli[i] = 0;
 	}
 }
 
-uECC_word_t uECC_vli_isZero(const uECC_word_t *vli, wordcount_t num_words)
+uECC_word_t uECC_vli_isZero(const uECC_word_t *vli)
 {
 	uECC_word_t bits = 0;
 	wordcount_t i;
-	for (i = 0; i < num_words; ++i) {
+	for (i = 0; i < NUM_ECC_WORDS; ++i) {
 		bits |= vli[i];
 	}
 	return (bits == 0);
@@ -120,27 +121,25 @@ uECC_word_t uECC_vli_testBit(const uECC_word_t *vli, bitcount_t bit)
 }
 
 /* Counts the number of words in vli. */
-static wordcount_t vli_numDigits(const uECC_word_t *vli,
-				 const wordcount_t max_words)
+static wordcount_t vli_numDigits(const uECC_word_t *vli)
 {
 
 	wordcount_t i;
 	/* Search from the end until we find a non-zero digit. We do it in reverse
 	 * because we expect that most digits will be nonzero. */
-	for (i = max_words - 1; i >= 0 && vli[i] == 0; --i) {
+	for (i = NUM_ECC_WORDS - 1; i >= 0 && vli[i] == 0; --i) {
 	}
 
 	return (i + 1);
 }
 
-bitcount_t uECC_vli_numBits(const uECC_word_t *vli,
-			    const wordcount_t max_words)
+bitcount_t uECC_vli_numBits(const uECC_word_t *vli)
 {
 
 	uECC_word_t i;
 	uECC_word_t digit;
 
-	wordcount_t num_digits = vli_numDigits(vli, max_words);
+	wordcount_t num_digits = vli_numDigits(vli);
 	if (num_digits == 0) {
 		return 0;
 	}
@@ -153,23 +152,21 @@ bitcount_t uECC_vli_numBits(const uECC_word_t *vli,
 	return (((bitcount_t)(num_digits - 1) << uECC_WORD_BITS_SHIFT) + i);
 }
 
-void uECC_vli_set(uECC_word_t *dest, const uECC_word_t *src,
-		  wordcount_t num_words)
+void uECC_vli_set(uECC_word_t *dest, const uECC_word_t *src)
 {
 	wordcount_t i;
 
-	for (i = 0; i < num_words; ++i) {
+	for (i = 0; i < NUM_ECC_WORDS; ++i) {
 		dest[i] = src[i];
   	}
 }
 
 cmpresult_t uECC_vli_cmp_unsafe(const uECC_word_t *left,
-				const uECC_word_t *right,
-				wordcount_t num_words)
+				const uECC_word_t *right)
 {
 	wordcount_t i;
 
-	for (i = num_words - 1; i >= 0; --i) {
+	for (i = NUM_ECC_WORDS - 1; i >= 0; --i) {
 		if (left[i] > right[i]) {
 			return 1;
 		} else if (left[i] < right[i]) {
@@ -179,14 +176,13 @@ cmpresult_t uECC_vli_cmp_unsafe(const uECC_word_t *left,
 	return 0;
 }
 
-uECC_word_t uECC_vli_equal(const uECC_word_t *left, const uECC_word_t *right,
-			   wordcount_t num_words)
+uECC_word_t uECC_vli_equal(const uECC_word_t *left, const uECC_word_t *right)
 {
 
 	uECC_word_t diff = 0;
 	wordcount_t i;
 
-	for (i = num_words - 1; i >= 0; --i) {
+	for (i = NUM_ECC_WORDS - 1; i >= 0; --i) {
 		diff |= (left[i] ^ right[i]);
 	}
 	return !(diff == 0);
@@ -200,11 +196,11 @@ uECC_word_t cond_set(uECC_word_t p_true, uECC_word_t p_false, unsigned int cond)
 /* Computes result = left - right, returning borrow, in constant time.
  * Can modify in place. */
 uECC_word_t uECC_vli_sub(uECC_word_t *result, const uECC_word_t *left,
-			 const uECC_word_t *right, wordcount_t num_words)
+			 const uECC_word_t *right)
 {
 	uECC_word_t borrow = 0;
 	wordcount_t i;
-	for (i = 0; i < num_words; ++i) {
+	for (i = 0; i < NUM_ECC_WORDS; ++i) {
 		uECC_word_t diff = left[i] - right[i] - borrow;
 		uECC_word_t val = (diff > left[i]);
 		borrow = cond_set(val, borrow, (diff != left[i]));
@@ -217,11 +213,11 @@ uECC_word_t uECC_vli_sub(uECC_word_t *result, const uECC_word_t *left,
 /* Computes result = left + right, returning carry, in constant time.
  * Can modify in place. */
 static uECC_word_t uECC_vli_add(uECC_word_t *result, const uECC_word_t *left,
-				const uECC_word_t *right, wordcount_t num_words)
+				const uECC_word_t *right)
 {
 	uECC_word_t carry = 0;
 	wordcount_t i;
-	for (i = 0; i < num_words; ++i) {
+	for (i = 0; i < NUM_ECC_WORDS; ++i) {
 		uECC_word_t sum = left[i] + right[i] + carry;
 		uECC_word_t val = (sum < left[i]);
 		carry = cond_set(val, carry, (sum != left[i]));
@@ -230,22 +226,21 @@ static uECC_word_t uECC_vli_add(uECC_word_t *result, const uECC_word_t *left,
 	return carry;
 }
 
-cmpresult_t uECC_vli_cmp(const uECC_word_t *left, const uECC_word_t *right,
-			 wordcount_t num_words)
+cmpresult_t uECC_vli_cmp(const uECC_word_t *left, const uECC_word_t *right)
 {
 	uECC_word_t tmp[NUM_ECC_WORDS];
-	uECC_word_t neg = !!uECC_vli_sub(tmp, left, right, num_words);
-	uECC_word_t equal = uECC_vli_isZero(tmp, num_words);
+	uECC_word_t neg = !!uECC_vli_sub(tmp, left, right);
+	uECC_word_t equal = uECC_vli_isZero(tmp);
 	return (!equal - 2 * neg);
 }
 
 /* Computes vli = vli >> 1. */
-static void uECC_vli_rshift1(uECC_word_t *vli, wordcount_t num_words)
+static void uECC_vli_rshift1(uECC_word_t *vli)
 {
 	uECC_word_t *end = vli;
 	uECC_word_t carry = 0;
 
-	vli += num_words;
+	vli += NUM_ECC_WORDS;
 	while (vli-- > end) {
 		uECC_word_t temp = *vli;
 		*vli = (temp >> 1) | carry;
@@ -253,6 +248,16 @@ static void uECC_vli_rshift1(uECC_word_t *vli, wordcount_t num_words)
 	}
 }
 
+/* Compute a * b + r, where r is a double-word with high-order word r1 and
+ * low-order word r0, and store the result in the same double-word (r1, r0),
+ * with the carry bit stored in r2.
+ *
+ * (r2, r1, r0) = a * b + (r1, r0):
+ * [in] a, b: operands to be multiplied
+ * [in] r0, r1: low and high-order words of operand to add
+ * [out] r0, r1: low and high-order words of the result
+ * [out] r2: carry
+ */
 static void muladd(uECC_word_t a, uECC_word_t b, uECC_word_t *r0,
 		   uECC_word_t *r1, uECC_word_t *r2)
 {
@@ -266,15 +271,84 @@ static void muladd(uECC_word_t a, uECC_word_t b, uECC_word_t *r0,
 
 }
 
-/* Computes result = left * right. Result must be 2 * num_words long. */
-static void uECC_vli_mult(uECC_word_t *result, const uECC_word_t *left,
-			  const uECC_word_t *right, wordcount_t num_words)
+/* State for implementing random delays in uECC_vli_mult_rnd().
+ *
+ * The state is initialized by randomizing delays and setting i = 0.
+ * Each call to uECC_vli_mult_rnd() uses one byte of delays and increments i.
+ *
+ * Randomized vli multiplication is used only for point operations
+ * (XYcZ_add_rnd() * and XYcZ_addC_rnd()) in scalar multiplication
+ * (ECCPoint_mult()). Those go in pair, and each pair does 14 calls to
+ * uECC_vli_mult_rnd() (6 in XYcZ_add_rnd() and 8 in XYcZ_addC_rnd(),
+ * indirectly through uECC_vli_modMult_rnd().
+ *
+ * Considering this, in order to minimize the number of calls to the RNG
+ * (which impact performance) while keeping the size of the structure low,
+ * make room for 14 randomized vli mults, which corresponds to one step in the
+ * scalar multiplication routine.
+ */
+typedef struct {
+	uint8_t i;
+	uint8_t delays[14];
+} ecc_wait_state_t;
+
+/*
+ * Reset wait_state so that it's ready to be used.
+ */
+void ecc_wait_state_reset(ecc_wait_state_t *ws)
+{
+	if (ws == NULL)
+		return;
+
+	ws->i = 0;
+	g_rng_function(ws->delays, sizeof(ws->delays));
+}
+
+/* Computes result = left * right. Result must be 2 * num_words long.
+ *
+ * As a counter-measure against horizontal attacks, add noise by performing
+ * a random number of extra computations performing random additional accesses
+ * to limbs of the input.
+ *
+ * Each of the two actual computation loops is surrounded by two
+ * similar-looking waiting loops, to make the beginning and end of the actual
+ * computation harder to spot.
+ *
+ * We add 4 waiting loops of between 0 and 3 calls to muladd() each. That
+ * makes an average of 6 extra calls. Compared to the main computation which
+ * makes 64 such calls, this represents an average performance degradation of
+ * less than 10%.
+ *
+ * Compared to the original uECC_vli_mult(), loose the num_words argument as we
+ * know it's always 8. This saves a bit of code size and execution speed.
+ */
+static void uECC_vli_mult_rnd(uECC_word_t *result, const uECC_word_t *left,
+			      const uECC_word_t *right, ecc_wait_state_t *s)
 {
 
