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diff --git a/FreeRTOS-Plus/Source/WolfSSL/wolfcrypt/src/fe_448.c b/FreeRTOS-Plus/Source/WolfSSL/wolfcrypt/src/fe_448.c
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+/* fe_448.c
+ *
+ * Copyright (C) 2006-2020 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+/* Based On Daniel J Bernstein's curve25519 Public Domain ref10 work.
+ * Small implementation based on Daniel Beer's curve25519 public domain work.
+ * Reworked for curve448 by Sean Parkinson.
+ */
+
+#ifdef HAVE_CONFIG_H
+ #include <config.h>
+#endif
+
+#include <wolfssl/wolfcrypt/settings.h>
+
+#if defined(HAVE_CURVE448) || defined(HAVE_ED448)
+
+#include <wolfssl/wolfcrypt/fe_448.h>
+#include <stdint.h>
+
+#ifdef NO_INLINE
+ #include <wolfssl/wolfcrypt/misc.h>
+#else
+ #define WOLFSSL_MISC_INCLUDED
+ #include <wolfcrypt/src/misc.c>
+#endif
+
+#if defined(CURVE448_SMALL) || defined(ED448_SMALL)
+
+/* Initialize the field element operations.
+ */
+void fe448_init(void)
+{
+}
+
+/* Normalize the field element.
+ * Ensure result is in range: 0..2^448-2^224-2
+ *
+ * a [in] Field element in range 0..2^448-1.
+ */
+void fe448_norm(uint8_t* a)
+{
+ int i;
+ int16_t c = 0;
+ int16_t o = 0;
+
+ for (i = 0; i < 56; i++) {
+ c += a[i];
+ if ((i == 0) || (i == 28))
+ c += 1;
+ c >>= 8;
+ }
+
+ for (i = 0; i < 56; i++) {
+ if ((i == 0) || (i == 28)) o += c;
+ o += a[i];
+ a[i] = (uint8_t)o;
+ o >>= 8;
+ }
+}
+
+/* Copy one field element into another: d = a.
+ *
+ * d [in] Destination field element.
+ * a [in] Source field element.
+ */
+void fe448_copy(uint8_t* d, const uint8_t* a)
+{
+ int i;
+ for (i = 0; i < 56; i++) {
+ d[i] = a[i];
+ }
+}
+
+/* Conditionally swap the elements.
+ * Constant time implementation.
+ *
+ * a [in] First field element.
+ * b [in] Second field element.
+ * c [in] Swap when 1. Valid values: 0, 1.
+ */
+static void fe448_cswap(uint8_t* a, uint8_t* b, int c)
+{
+ int i;
+ uint8_t mask = -(uint8_t)c;
+ uint8_t t[56];
+
+ for (i = 0; i < 56; i++)
+ t[i] = (a[i] ^ b[i]) & mask;
+ for (i = 0; i < 56; i++)
+ a[i] ^= t[i];
+ for (i = 0; i < 56; i++)
+ b[i] ^= t[i];
+}
+
+/* Add two field elements. r = (a + b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold sum.
+ * a [in] Field element to add.
+ * b [in] Field element to add.
+ */
+void fe448_add(uint8_t* r, const uint8_t* a, const uint8_t* b)
+{
+ int i;
+ int16_t c = 0;
+ int16_t o = 0;
+
+ for (i = 0; i < 56; i++) {
+ c += a[i];
+ c += b[i];
+ r[i] = (uint8_t)c;
+ c >>= 8;
+ }
+
+ for (i = 0; i < 56; i++) {
+ if ((i == 0) || (i == 28)) o += c;
+ o += r[i];
+ r[i] = (uint8_t)o;
+ o >>= 8;
+ }
+}
+
+/* Subtract a field element from another. r = (a - b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold difference.
+ * a [in] Field element to subtract from.
+ * b [in] Field element to subtract.