 	uECC_word_t r0 = 0;
 	uECC_word_t r1 = 0;
 	uECC_word_t r2 = 0;
 	wordcount_t i, k;
+	const uint8_t num_words = NUM_ECC_WORDS;
+
+	/* Fetch 8 bit worth of delay from the state; 0 if we have no state */
+	uint8_t delays = s ? s->delays[s->i++] : 0;
+	uECC_word_t rr0 = 0, rr1 = 0;
+	volatile uECC_word_t r;
+
+	/* Mimic start of next loop: k in [0, 3] */
+	k = 0 + (delays & 0x03);
+	delays >>= 2;
+	/* k = 0 -> i in [1, 0] -> 0 extra muladd;
+	 * k = 3 -> i in [1, 3] -> 3 extra muladd */
+	for (i = 1; i <= k; ++i) {
+		muladd(left[i], right[k - i], &rr0, &rr1, &r2);
+	}
+	r = rr0;
+	rr0 = rr1;
+	rr1 = r2;
+	r2 = 0;
 
 	/* Compute each digit of result in sequence, maintaining the carries. */
 	for (k = 0; k < num_words; ++k) {
@@ -289,6 +363,32 @@ static void uECC_vli_mult(uECC_word_t *result, const uECC_word_t *left,
 		r2 = 0;
 	}
 
+	/* Mimic end of previous loop: k in [4, 7] */
+	k = 4 + (delays & 0x03);
+	delays >>= 2;
+	/* k = 4 -> i in [5, 4] -> 0 extra muladd;
+	 * k = 7 -> i in [5, 7] -> 3 extra muladd */
+	for (i = 5; i <= k; ++i) {
+		muladd(left[i], right[k - i], &rr0, &rr1, &r2);
+	}
+	r = rr0;
+	rr0 = rr1;
+	rr1 = r2;
+	r2 = 0;
+
+	/* Mimic start of next loop: k in [8, 11] */
+	k = 11 - (delays & 0x03);
+	delays >>= 2;
+	/* k =  8 -> i in [5, 7] -> 3 extra muladd;
+	 * k = 11 -> i in [8, 7] -> 0 extra muladd */
+	for (i = (k + 5) - num_words; i < num_words; ++i) {
+		muladd(left[i], right[k - i], &rr0, &rr1, &r2);
+	}
+	r = rr0;
+	rr0 = rr1;
+	rr1 = r2;
+	r2 = 0;
+
 	for (k = num_words; k < num_words * 2 - 1; ++k) {
 
 		for (i = (k + 1) - num_words; i < num_words; ++i) {
@@ -299,57 +399,73 @@ static void uECC_vli_mult(uECC_word_t *result, const uECC_word_t *left,
 		r1 = r2;
 		r2 = 0;
 	}
+
 	result[num_words * 2 - 1] = r0;
+
+	/* Mimic end of previous loop: k in [12, 15] */
+	k = 15 - (delays & 0x03);
+	delays >>= 2;
+	/* k = 12 -> i in [5, 7] -> 3 extra muladd;
+	 * k = 15 -> i in [8, 7] -> 0 extra muladd */
+	for (i = (k + 1) - num_words; i < num_words; ++i) {
+		muladd(left[i], right[k - i], &rr0, &rr1, &r2);
+	}
+	r = rr0;
+	rr0 = rr1;
+	rr1 = r2;
+	r2 = 0;
+
+	/* avoid warning that r is set but not used */
+	(void) r;
 }
 
 void uECC_vli_modAdd(uECC_word_t *result, const uECC_word_t *left,
-		     const uECC_word_t *right, const uECC_word_t *mod,
-		     wordcount_t num_words)
+		     const uECC_word_t *right, const uECC_word_t *mod)
 {
-	uECC_word_t carry = uECC_vli_add(result, left, right, num_words);
-	if (carry || uECC_vli_cmp_unsafe(mod, result, num_words) != 1) {
+	uECC_word_t carry = uECC_vli_add(result, left, right);
+	if (carry || uECC_vli_cmp_unsafe(mod, result) != 1) {
 	/* result > mod (result = mod + remainder), so subtract mod to get
 	 * remainder. */
-		uECC_vli_sub(result, result, mod, num_words);
+		uECC_vli_sub(result, result, mod);
 	}
 }
 
 void uECC_vli_modSub(uECC_word_t *result, const uECC_word_t *left,
-		     const uECC_word_t *right, const uECC_word_t *mod,
-		     wordcount_t num_words)
+		     const uECC_word_t *right, const uECC_word_t *mod)
 {
-	uECC_word_t l_borrow = uECC_vli_sub(result, left, right, num_words);
+	uECC_word_t l_borrow = uECC_vli_sub(result, left, right);
 	if (l_borrow) {
 		/* In this case, result == -diff == (max int) - diff. Since -x % d == d - x,
 		 * we can get the correct result from result + mod (with overflow). */
-		uECC_vli_add(result, result, mod, num_words);
+		uECC_vli_add(result, result, mod);
 	}
 }
 
 /* Computes result = product % mod, where product is 2N words long. */
 /* Currently only designed to work for curve_p or curve_n. */
 void uECC_vli_mmod(uECC_word_t *result, uECC_word_t *product,
-    		   const uECC_word_t *mod, wordcount_t num_words)
+    		   const uECC_word_t *mod)
 {
 	uECC_word_t mod_multiple[2 * NUM_ECC_WORDS];
 	uECC_word_t tmp[2 * NUM_ECC_WORDS];
 	uECC_word_t *v[2] = {tmp, product};
 	uECC_word_t index;
+	const wordcount_t num_words = NUM_ECC_WORDS;
 
 	/* Shift mod so its highest set bit is at the maximum position. */
 	bitcount_t shift = (num_words * 2 * uECC_WORD_BITS) -
-			   uECC_vli_numBits(mod, num_words);
+			   uECC_vli_numBits(mod);
 	wordcount_t word_shift = shift / uECC_WORD_BITS;
 	wordcount_t bit_shift = shift % uECC_WORD_BITS;
 	uECC_word_t carry = 0;
-	uECC_vli_clear(mod_multiple, word_shift);
+	uECC_vli_clear(mod_multiple);
 	if (bit_shift > 0) {
 		for(index = 0; index < (uECC_word_t)num_words; ++index) {
 			mod_multiple[word_shift + index] = (mod[index] << bit_shift) | carry;
 			carry = mod[index] >> (uECC_WORD_BITS - bit_shift);
 		}
 	} else {
-		uECC_vli_set(mod_multiple + word_shift, mod, num_words);
+		uECC_vli_set(mod_multiple + word_shift, mod);
 	}
 
 	for (index = 1; shift >= 0; --shift) {
@@ -364,101 +480,97 @@ void uECC_vli_mmod(uECC_word_t *result, uECC_word_t *product,
 		}
 		/* Swap the index if there was no borrow */
 		index = !(index ^ borrow);
-		uECC_vli_rshift1(mod_multiple, num_words);
+		uECC_vli_rshift1(mod_multiple);
 		mod_multiple[num_words - 1] |= mod_multiple[num_words] <<
 					       (uECC_WORD_BITS - 1);
-		uECC_vli_rshift1(mod_multiple + num_words, num_words);
+		uECC_vli_rshift1(mod_multiple + num_words);
 	}
-	uECC_vli_set(result, v[index], num_words);
+	uECC_vli_set(result, v[index]);
 }
 
 void uECC_vli_modMult(uECC_word_t *result, const uECC_word_t *left,
-		      const uECC_word_t *right, const uECC_word_t *mod,
-		      wordcount_t num_words)
+		      const uECC_word_t *right, const uECC_word_t *mod)
 {
 	uECC_word_t product[2 * NUM_ECC_WORDS];
-	uECC_vli_mult(product, left, right, num_words);
-	uECC_vli_mmod(result, product, mod, num_words);
+	uECC_vli_mult_rnd(product, left, right, NULL);
+	uECC_vli_mmod(result, product, mod);
+}
+
+static void uECC_vli_modMult_rnd(uECC_word_t *result, const uECC_word_t *left,
+				 const uECC_word_t *right, ecc_wait_state_t *s)
+{
+	uECC_word_t product[2 * NUM_ECC_WORDS];
+	uECC_vli_mult_rnd(product, left, right, s);
+
+	vli_mmod_fast_secp256r1(result, product);
 }
 
 void uECC_vli_modMult_fast(uECC_word_t *result, const uECC_word_t *left,
-			   const uECC_word_t *right, uECC_Curve curve)
+			   const uECC_word_t *right)
 {
-	uECC_word_t product[2 * NUM_ECC_WORDS];
-	uECC_vli_mult(product, left, right, curve->num_words);
-
-	curve->mmod_fast(result, product);
+	uECC_vli_modMult_rnd(result, left, right, NULL);
 }
 
-static void uECC_vli_modSquare_fast(uECC_word_t *result,
-				    const uECC_word_t *left,
-				    uECC_Curve curve)
-{
-	uECC_vli_modMult_fast(result, left, left, curve);
-}
-
-
 #define EVEN(vli) (!(vli[0] & 1))
 
 static void vli_modInv_update(uECC_word_t *uv,
-			      const uECC_word_t *mod,
-			      wordcount_t num_words)
+			      const uECC_word_t *mod)
 {
 
 	uECC_word_t carry = 0;
 
 	if (!EVEN(uv)) {
-		carry = uECC_vli_add(uv, uv, mod, num_words);
+		carry = uECC_vli_add(uv, uv, mod);
 	}
-	uECC_vli_rshift1(uv, num_words);
+	uECC_vli_rshift1(uv);
 	if (carry) {
-		uv[num_words - 1] |= HIGH_BIT_SET;
+		uv[NUM_ECC_WORDS - 1] |= HIGH_BIT_SET;
 	}
 }
 
 void uECC_vli_modInv(uECC_word_t *result, const uECC_word_t *input,
-		     const uECC_word_t *mod, wordcount_t num_words)
+		     const uECC_word_t *mod)
 {
 	uECC_word_t a[NUM_ECC_WORDS], b[NUM_ECC_WORDS];
 	uECC_word_t u[NUM_ECC_WORDS], v[NUM_ECC_WORDS];
 	cmpresult_t cmpResult;
 
-	if (uECC_vli_isZero(input, num_words)) {
-		uECC_vli_clear(result, num_words);
+	if (uECC_vli_isZero(input)) {
+		uECC_vli_clear(result);
 		return;
 	}
 
-	uECC_vli_set(a, input, num_words);
-	uECC_vli_set(b, mod, num_words);
-	uECC_vli_clear(u, num_words);
+	uECC_vli_set(a, input);
+	uECC_vli_set(b, mod);
+	uECC_vli_clear(u);
 	u[0] = 1;
-	uECC_vli_clear(v, num_words);
-	while ((cmpResult = uECC_vli_cmp_unsafe(a, b, num_words)) != 0) {
+	uECC_vli_clear(v);
+	while ((cmpResult = uECC_vli_cmp_unsafe(a, b)) != 0) {
 		if (EVEN(a)) {
-			uECC_vli_rshift1(a, num_words);
-      			vli_modInv_update(u, mod, num_words);
+			uECC_vli_rshift1(a);
+      			vli_modInv_update(u, mod);
     		} else if (EVEN(b)) {
-			uECC_vli_rshift1(b, num_words);
-			vli_modInv_update(v, mod, num_words);
+			uECC_vli_rshift1(b);
+			vli_modInv_update(v, mod);
 		} else if (cmpResult > 0) {
-			uECC_vli_sub(a, a, b, num_words);
-			uECC_vli_rshift1(a, num_words);
-			if (uECC_vli_cmp_unsafe(u, v, num_words) < 0) {
-        			uECC_vli_add(u, u, mod, num_words);
+			uECC_vli_sub(a, a, b);
+			uECC_vli_rshift1(a);
+			if (uECC_vli_cmp_unsafe(u, v) < 0) {
+        			uECC_vli_add(u, u, mod);
       			}
-      			uECC_vli_sub(u, u, v, num_words);
-      			vli_modInv_update(u, mod, num_words);
+      			uECC_vli_sub(u, u, v);
+      			vli_modInv_update(u, mod);
     		} else {
-      			uECC_vli_sub(b, b, a, num_words);
-      			uECC_vli_rshift1(b, num_words);
-      			if (uECC_vli_cmp_unsafe(v, u, num_words) < 0) {
-        			uECC_vli_add(v, v, mod, num_words);
+      			uECC_vli_sub(b, b, a);
+      			uECC_vli_rshift1(b);
+      			if (uECC_vli_cmp_unsafe(v, u) < 0) {
+        			uECC_vli_add(v, v, mod);
       			}
-      			uECC_vli_sub(v, v, u, num_words);
-      			vli_modInv_update(v, mod, num_words);
+      			uECC_vli_sub(v, v, u);
+      			vli_modInv_update(v, mod);
     		}
   	}
-  	uECC_vli_set(result, u, num_words);
+  	uECC_vli_set(result, u);
 }
 
 /* ------ Point operations ------ */
@@ -471,43 +583,43 @@ void double_jacobian_default(uECC_word_t * X1, uECC_word_t * Y1,
 	uECC_word_t t5[NUM_ECC_WORDS];
 	wordcount_t num_words = curve->num_words;
 
-	if (uECC_vli_isZero(Z1, num_words)) {
+	if (uECC_vli_isZero(Z1)) {
 		return;
 	}
 
-	uECC_vli_modSquare_fast(t4, Y1, curve);   /* t4 = y1^2 */
-	uECC_vli_modMult_fast(t5, X1, t4, curve); /* t5 = x1*y1^2 = A */
-	uECC_vli_modSquare_fast(t4, t4, curve);   /* t4 = y1^4 */
-	uECC_vli_modMult_fast(Y1, Y1, Z1, curve); /* t2 = y1*z1 = z3 */
-	uECC_vli_modSquare_fast(Z1, Z1, curve);   /* t3 = z1^2 */
+	uECC_vli_modMult_fast(t4, Y1, Y1);   /* t4 = y1^2 */
+	uECC_vli_modMult_fast(t5, X1, t4); /* t5 = x1*y1^2 = A */
+	uECC_vli_modMult_fast(t4, t4, t4);   /* t4 = y1^4 */
+	uECC_vli_modMult_fast(Y1, Y1, Z1); /* t2 = y1*z1 = z3 */
+	uECC_vli_modMult_fast(Z1, Z1, Z1);   /* t3 = z1^2 */
 
-	uECC_vli_modAdd(X1, X1, Z1, curve->p, num_words); /* t1 = x1 + z1^2 */
-	uECC_vli_modAdd(Z1, Z1, Z1, curve->p, num_words); /* t3 = 2*z1^2 */
-	uECC_vli_modSub(Z1, X1, Z1, curve->p, num_words); /* t3 = x1 - z1^2 */
-	uECC_vli_modMult_fast(X1, X1, Z1, curve); /* t1 = x1^2 - z1^4 */
+	uECC_vli_modAdd(X1, X1, Z1, curve->p); /* t1 = x1 + z1^2 */
+	uECC_vli_modAdd(Z1, Z1, Z1, curve->p); /* t3 = 2*z1^2 */
+	uECC_vli_modSub(Z1, X1, Z1, curve->p); /* t3 = x1 - z1^2 */
+	uECC_vli_modMult_fast(X1, X1, Z1); /* t1 = x1^2 - z1^4 */
 
-	uECC_vli_modAdd(Z1, X1, X1, curve->p, num_words); /* t3 = 2*(x1^2 - z1^4) */
-	uECC_vli_modAdd(X1, X1, Z1, curve->p, num_words); /* t1 = 3*(x1^2 - z1^4) */
+	uECC_vli_modAdd(Z1, X1, X1, curve->p); /* t3 = 2*(x1^2 - z1^4) */
+	uECC_vli_modAdd(X1, X1, Z1, curve->p); /* t1 = 3*(x1^2 - z1^4) */
 	if (uECC_vli_testBit(X1, 0)) {
-		uECC_word_t l_carry = uECC_vli_add(X1, X1, curve->p, num_words);
-		uECC_vli_rshift1(X1, num_words);
+		uECC_word_t l_carry = uECC_vli_add(X1, X1, curve->p);
+		uECC_vli_rshift1(X1);
 		X1[num_words - 1] |= l_carry << (uECC_WORD_BITS - 1);
 	} else {
-		uECC_vli_rshift1(X1, num_words);
+		uECC_vli_rshift1(X1);
 	}
 