+ */
+void fe448_sub(uint8_t* r, const uint8_t* a, const uint8_t* b)
+{
+ int i;
+ int16_t c = 0;
+ int16_t o = 0;
+
+ for (i = 0; i < 56; i++) {
+ if (i == 28)
+ c += 0x1fc;
+ else
+ c += 0x1fe;
+ c += a[i];
+ c -= b[i];
+ r[i] = (uint8_t)c;
+ c >>= 8;
+ }
+
+ for (i = 0; i < 56; i++) {
+ if ((i == 0) || (i == 28)) o += c;
+ o += r[i];
+ r[i] = (uint8_t)o;
+ o >>= 8;
+ }
+}
+
+/* Mulitply a field element by 39081. r = (39081 * a) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to multiply.
+ */
+void fe448_mul39081(uint8_t* r, const uint8_t* a)
+{
+ int i;
+ int32_t c = 0;
+ int32_t o = 0;
+
+ for (i = 0; i < 56; i++) {
+ c += a[i] * (int32_t)39081;
+ r[i] = (uint8_t)c;
+ c >>= 8;
+ }
+
+ for (i = 0; i < 56; i++) {
+ if ((i == 0) || (i == 28)) o += c;
+ o += r[i];
+ r[i] = (uint8_t)o;
+ o >>= 8;
+ }
+}
+
+/* Mulitply two field elements. r = (a * b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to multiply.
+ * b [in] Field element to multiply.
+ */
+void fe448_mul(uint8_t* r, const uint8_t* a, const uint8_t* b)
+{
+ int i, k;
+ int32_t c = 0;
+ int16_t o = 0, cc = 0;
+ uint8_t t[112];
+
+ for (k = 0; k < 56; k++) {
+ i = 0;
+ for (; i <= k; i++) {
+ c += (int32_t)a[i] * b[k - i];
+ }
+ t[k] = (uint8_t)c;
+ c >>= 8;
+ }
+ for (; k < 111; k++) {
+ i = k - 55;
+ for (; i < 56; i++) {
+ c += (int32_t)a[i] * b[k - i];
+ }
+ t[k] = (uint8_t)c;
+ c >>= 8;
+ }
+ t[k] = (uint8_t)c;
+
+ for (i = 0; i < 28; i++) {
+ o += t[i];
+ o += t[i + 56];
+ o += t[i + 84];
+ r[i] = (uint8_t)o;
+ o >>= 8;
+ }
+ for (i = 28; i < 56; i++) {
+ o += t[i];
+ o += t[i + 56];
+ o += t[i + 28];
+ o += t[i + 56];
+ r[i] = (uint8_t)o;
+ o >>= 8;
+ }
+ for (i = 0; i < 56; i++) {
+ if ((i == 0) || (i == 28)) cc += o;
+ cc += r[i];
+ r[i] = (uint8_t)cc;
+ cc >>= 8;
+ }
+}
+
+/* Square a field element. r = (a * a) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to square.
+ */
+void fe448_sqr(uint8_t* r, const uint8_t* a)
+{
+ int i, k;
+ int32_t c = 0;
+ int32_t p;
+ int16_t o = 0, cc = 0;
+ uint8_t t[112];
+
+ for (k = 0; k < 56; k++) {
+ i = 0;
+ for (; i <= k; i++) {
+ if (k - i < i)
+ break;
+ p = (int32_t)a[i] * a[k - i];
+ if (k - i != i)
+ p *= 2;
+ c += p;
+ }
+ t[k] = (uint8_t)c;
+ c >>= 8;
+ }
+ for (; k < 111; k++) {
+ i = k - 55;
+ for (; i < 56; i++) {
+ if (k - i < i)
+ break;
+ p = (int32_t)a[i] * a[k - i];
+ if (k - i != i)
+ p *= 2;
+ c += p;
+ }
+ t[k] = (uint8_t)c;
+ c >>= 8;
+ }
+ t[k] = (uint8_t)c;
+
+ for (i = 0; i < 28; i++) {
+ o += t[i];
+ o += t[i + 56];
+ o += t[i + 84];
+ r[i] = (uint8_t)o;
+ o >>= 8;
+ }
+ for (i = 28; i < 56; i++) {
+ o += t[i];
+ o += t[i + 56];
+ o += t[i + 28];
+ o += t[i + 56];
+ r[i] = (uint8_t)o;
+ o >>= 8;
+ }
+ for (i = 0; i < 56; i++) {
+ if ((i == 0) || (i == 28)) cc += o;
+ cc += r[i];
+ r[i] = (uint8_t)cc;
+ cc >>= 8;
+ }
+ fe448_norm(r);
+}
+
+/* Invert the field element. (r * a) mod (2^448 - 2^224 - 1) = 1
+ * Constant time implementation - using Fermat's little theorem:
+ * a^(p-1) mod p = 1 => a^(p-2) mod p = 1/a
+ * For curve448: p - 2 = 2^448 - 2^224 - 3
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to invert.