 	/* t1 = 3/2*(x1^2 - z1^4) = B */
-	uECC_vli_modSquare_fast(Z1, X1, curve); /* t3 = B^2 */
-	uECC_vli_modSub(Z1, Z1, t5, curve->p, num_words); /* t3 = B^2 - A */
-	uECC_vli_modSub(Z1, Z1, t5, curve->p, num_words); /* t3 = B^2 - 2A = x3 */
-	uECC_vli_modSub(t5, t5, Z1, curve->p, num_words); /* t5 = A - x3 */
-	uECC_vli_modMult_fast(X1, X1, t5, curve); /* t1 = B * (A - x3) */
+	uECC_vli_modMult_fast(Z1, X1, X1); /* t3 = B^2 */
+	uECC_vli_modSub(Z1, Z1, t5, curve->p); /* t3 = B^2 - A */
+	uECC_vli_modSub(Z1, Z1, t5, curve->p); /* t3 = B^2 - 2A = x3 */
+	uECC_vli_modSub(t5, t5, Z1, curve->p); /* t5 = A - x3 */
+	uECC_vli_modMult_fast(X1, X1, t5); /* t1 = B * (A - x3) */
 	/* t4 = B * (A - x3) - y1^4 = y3: */
-	uECC_vli_modSub(t4, X1, t4, curve->p, num_words);
+	uECC_vli_modSub(t4, X1, t4, curve->p);
 
-	uECC_vli_set(X1, Z1, num_words);
-	uECC_vli_set(Z1, Y1, num_words);
-	uECC_vli_set(Y1, t4, num_words);
+	uECC_vli_set(X1, Z1);
+	uECC_vli_set(Z1, Y1);
+	uECC_vli_set(Y1, t4);
 }
 
 void x_side_default(uECC_word_t *result,
@@ -515,13 +627,12 @@ void x_side_default(uECC_word_t *result,
 		    uECC_Curve curve)
 {
 	uECC_word_t _3[NUM_ECC_WORDS] = {3}; /* -a = 3 */
-	wordcount_t num_words = curve->num_words;
 
-	uECC_vli_modSquare_fast(result, x, curve); /* r = x^2 */
-	uECC_vli_modSub(result, result, _3, curve->p, num_words); /* r = x^2 - 3 */
-	uECC_vli_modMult_fast(result, result, x, curve); /* r = x^3 - 3x */
+	uECC_vli_modMult_fast(result, x, x); /* r = x^2 */
+	uECC_vli_modSub(result, result, _3, curve->p); /* r = x^2 - 3 */
+	uECC_vli_modMult_fast(result, result, x); /* r = x^3 - 3x */
 	/* r = x^3 - 3x + b: */
-	uECC_vli_modAdd(result, result, curve->b, curve->p, num_words);
+	uECC_vli_modAdd(result, result, curve->b, curve->p);
 }
 
 uECC_Curve uECC_secp256r1(void)
@@ -535,7 +646,7 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	int carry;
 
 	/* t */
-	uECC_vli_set(result, product, NUM_ECC_WORDS);
+	uECC_vli_set(result, product);
 
 	/* s1 */
 	tmp[0] = tmp[1] = tmp[2] = 0;
@@ -544,8 +655,8 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	tmp[5] = product[13];
 	tmp[6] = product[14];
 	tmp[7] = product[15];
-	carry = uECC_vli_add(tmp, tmp, tmp, NUM_ECC_WORDS);
-	carry += uECC_vli_add(result, result, tmp, NUM_ECC_WORDS);
+	carry = uECC_vli_add(tmp, tmp, tmp);
+	carry += uECC_vli_add(result, result, tmp);
 
 	/* s2 */
 	tmp[3] = product[12];
@@ -553,8 +664,8 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	tmp[5] = product[14];
 	tmp[6] = product[15];
 	tmp[7] = 0;
-	carry += uECC_vli_add(tmp, tmp, tmp, NUM_ECC_WORDS);
-	carry += uECC_vli_add(result, result, tmp, NUM_ECC_WORDS);
+	carry += uECC_vli_add(tmp, tmp, tmp);
+	carry += uECC_vli_add(result, result, tmp);
 
 	/* s3 */
 	tmp[0] = product[8];
@@ -563,7 +674,7 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	tmp[3] = tmp[4] = tmp[5] = 0;
 	tmp[6] = product[14];
 	tmp[7] = product[15];
-  	carry += uECC_vli_add(result, result, tmp, NUM_ECC_WORDS);
+  	carry += uECC_vli_add(result, result, tmp);
 
 	/* s4 */
 	tmp[0] = product[9];
@@ -574,7 +685,7 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	tmp[5] = product[15];
 	tmp[6] = product[13];
 	tmp[7] = product[8];
-	carry += uECC_vli_add(result, result, tmp, NUM_ECC_WORDS);
+	carry += uECC_vli_add(result, result, tmp);
 
 	/* d1 */
 	tmp[0] = product[11];
@@ -583,7 +694,7 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	tmp[3] = tmp[4] = tmp[5] = 0;
 	tmp[6] = product[8];
 	tmp[7] = product[10];
-	carry -= uECC_vli_sub(result, result, tmp, NUM_ECC_WORDS);
+	carry -= uECC_vli_sub(result, result, tmp);
 
 	/* d2 */
 	tmp[0] = product[12];
@@ -593,7 +704,7 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	tmp[4] = tmp[5] = 0;
 	tmp[6] = product[9];
 	tmp[7] = product[11];
-	carry -= uECC_vli_sub(result, result, tmp, NUM_ECC_WORDS);
+	carry -= uECC_vli_sub(result, result, tmp);
 
 	/* d3 */
 	tmp[0] = product[13];
@@ -604,7 +715,7 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	tmp[5] = product[10];
 	tmp[6] = 0;
 	tmp[7] = product[12];
-	carry -= uECC_vli_sub(result, result, tmp, NUM_ECC_WORDS);
+	carry -= uECC_vli_sub(result, result, tmp);
 
 	/* d4 */
 	tmp[0] = product[14];
@@ -615,35 +726,35 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 	tmp[5] = product[11];
 	tmp[6] = 0;
 	tmp[7] = product[13];
-	carry -= uECC_vli_sub(result, result, tmp, NUM_ECC_WORDS);
+	carry -= uECC_vli_sub(result, result, tmp);
 
 	if (carry < 0) {
 		do {
-			carry += uECC_vli_add(result, result, curve_secp256r1.p, NUM_ECC_WORDS);
+			carry += uECC_vli_add(result, result, curve_secp256r1.p);
 		}
 		while (carry < 0);
 	} else  {
 		while (carry || 
-		       uECC_vli_cmp_unsafe(curve_secp256r1.p, result, NUM_ECC_WORDS) != 1) {
-			carry -= uECC_vli_sub(result, result, curve_secp256r1.p, NUM_ECC_WORDS);
+		       uECC_vli_cmp_unsafe(curve_secp256r1.p, result) != 1) {
+			carry -= uECC_vli_sub(result, result, curve_secp256r1.p);
 		}
 	}
 }
 
 uECC_word_t EccPoint_isZero(const uECC_word_t *point, uECC_Curve curve)
 {
-	return uECC_vli_isZero(point, curve->num_words * 2);
+	(void) curve;
+	return uECC_vli_isZero(point);
 }
 
-void apply_z(uECC_word_t * X1, uECC_word_t * Y1, const uECC_word_t * const Z,
-	     uECC_Curve curve)
+void apply_z(uECC_word_t * X1, uECC_word_t * Y1, const uECC_word_t * const Z)
 {
 	uECC_word_t t1[NUM_ECC_WORDS];
 
-	uECC_vli_modSquare_fast(t1, Z, curve);    /* z^2 */
-	uECC_vli_modMult_fast(X1, X1, t1, curve); /* x1 * z^2 */
-	uECC_vli_modMult_fast(t1, t1, Z, curve);  /* z^3 */
-	uECC_vli_modMult_fast(Y1, Y1, t1, curve); /* y1 * z^3 */
+	uECC_vli_modMult_fast(t1, Z, Z);    /* z^2 */
+	uECC_vli_modMult_fast(X1, X1, t1); /* x1 * z^2 */
+	uECC_vli_modMult_fast(t1, t1, Z);  /* z^3 */
+	uECC_vli_modMult_fast(Y1, Y1, t1); /* y1 * z^3 */
 }
 
 /* P = (x1, y1) => 2P, (x2, y2) => P' */
@@ -653,94 +764,100 @@ static void XYcZ_initial_double(uECC_word_t * X1, uECC_word_t * Y1,
 				uECC_Curve curve)
 {
 	uECC_word_t z[NUM_ECC_WORDS];
-	wordcount_t num_words = curve->num_words;
 	if (initial_Z) {
-		uECC_vli_set(z, initial_Z, num_words);
+		uECC_vli_set(z, initial_Z);
 	} else {
-		uECC_vli_clear(z, num_words);
+		uECC_vli_clear(z);
 		z[0] = 1;
 	}
 