+ */
+void fe448_invert(uint8_t* r, const uint8_t* a)
+{
+ int i;
+ uint8_t t[56];
+
+ fe448_sqr(t, a);
+ fe448_mul(t, t, a);
+ for (i = 0; i < 221; i++) {
+ fe448_sqr(t, t);
+ fe448_mul(t, t, a);
+ }
+ fe448_sqr(t, t);
+ for (i = 0; i < 222; i++) {
+ fe448_sqr(t, t);
+ fe448_mul(t, t, a);
+ }
+ fe448_sqr(t, t);
+ fe448_sqr(t, t);
+ fe448_mul(r, t, a);
+}
+
+/* Scalar multiply the point by a number. r = n.a
+ * Uses Montogmery ladder and only requires the x-ordinate.
+ *
+ * r [in] Field element to hold result.
+ * n [in] Scalar as an array of bytes.
+ * a [in] Point to multiply - x-ordinate only.
+ */
+int curve448(byte* r, const byte* n, const byte* a)
+{
+ uint8_t x1[56];
+ uint8_t x2[56] = {1};
+ uint8_t z2[56] = {0};
+ uint8_t x3[56];
+ uint8_t z3[56] = {1};
+ uint8_t t0[56];
+ uint8_t t1[56];
+ int i;
+ unsigned int swap;
+ unsigned int b;
+
+ fe448_copy(x1, a);
+ fe448_copy(x3, a);
+
+ swap = 0;
+ for (i = 447; i >= 0; --i) {
+ b = (n[i >> 3] >> (i & 7)) & 1;
+ swap ^= b;
+ fe448_cswap(x2, x3, swap);
+ fe448_cswap(z2, z3, swap);
+ swap = b;
+
+ /* Montgomery Ladder - double and add */
+ fe448_add(t0, x2, z2);
+ fe448_add(t1, x3, z3);
+ fe448_sub(x2, x2, z2);
+ fe448_sub(x3, x3, z3);
+ fe448_mul(t1, t1, x2);
+ fe448_mul(z3, x3, t0);
+ fe448_sqr(t0, t0);
+ fe448_sqr(x2, x2);
+ fe448_add(x3, z3, t1);
+ fe448_sqr(x3, x3);
+ fe448_sub(z3, z3, t1);
+ fe448_sqr(z3, z3);
+ fe448_mul(z3, z3, x1);
+ fe448_sub(t1, t0, x2);
+ fe448_mul(x2, t0, x2);
+ fe448_mul39081(z2, t1);
+ fe448_add(z2, t0, z2);
+ fe448_mul(z2, z2, t1);
+ }
+ fe448_cswap(x2, x3, swap);
+ fe448_cswap(z2, z3, swap);
+
+ fe448_invert(z2, z2);
+ fe448_mul(r, x2, z2);
+ fe448_norm(r);
+
+ return 0;
+}
+
+#ifdef HAVE_ED448
+/* Check whether field element is not 0.
+ * Field element must have been normalized before call.
+ *
+ * a [in] Field element.
+ * returns 0 when zero, and any other value otherwise.
+ */
+int fe448_isnonzero(const uint8_t* a)
+{
+ int i;
+ uint8_t c = 0;
+ for (i = 0; i < 56; i++)
+ c |= a[i];
+ return c;
+}
+
+/* Negates the field element. r = -a mod (2^448 - 2^224 - 1)
+ * Add 0x200 to each element and subtract 2 from next.
+ * Top element overflow handled by subtracting 2 from index 0 and 28.
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element.
+ */
+void fe448_neg(uint8_t* r, const uint8_t* a)
+{
+ int i;
+ int16_t c = 0;
+ int16_t o = 0;
+
+ for (i = 0; i < 56; i++) {
+ if (i == 28)
+ c += 0x1fc;
+ else
+ c += 0x1fe;
+ c -= a[i];
+ r[i] = (uint8_t)c;
+ c >>= 8;
+ }
+
+ for (i = 0; i < 56; i++) {
+ if ((i == 0) || (i == 28)) o += c;
+ o += r[i];
+ r[i] = (uint8_t)o;
+ o >>= 8;
+ }
+}
+
+/* Raise field element to (p-3) / 4: 2^446 - 2^222 - 1
+ * Used for calcualting y-ordinate from x-ordinate for Ed448.
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to exponentiate.
+ */
+void fe448_pow_2_446_222_1(uint8_t* r, const uint8_t* a)
+{
+ int i;
+ uint8_t t[56];
+
+ fe448_sqr(t, a);
+ fe448_mul(t, t, a);
+ for (i = 0; i < 221; i++) {
+ fe448_sqr(t, t);
+ fe448_mul(t, t, a);
+ }
+ fe448_sqr(t, t);
+ for (i = 0; i < 221; i++) {
+ fe448_sqr(t, t);
+ fe448_mul(t, t, a);
+ }
+ fe448_sqr(t, t);
+ fe448_mul(r, t, a);
+}
+
+/* Constant time, conditional move of b into a.
+ * a is not changed if the condition is 0.
+ *
+ * a A field element.
+ * b A field element.
+ * c If 1 then copy and if 0 then don't copy.
+ */
+void fe448_cmov(uint8_t* a, const uint8_t* b, int c)
+{
+ int i;
+ uint8_t m = -(uint8_t)c;
+ uint8_t t[56];
+
+ for (i = 0; i < 56; i++)
+ t[i] = m & (a[i] ^ b[i]);
+ for (i = 0; i < 56; i++)
+ a[i] ^= t[i];
+}
+
+#endif /* HAVE_ED448 */
+#elif defined(CURVED448_128BIT)
+
+/* Initialize the field element operations.
+ */
+void fe448_init(void)
+{
+}
+
+/* Convert the field element from a byte array to an array of 56-bits.
+ *
+ * r [in] Array to encode into.
+ * b [in] Byte array.