-	uECC_vli_set(X2, X1, num_words);
-	uECC_vli_set(Y2, Y1, num_words);
+	uECC_vli_set(X2, X1);
+	uECC_vli_set(Y2, Y1);
 
-	apply_z(X1, Y1, z, curve);
+	apply_z(X1, Y1, z);
 	curve->double_jacobian(X1, Y1, z, curve);
-	apply_z(X2, Y2, z, curve);
+	apply_z(X2, Y2, z);
+}
+
+static void XYcZ_add_rnd(uECC_word_t * X1, uECC_word_t * Y1,
+			 uECC_word_t * X2, uECC_word_t * Y2,
+			 ecc_wait_state_t *s)
+{
+	/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
+	uECC_word_t t5[NUM_ECC_WORDS];
+	const uECC_Curve curve = &curve_secp256r1;
+
+	uECC_vli_modSub(t5, X2, X1, curve->p); /* t5 = x2 - x1 */
+	uECC_vli_modMult_rnd(t5, t5, t5, s); /* t5 = (x2 - x1)^2 = A */
+	uECC_vli_modMult_rnd(X1, X1, t5, s); /* t1 = x1*A = B */
+	uECC_vli_modMult_rnd(X2, X2, t5, s); /* t3 = x2*A = C */
+	uECC_vli_modSub(Y2, Y2, Y1, curve->p); /* t4 = y2 - y1 */
+	uECC_vli_modMult_rnd(t5, Y2, Y2, s); /* t5 = (y2 - y1)^2 = D */
+
+	uECC_vli_modSub(t5, t5, X1, curve->p); /* t5 = D - B */
+	uECC_vli_modSub(t5, t5, X2, curve->p); /* t5 = D - B - C = x3 */
+	uECC_vli_modSub(X2, X2, X1, curve->p); /* t3 = C - B */
+	uECC_vli_modMult_rnd(Y1, Y1, X2, s); /* t2 = y1*(C - B) */
+	uECC_vli_modSub(X2, X1, t5, curve->p); /* t3 = B - x3 */
+	uECC_vli_modMult_rnd(Y2, Y2, X2, s); /* t4 = (y2 - y1)*(B - x3) */
+	uECC_vli_modSub(Y2, Y2, Y1, curve->p); /* t4 = y3 */
+
+	uECC_vli_set(X2, t5);
 }
 
 void XYcZ_add(uECC_word_t * X1, uECC_word_t * Y1,
 	      uECC_word_t * X2, uECC_word_t * Y2,
 	      uECC_Curve curve)
 {
-	/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
-	uECC_word_t t5[NUM_ECC_WORDS];
-	wordcount_t num_words = curve->num_words;
-
-	uECC_vli_modSub(t5, X2, X1, curve->p, num_words); /* t5 = x2 - x1 */
-	uECC_vli_modSquare_fast(t5, t5, curve); /* t5 = (x2 - x1)^2 = A */
-	uECC_vli_modMult_fast(X1, X1, t5, curve); /* t1 = x1*A = B */
-	uECC_vli_modMult_fast(X2, X2, t5, curve); /* t3 = x2*A = C */
-	uECC_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y2 - y1 */
-	uECC_vli_modSquare_fast(t5, Y2, curve); /* t5 = (y2 - y1)^2 = D */
-
-	uECC_vli_modSub(t5, t5, X1, curve->p, num_words); /* t5 = D - B */
-	uECC_vli_modSub(t5, t5, X2, curve->p, num_words); /* t5 = D - B - C = x3 */
-	uECC_vli_modSub(X2, X2, X1, curve->p, num_words); /* t3 = C - B */
-	uECC_vli_modMult_fast(Y1, Y1, X2, curve); /* t2 = y1*(C - B) */
-	uECC_vli_modSub(X2, X1, t5, curve->p, num_words); /* t3 = B - x3 */
-	uECC_vli_modMult_fast(Y2, Y2, X2, curve); /* t4 = (y2 - y1)*(B - x3) */
-	uECC_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y3 */
-
-	uECC_vli_set(X2, t5, num_words);
+	(void) curve;
+	XYcZ_add_rnd(X1, Y1, X2, Y2, NULL);
 }
 
 /* Input P = (x1, y1, Z), Q = (x2, y2, Z)
    Output P + Q = (x3, y3, Z3), P - Q = (x3', y3', Z3)
    or P => P - Q, Q => P + Q
  */
-static void XYcZ_addC(uECC_word_t * X1, uECC_word_t * Y1,
-		      uECC_word_t * X2, uECC_word_t * Y2,
-		      uECC_Curve curve)
+static void XYcZ_addC_rnd(uECC_word_t * X1, uECC_word_t * Y1,
+			  uECC_word_t * X2, uECC_word_t * Y2,
+			  ecc_wait_state_t *s)
 {
 	/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
 	uECC_word_t t5[NUM_ECC_WORDS];
 	uECC_word_t t6[NUM_ECC_WORDS];
 	uECC_word_t t7[NUM_ECC_WORDS];
-	wordcount_t num_words = curve->num_words;
+	const uECC_Curve curve = &curve_secp256r1;
 
-	uECC_vli_modSub(t5, X2, X1, curve->p, num_words); /* t5 = x2 - x1 */
-	uECC_vli_modSquare_fast(t5, t5, curve); /* t5 = (x2 - x1)^2 = A */
-	uECC_vli_modMult_fast(X1, X1, t5, curve); /* t1 = x1*A = B */
-	uECC_vli_modMult_fast(X2, X2, t5, curve); /* t3 = x2*A = C */
-	uECC_vli_modAdd(t5, Y2, Y1, curve->p, num_words); /* t5 = y2 + y1 */
-	uECC_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y2 - y1 */
+	uECC_vli_modSub(t5, X2, X1, curve->p); /* t5 = x2 - x1 */
+	uECC_vli_modMult_rnd(t5, t5, t5, s); /* t5 = (x2 - x1)^2 = A */
+	uECC_vli_modMult_rnd(X1, X1, t5, s); /* t1 = x1*A = B */
+	uECC_vli_modMult_rnd(X2, X2, t5, s); /* t3 = x2*A = C */
+	uECC_vli_modAdd(t5, Y2, Y1, curve->p); /* t5 = y2 + y1 */
+	uECC_vli_modSub(Y2, Y2, Y1, curve->p); /* t4 = y2 - y1 */
 
-	uECC_vli_modSub(t6, X2, X1, curve->p, num_words); /* t6 = C - B */
-	uECC_vli_modMult_fast(Y1, Y1, t6, curve); /* t2 = y1 * (C - B) = E */
-	uECC_vli_modAdd(t6, X1, X2, curve->p, num_words); /* t6 = B + C */
-	uECC_vli_modSquare_fast(X2, Y2, curve); /* t3 = (y2 - y1)^2 = D */
-	uECC_vli_modSub(X2, X2, t6, curve->p, num_words); /* t3 = D - (B + C) = x3 */
+	uECC_vli_modSub(t6, X2, X1, curve->p); /* t6 = C - B */
+	uECC_vli_modMult_rnd(Y1, Y1, t6, s); /* t2 = y1 * (C - B) = E */
+	uECC_vli_modAdd(t6, X1, X2, curve->p); /* t6 = B + C */
+	uECC_vli_modMult_rnd(X2, Y2, Y2, s); /* t3 = (y2 - y1)^2 = D */
+	uECC_vli_modSub(X2, X2, t6, curve->p); /* t3 = D - (B + C) = x3 */
 
-	uECC_vli_modSub(t7, X1, X2, curve->p, num_words); /* t7 = B - x3 */
-	uECC_vli_modMult_fast(Y2, Y2, t7, curve); /* t4 = (y2 - y1)*(B - x3) */
+	uECC_vli_modSub(t7, X1, X2, curve->p); /* t7 = B - x3 */
+	uECC_vli_modMult_rnd(Y2, Y2, t7, s); /* t4 = (y2 - y1)*(B - x3) */
 	/* t4 = (y2 - y1)*(B - x3) - E = y3: */
-	uECC_vli_modSub(Y2, Y2, Y1, curve->p, num_words);
+	uECC_vli_modSub(Y2, Y2, Y1, curve->p);
 
-	uECC_vli_modSquare_fast(t7, t5, curve); /* t7 = (y2 + y1)^2 = F */
-	uECC_vli_modSub(t7, t7, t6, curve->p, num_words); /* t7 = F - (B + C) = x3' */
-	uECC_vli_modSub(t6, t7, X1, curve->p, num_words); /* t6 = x3' - B */
-	uECC_vli_modMult_fast(t6, t6, t5, curve); /* t6 = (y2+y1)*(x3' - B) */
+	uECC_vli_modMult_rnd(t7, t5, t5, s); /* t7 = (y2 + y1)^2 = F */
+	uECC_vli_modSub(t7, t7, t6, curve->p); /* t7 = F - (B + C) = x3' */
+	uECC_vli_modSub(t6, t7, X1, curve->p); /* t6 = x3' - B */
+	uECC_vli_modMult_rnd(t6, t6, t5, s); /* t6 = (y2+y1)*(x3' - B) */
 	/* t2 = (y2+y1)*(x3' - B) - E = y3': */
-	uECC_vli_modSub(Y1, t6, Y1, curve->p, num_words);
+	uECC_vli_modSub(Y1, t6, Y1, curve->p);
 
-	uECC_vli_set(X1, t7, num_words);
+	uECC_vli_set(X1, t7);
 }
 
-void EccPoint_mult(uECC_word_t * result, const uECC_word_t * point,
+static void EccPoint_mult(uECC_word_t * result, const uECC_word_t * point,
 		   const uECC_word_t * scalar,
-		   const uECC_word_t * initial_Z,
-		   bitcount_t num_bits, uECC_Curve curve) 
+		   const uECC_word_t * initial_Z)
 {
 	/* R0 and R1 */
 	uECC_word_t Rx[2][NUM_ECC_WORDS];
@@ -748,57 +865,103 @@ void EccPoint_mult(uECC_word_t * result, const uECC_word_t * point,
 	uECC_word_t z[NUM_ECC_WORDS];
 	bitcount_t i;
 	uECC_word_t nb;
-	wordcount_t num_words = curve->num_words;
+	const wordcount_t num_words = NUM_ECC_WORDS;
+	const bitcount_t num_bits = NUM_ECC_BITS + 1; /* from regularize_k */
+	const uECC_Curve curve = uECC_secp256r1();
+	ecc_wait_state_t wait_state;
+	ecc_wait_state_t * const ws = g_rng_function ? &wait_state : NULL;
 
-	uECC_vli_set(Rx[1], point, num_words);
-  	uECC_vli_set(Ry[1], point + num_words, num_words);
+	uECC_vli_set(Rx[1], point);
+  	uECC_vli_set(Ry[1], point + num_words);
 
 	XYcZ_initial_double(Rx[1], Ry[1], Rx[0], Ry[0], initial_Z, curve);
 
 	for (i = num_bits - 2; i > 0; --i) {
+		ecc_wait_state_reset(ws);
 		nb = !uECC_vli_testBit(scalar, i);
-		XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);
-		XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
+		XYcZ_addC_rnd(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], ws);
+		XYcZ_add_rnd(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], ws);
 	}
 
+	ecc_wait_state_reset(ws);
 	nb = !uECC_vli_testBit(scalar, 0);
-	XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);
+	XYcZ_addC_rnd(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], ws);
 
 	/* Find final 1/Z value. */
-	uECC_vli_modSub(z, Rx[1], Rx[0], curve->p, num_words); /* X1 - X0 */
-	uECC_vli_modMult_fast(z, z, Ry[1 - nb], curve); /* Yb * (X1 - X0) */
-	uECC_vli_modMult_fast(z, z, point, curve); /* xP * Yb * (X1 - X0) */
-	uECC_vli_modInv(z, z, curve->p, num_words); /* 1 / (xP * Yb * (X1 - X0))*/
+	uECC_vli_modSub(z, Rx[1], Rx[0], curve->p); /* X1 - X0 */
+	uECC_vli_modMult_fast(z, z, Ry[1 - nb]); /* Yb * (X1 - X0) */
+	uECC_vli_modMult_fast(z, z, point); /* xP * Yb * (X1 - X0) */
+	uECC_vli_modInv(z, z, curve->p); /* 1 / (xP * Yb * (X1 - X0))*/
 	/* yP / (xP * Yb * (X1 - X0)) */
-	uECC_vli_modMult_fast(z, z, point + num_words, curve);
+	uECC_vli_modMult_fast(z, z, point + num_words);
 	/* Xb * yP / (xP * Yb * (X1 - X0)) */
-	uECC_vli_modMult_fast(z, z, Rx[1 - nb], curve);
+	uECC_vli_modMult_fast(z, z, Rx[1 - nb]);
 	/* End 1/Z calculation */
 
-	XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
-	apply_z(Rx[0], Ry[0], z, curve);
+	XYcZ_add_rnd(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], ws);
+	apply_z(Rx[0], Ry[0], z);
 
-	uECC_vli_set(result, Rx[0], num_words);
-	uECC_vli_set(result + num_words, Ry[0], num_words);
+	uECC_vli_set(result, Rx[0]);
+	uECC_vli_set(result + num_words, Ry[0]);
 }
 
-uECC_word_t regularize_k(const uECC_word_t * const k, uECC_word_t *k0,
-			 uECC_word_t *k1, uECC_Curve curve)
+static uECC_word_t regularize_k(const uECC_word_t * const k, uECC_word_t *k0,
+			 uECC_word_t *k1)
 {
 
-	wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
+	wordcount_t num_n_words = NUM_ECC_WORDS;
+	bitcount_t num_n_bits = NUM_ECC_BITS;
+	const uECC_Curve curve = uECC_secp256r1();
 
-	bitcount_t num_n_bits = curve->num_n_bits;
-
-	uECC_word_t carry = uECC_vli_add(k0, k, curve->n, num_n_words) ||
+	uECC_word_t carry = uECC_vli_add(k0, k, curve->n) ||
 			     (num_n_bits < ((bitcount_t)num_n_words * uECC_WORD_SIZE * 8) &&
 			     uECC_vli_testBit(k0, num_n_bits));
 
-	uECC_vli_add(k1, k0, curve->n, num_n_words);
+	uECC_vli_add(k1, k0, curve->n);
 
 	return carry;
 }
 
+int EccPoint_mult_safer(uECC_word_t * result, const uECC_word_t * point,
+			const uECC_word_t * scalar, uECC_Curve curve)
+{
+	uECC_word_t tmp[NUM_ECC_WORDS];
+	uECC_word_t s[NUM_ECC_WORDS];
+	uECC_word_t *k2[2] = {tmp, s};
+	wordcount_t num_words = NUM_ECC_WORDS;
+	uECC_word_t carry;
+	uECC_word_t *initial_Z = 0;
+	int r;
+
+	if (curve != uECC_secp256r1())
+		return 0;
+
+	/* Regularize the bitcount for the private key so that attackers cannot use a
+	 * side channel attack to learn the number of leading zeros. */
+	carry = regularize_k(scalar, tmp, s);
+
+	/* If an RNG function was specified, get a random initial Z value to
+         * protect against side-channel attacks such as Template SPA */
+	if (g_rng_function) {
+		if (!uECC_generate_random_int(k2[carry], curve->p, num_words)) {
+			r = 0;
+			goto clear_and_out;
+		}
+		initial_Z = k2[carry];
+	}
+
+	EccPoint_mult(result, point, k2[!carry], initial_Z);
+	r = 1;
+
+clear_and_out:
+	/* erasing temporary buffer used to store secret: */
+	mbedtls_platform_zeroize(k2, sizeof(k2));
+	mbedtls_platform_zeroize(tmp, sizeof(tmp));
+	mbedtls_platform_zeroize(s, sizeof(s));
+
+	return r;
+}
+
 uECC_word_t EccPoint_compute_public_key(uECC_word_t *result,
 					uECC_word_t *private_key,
 					uECC_Curve curve)
@@ -809,11 +972,14 @@ uECC_word_t EccPoint_compute_public_key(uECC_word_t *result,
 	uECC_word_t *p2[2] = {tmp1, tmp2};
 	uECC_word_t carry;
 
+	if (curve != uECC_secp256r1())
+		return 0;
+
 	/* Regularize the bitcount for the private key so that attackers cannot
 	 * use a side channel attack to learn the number of leading zeros. */
-	carry = regularize_k(private_key, tmp1, tmp2, curve);
+	carry = regularize_k(private_key, tmp1, tmp2);
 
-	EccPoint_mult(result, curve->G, p2[!carry], 0, curve->num_n_bits + 1, curve);
+	EccPoint_mult(result, curve->G, p2[!carry], 0);
 
 	if (EccPoint_isZero(result, curve)) {
 		return 0;
@@ -837,7 +1003,7 @@ void uECC_vli_bytesToNative(unsigned int *native, const uint8_t *bytes,
 			    int num_bytes)
 {
 	wordcount_t i;
-	uECC_vli_clear(native, (num_bytes + (uECC_WORD_SIZE - 1)) / uECC_WORD_SIZE);
+	uECC_vli_clear(native);
 	for (i = 0; i < num_bytes; ++i) {
 		unsigned b = num_bytes - 1 - i;
 		native[b / uECC_WORD_SIZE] |=
@@ -850,7 +1016,7 @@ int uECC_generate_random_int(uECC_word_t *random, const uECC_word_t *top,
 {
 	uECC_word_t mask = (uECC_word_t)-1;
 	uECC_word_t tries;
-	bitcount_t num_bits = uECC_vli_numBits(top, num_words);
+	bitcount_t num_bits = uECC_vli_numBits(top);
 
 	if (!g_rng_function) {
 		return 0;
@@ -862,8 +1028,8 @@ int uECC_generate_random_int(uECC_word_t *random, const uECC_word_t *top,
     		}
 		random[num_words - 1] &=
         		mask >> ((bitcount_t)(num_words * uECC_WORD_SIZE * 8 - num_bits));
-		if (!uECC_vli_isZero(random, num_words) &&
-			uECC_vli_cmp(top, random, num_words) == 1) {
+		if (!uECC_vli_isZero(random) &&
+			uECC_vli_cmp(top, random) == 1) {
 			return 1;
 		}
 	}
@@ -883,16 +1049,16 @@ int uECC_valid_point(const uECC_word_t *point, uECC_Curve curve)
 	}
 
 	/* x and y must be smaller than p. */
-	if (uECC_vli_cmp_unsafe(curve->p, point, num_words) != 1 ||
-		uECC_vli_cmp_unsafe(curve->p, point + num_words, num_words) != 1) {
+	if (uECC_vli_cmp_unsafe(curve->p, point) != 1 ||
+		uECC_vli_cmp_unsafe(curve->p, point + num_words) != 1) {
 		return -2;
 	}
 
-	uECC_vli_modSquare_fast(tmp1, point + num_words, curve);
+	uECC_vli_modMult_fast(tmp1, point + num_words, point + num_words);
 	curve->x_side(tmp2, point, curve); /* tmp2 = x^3 + ax + b */
 
 	/* Make sure that y^2 == x^3 + ax + b */
-	if (uECC_vli_equal(tmp1, tmp2, num_words) != 0)
+	if (uECC_vli_equal(tmp1, tmp2) != 0)
 		return -3;
 
 	return 0;
@@ -909,7 +1075,7 @@ int uECC_valid_public_key(const uint8_t *public_key, uECC_Curve curve)
 	public_key + curve->num_bytes,
 	curve->num_bytes);
 
-	if (uECC_vli_cmp_unsafe(_public, curve->G, NUM_ECC_WORDS * 2) == 0) {
+	if (memcmp(_public, curve->G, NUM_ECC_WORDS * 2) == 0) {
 		return -4;
 	}
 
@@ -929,11 +1095,11 @@ int uECC_compute_public_key(const uint8_t *private_key, uint8_t *public_key,
 	BITS_TO_BYTES(curve->num_n_bits));
 
 	/* Make sure the private key is in the range [1, n-1]. */
-	if (uECC_vli_isZero(_private, BITS_TO_WORDS(curve->num_n_bits))) {
+	if (uECC_vli_isZero(_private)) {
 		return 0;
 	}
 
-	if (uECC_vli_cmp(curve->n, _private, BITS_TO_WORDS(curve->num_n_bits)) != 1) {
+	if (uECC_vli_cmp(curve->n, _private) != 1) {
 		return 0;
 	}
 
diff --git a/tinycrypt/ecc_dh.c b/tinycrypt/ecc_dh.c
index 54b9a8ab4..71c51f5a8 100644
--- a/tinycrypt/ecc_dh.c
+++ b/tinycrypt/ecc_dh.c
@@ -72,12 +72,6 @@
 #include <string.h>
 #include "mbedtls/platform_util.h"
 
-#if default_RNG_defined
-static uECC_RNG_Function g_rng_function = &default_CSPRNG;
-#else
-static uECC_RNG_Function g_rng_function = 0;
-#endif
-
 int uECC_make_key_with_d(uint8_t *public_key, uint8_t *private_key,
 			 unsigned int *d, uECC_Curve curve)
 {
@@ -129,7 +123,7 @@ int uECC_make_key(uint8_t *public_key, uint8_t *private_key, uECC_Curve curve)
 		}
 
 		/* computing modular reduction of _random (see FIPS 186.4 B.4.1): */
-		uECC_vli_mmod(_private, _random, curve->n, BITS_TO_WORDS(curve->num_n_bits));
+		uECC_vli_mmod(_private, _random, curve->n);
 
 		/* Computing public-key from private: */
 		if (EccPoint_compute_public_key(_public, _private, curve)) {
@@ -160,15 +154,16 @@ int uECC_shared_secret(const uint8_t *public_key, const uint8_t *private_key,
 
 	uECC_word_t _public[NUM_ECC_WORDS * 2];
 	uECC_word_t _private[NUM_ECC_WORDS];
-
-	uECC_word_t tmp[NUM_ECC_WORDS];
-	uECC_word_t *p2[2] = {_private, tmp};
-	uECC_word_t *initial_Z = 0;
-	uECC_word_t carry;
 	wordcount_t num_words = curve->num_words;
 	wordcount_t num_bytes = curve->num_bytes;
 	int r;
 
+        /* Protect against invalid curve attacks */
+        if (uECC_valid_public_key(public_key, curve) != 0) {
+            r = 0;
+            goto clear_and_out;
+        }
+
 	/* Converting buffers to correct bit order: */
 	uECC_vli_bytesToNative(_private,
       			       private_key,
@@ -180,30 +175,15 @@ int uECC_shared_secret(const uint8_t *public_key, const uint8_t *private_key,
 			       public_key + num_bytes,
 			       num_bytes);
 
-	/* Regularize the bitcount for the private key so that attackers cannot use a
-	 * side channel attack to learn the number of leading zeros. */
-	carry = regularize_k(_private, _private, tmp, curve);
-
-	/* If an RNG function was specified, try to get a random initial Z value to
-	 * improve protection against side-channel attacks. */
-	if (g_rng_function) {
-		if (!uECC_generate_random_int(p2[carry], curve->p, num_words)) {
-			r = 0;
-			goto clear_and_out;
-    		}
-    		initial_Z = p2[carry];
-  	}
-
-	EccPoint_mult(_public, _public, p2[!carry], initial_Z, curve->num_n_bits + 1,
-		      curve);
+	r = EccPoint_mult_safer(_public, _public, _private, curve);
+        if (r == 0)
+            goto clear_and_out;
 
 	uECC_vli_nativeToBytes(secret, num_bytes, _public);
 	r = !EccPoint_isZero(_public, curve);
 
 clear_and_out:
 	/* erasing temporary buffer used to store secret: */
-	mbedtls_platform_zeroize(p2, sizeof(p2));
-	mbedtls_platform_zeroize(tmp, sizeof(tmp));
 	mbedtls_platform_zeroize(_private, sizeof(_private));
 
 	return r;
diff --git a/tinycrypt/ecc_dsa.c b/tinycrypt/ecc_dsa.c
index a3893d37f..04b1bfabd 100644
--- a/tinycrypt/ecc_dsa.c
+++ b/tinycrypt/ecc_dsa.c
@@ -87,7 +87,7 @@ static void bits2int(uECC_word_t *native, const uint8_t *bits,
 		bits_size = num_n_bytes;
 	}
 
-	uECC_vli_clear(native, num_n_words);
+	uECC_vli_clear(native);
 	uECC_vli_bytesToNative(native, bits, bits_size);
 	if (bits_size * 8 <= (unsigned)curve->num_n_bits) {
 		return;
@@ -102,8 +102,8 @@ static void bits2int(uECC_word_t *native, const uint8_t *bits,
 	}
 
 	/* Reduce mod curve_n */
-	if (uECC_vli_cmp_unsafe(curve->n, native, num_n_words) != 1) {
-		uECC_vli_sub(native, native, curve->n, num_n_words);
+	if (uECC_vli_cmp_unsafe(curve->n, native) != 1) {
+		uECC_vli_sub(native, native, curve->n);
 	}
 }
 
@@ -114,29 +114,26 @@ int uECC_sign_with_k(const uint8_t *private_key, const uint8_t *message_hash,
 
 	uECC_word_t tmp[NUM_ECC_WORDS];
 	uECC_word_t s[NUM_ECC_WORDS];
-	uECC_word_t *k2[2] = {tmp, s};
 	uECC_word_t p[NUM_ECC_WORDS * 2];
-	uECC_word_t carry;
-	wordcount_t num_words = curve->num_words;
 	wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
-	bitcount_t num_n_bits = curve->num_n_bits;
+	int r;
+
 
 	/* Make sure 0 < k < curve_n */
-  	if (uECC_vli_isZero(k, num_words) ||
-	    uECC_vli_cmp(curve->n, k, num_n_words) != 1) {
+  	if (uECC_vli_isZero(k) ||
+	    uECC_vli_cmp(curve->n, k) != 1) {
 		return 0;
 	}
 
-	carry = regularize_k(k, tmp, s, curve);
-	EccPoint_mult(p, curve->G, k2[!carry], 0, num_n_bits + 1, curve);
-	if (uECC_vli_isZero(p, num_words)) {
+	r = EccPoint_mult_safer(p, curve->G, k, curve);
+	if (r == 0 || uECC_vli_isZero(p)) {
 		return 0;
 	}
 
 	/* If an RNG function was specified, get a random number
 	to prevent side channel analysis of k. */
 	if (!g_rng_function) {
-		uECC_vli_clear(tmp, num_n_words);
+		uECC_vli_clear(tmp);
 		tmp[0] = 1;
 	}
 	else if (!uECC_generate_random_int(tmp, curve->n, num_n_words)) {
@@ -145,9 +142,9 @@ int uECC_sign_with_k(const uint8_t *private_key, const uint8_t *message_hash,
 
 	/* Prevent side channel analysis of uECC_vli_modInv() to determine
 	bits of k / the private key by premultiplying by a random number */
-	uECC_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k' = rand * k */
-	uECC_vli_modInv(k, k, curve->n, num_n_words);       /* k = 1 / k' */
-	uECC_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k = 1 / k */
+	uECC_vli_modMult(k, k, tmp, curve->n); /* k' = rand * k */
+	uECC_vli_modInv(k, k, curve->n);       /* k = 1 / k' */
+	uECC_vli_modMult(k, k, tmp, curve->n); /* k = 1 / k */
 
 	uECC_vli_nativeToBytes(signature, curve->num_bytes, p); /* store r */
 
@@ -155,13 +152,13 @@ int uECC_sign_with_k(const uint8_t *private_key, const uint8_t *message_hash,
 	uECC_vli_bytesToNative(tmp, private_key, BITS_TO_BYTES(curve->num_n_bits));
 
 	s[num_n_words - 1] = 0;
-	uECC_vli_set(s, p, num_words);
-	uECC_vli_modMult(s, tmp, s, curve->n, num_n_words); /* s = r*d */
+	uECC_vli_set(s, p);
+	uECC_vli_modMult(s, tmp, s, curve->n); /* s = r*d */
 
 	bits2int(tmp, message_hash, hash_size, curve);
-	uECC_vli_modAdd(s, tmp, s, curve->n, num_n_words); /* s = e + r*d */
-	uECC_vli_modMult(s, s, k, curve->n, num_n_words);  /* s = (e + r*d) / k */
-	if (uECC_vli_numBits(s, num_n_words) > (bitcount_t)curve->num_bytes * 8) {
+	uECC_vli_modAdd(s, tmp, s, curve->n); /* s = e + r*d */
+	uECC_vli_modMult(s, s, k, curve->n);  /* s = (e + r*d) / k */
+	if (uECC_vli_numBits(s) > (bitcount_t)curve->num_bytes * 8) {
 		return 0;
 	}
 
@@ -185,7 +182,7 @@ int uECC_sign(const uint8_t *private_key, const uint8_t *message_hash,
 		}
 
 		// computing k as modular reduction of _random (see FIPS 186.4 B.5.1):
-		uECC_vli_mmod(k, _random, curve->n, BITS_TO_WORDS(curve->num_n_bits));
+		uECC_vli_mmod(k, _random, curve->n);
 
 		if (uECC_sign_with_k(private_key, message_hash, hash_size, k, signature, 
 		    curve)) {
@@ -223,6 +220,9 @@ int uECC_verify(const uint8_t *public_key, const uint8_t *message_hash,
 	wordcount_t num_words = curve->num_words;
 	wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
 
+	if (curve != uECC_secp256r1())
+		return 0;
+
 	rx[num_n_words - 1] = 0;
 	r[num_n_words - 1] = 0;
 	s[num_n_words - 1] = 0;
@@ -234,46 +234,46 @@ int uECC_verify(const uint8_t *public_key, const uint8_t *message_hash,
 	uECC_vli_bytesToNative(s, signature + curve->num_bytes, curve->num_bytes);
 
 	/* r, s must not be 0. */
-	if (uECC_vli_isZero(r, num_words) || uECC_vli_isZero(s, num_words)) {
+	if (uECC_vli_isZero(r) || uECC_vli_isZero(s)) {
 		return 0;
 	}
 
 	/* r, s must be < n. */
-	if (uECC_vli_cmp_unsafe(curve->n, r, num_n_words) != 1 ||
-	    uECC_vli_cmp_unsafe(curve->n, s, num_n_words) != 1) {
+	if (uECC_vli_cmp_unsafe(curve->n, r) != 1 ||
+	    uECC_vli_cmp_unsafe(curve->n, s) != 1) {
 		return 0;
 	}
 
 	/* Calculate u1 and u2. */
-	uECC_vli_modInv(z, s, curve->n, num_n_words); /* z = 1/s */
+	uECC_vli_modInv(z, s, curve->n); /* z = 1/s */
 	u1[num_n_words - 1] = 0;
 	bits2int(u1, message_hash, hash_size, curve);
-	uECC_vli_modMult(u1, u1, z, curve->n, num_n_words); /* u1 = e/s */
-	uECC_vli_modMult(u2, r, z, curve->n, num_n_words); /* u2 = r/s */
+	uECC_vli_modMult(u1, u1, z, curve->n); /* u1 = e/s */
+	uECC_vli_modMult(u2, r, z, curve->n); /* u2 = r/s */
 
 	/* Calculate sum = G + Q. */
-	uECC_vli_set(sum, _public, num_words);
-	uECC_vli_set(sum + num_words, _public + num_words, num_words);
-	uECC_vli_set(tx, curve->G, num_words);
-	uECC_vli_set(ty, curve->G + num_words, num_words);
-	uECC_vli_modSub(z, sum, tx, curve->p, num_words); /* z = x2 - x1 */
+	uECC_vli_set(sum, _public);
+	uECC_vli_set(sum + num_words, _public + num_words);
+	uECC_vli_set(tx, curve->G);
+	uECC_vli_set(ty, curve->G + num_words);
+	uECC_vli_modSub(z, sum, tx, curve->p); /* z = x2 - x1 */
 	XYcZ_add(tx, ty, sum, sum + num_words, curve);
-	uECC_vli_modInv(z, z, curve->p, num_words); /* z = 1/z */
-	apply_z(sum, sum + num_words, z, curve);
+	uECC_vli_modInv(z, z, curve->p); /* z = 1/z */
+	apply_z(sum, sum + num_words, z);
 
 	/* Use Shamir's trick to calculate u1*G + u2*Q */
 	points[0] = 0;
 	points[1] = curve->G;
 	points[2] = _public;
 	points[3] = sum;
-	num_bits = smax(uECC_vli_numBits(u1, num_n_words),
-	uECC_vli_numBits(u2, num_n_words));
+	num_bits = smax(uECC_vli_numBits(u1),
+	uECC_vli_numBits(u2));
 
 	point = points[(!!uECC_vli_testBit(u1, num_bits - 1)) |
                        ((!!uECC_vli_testBit(u2, num_bits - 1)) << 1)];
-	uECC_vli_set(rx, point, num_words);
-	uECC_vli_set(ry, point + num_words, num_words);
-	uECC_vli_clear(z, num_words);
+	uECC_vli_set(rx, point);
+	uECC_vli_set(ry, point + num_words);
+	uECC_vli_clear(z);
 	z[0] = 1;
 
 	for (i = num_bits - 2; i >= 0; --i) {
@@ -283,25 +283,25 @@ int uECC_verify(const uint8_t *public_key, const uint8_t *message_hash,
 		index = (!!uECC_vli_testBit(u1, i)) | ((!!uECC_vli_testBit(u2, i)) << 1);
 		point = points[index];
 		if (point) {
-			uECC_vli_set(tx, point, num_words);
-			uECC_vli_set(ty, point + num_words, num_words);
-			apply_z(tx, ty, z, curve);
-			uECC_vli_modSub(tz, rx, tx, curve->p, num_words); /* Z = x2 - x1 */
+			uECC_vli_set(tx, point);
+			uECC_vli_set(ty, point + num_words);
+			apply_z(tx, ty, z);
+			uECC_vli_modSub(tz, rx, tx, curve->p); /* Z = x2 - x1 */
 			XYcZ_add(tx, ty, rx, ry, curve);
-			uECC_vli_modMult_fast(z, z, tz, curve);
+			uECC_vli_modMult_fast(z, z, tz);
 		}
   	}
 
-	uECC_vli_modInv(z, z, curve->p, num_words); /* Z = 1/Z */
-	apply_z(rx, ry, z, curve);
+	uECC_vli_modInv(z, z, curve->p); /* Z = 1/Z */
+	apply_z(rx, ry, z);
 
 	/* v = x1 (mod n) */
-	if (uECC_vli_cmp_unsafe(curve->n, rx, num_n_words) != 1) {
-		uECC_vli_sub(rx, rx, curve->n, num_n_words);
+	if (uECC_vli_cmp_unsafe(curve->n, rx) != 1) {
+		uECC_vli_sub(rx, rx, curve->n);
 	}
 
 	/* Accept only if v == r. */
-	return (int)(uECC_vli_equal(rx, r, num_words) == 0);
+	return (int)(uECC_vli_equal(rx, r) == 0);
 }
 #else
 typedef int mbedtls_dummy_tinycrypt_def;