+ */
+void fe448_from_bytes(int64_t* r, const unsigned char* b)
+{
+ r[ 0] = ((int64_t) (b[ 0]) << 0)
+ | ((int64_t) (b[ 1]) << 8)
+ | ((int64_t) (b[ 2]) << 16)
+ | ((int64_t) (b[ 3]) << 24)
+ | ((int64_t) (b[ 4]) << 32)
+ | ((int64_t) (b[ 5]) << 40)
+ | ((int64_t) (b[ 6]) << 48);
+ r[ 1] = ((int64_t) (b[ 7]) << 0)
+ | ((int64_t) (b[ 8]) << 8)
+ | ((int64_t) (b[ 9]) << 16)
+ | ((int64_t) (b[10]) << 24)
+ | ((int64_t) (b[11]) << 32)
+ | ((int64_t) (b[12]) << 40)
+ | ((int64_t) (b[13]) << 48);
+ r[ 2] = ((int64_t) (b[14]) << 0)
+ | ((int64_t) (b[15]) << 8)
+ | ((int64_t) (b[16]) << 16)
+ | ((int64_t) (b[17]) << 24)
+ | ((int64_t) (b[18]) << 32)
+ | ((int64_t) (b[19]) << 40)
+ | ((int64_t) (b[20]) << 48);
+ r[ 3] = ((int64_t) (b[21]) << 0)
+ | ((int64_t) (b[22]) << 8)
+ | ((int64_t) (b[23]) << 16)
+ | ((int64_t) (b[24]) << 24)
+ | ((int64_t) (b[25]) << 32)
+ | ((int64_t) (b[26]) << 40)
+ | ((int64_t) (b[27]) << 48);
+ r[ 4] = ((int64_t) (b[28]) << 0)
+ | ((int64_t) (b[29]) << 8)
+ | ((int64_t) (b[30]) << 16)
+ | ((int64_t) (b[31]) << 24)
+ | ((int64_t) (b[32]) << 32)
+ | ((int64_t) (b[33]) << 40)
+ | ((int64_t) (b[34]) << 48);
+ r[ 5] = ((int64_t) (b[35]) << 0)
+ | ((int64_t) (b[36]) << 8)
+ | ((int64_t) (b[37]) << 16)
+ | ((int64_t) (b[38]) << 24)
+ | ((int64_t) (b[39]) << 32)
+ | ((int64_t) (b[40]) << 40)
+ | ((int64_t) (b[41]) << 48);
+ r[ 6] = ((int64_t) (b[42]) << 0)
+ | ((int64_t) (b[43]) << 8)
+ | ((int64_t) (b[44]) << 16)
+ | ((int64_t) (b[45]) << 24)
+ | ((int64_t) (b[46]) << 32)
+ | ((int64_t) (b[47]) << 40)
+ | ((int64_t) (b[48]) << 48);
+ r[ 7] = ((int64_t) (b[49]) << 0)
+ | ((int64_t) (b[50]) << 8)
+ | ((int64_t) (b[51]) << 16)
+ | ((int64_t) (b[52]) << 24)
+ | ((int64_t) (b[53]) << 32)
+ | ((int64_t) (b[54]) << 40)
+ | ((int64_t) (b[55]) << 48);
+}
+
+/* Convert the field element to a byte array from an array of 56-bits.
+ *
+ * b [in] Byte array.
+ * a [in] Array to encode into.
+ */
+void fe448_to_bytes(unsigned char* b, const int64_t* a)
+{
+ int128_t t;
+ /* Mod */
+ int64_t in0 = a[0];
+ int64_t in1 = a[1];
+ int64_t in2 = a[2];
+ int64_t in3 = a[3];
+ int64_t in4 = a[4];
+ int64_t in5 = a[5];
+ int64_t in6 = a[6];
+ int64_t in7 = a[7];
+ int64_t o = in7 >> 56;
+ in7 -= o << 56;
+ in0 += o;
+ in4 += o;
+ o = (in0 + 1) >> 56;
+ o = (o + in1) >> 56;
+ o = (o + in2) >> 56;
+ o = (o + in3) >> 56;
+ o = (o + in4 + 1) >> 56;
+ o = (o + in5) >> 56;
+ o = (o + in6) >> 56;
+ o = (o + in7) >> 56;
+ in0 += o;
+ in4 += o;
+ in7 -= o << 56;
+ o = in0 >> 56; in1 += o; t = o << 56; in0 -= t;
+ o = in1 >> 56; in2 += o; t = o << 56; in1 -= t;
+ o = in2 >> 56; in3 += o; t = o << 56; in2 -= t;
+ o = in3 >> 56; in4 += o; t = o << 56; in3 -= t;
+ o = in4 >> 56; in5 += o; t = o << 56; in4 -= t;
+ o = in5 >> 56; in6 += o; t = o << 56; in5 -= t;
+ o = in6 >> 56; in7 += o; t = o << 56; in6 -= t;
+ o = in7 >> 56; in0 += o;
+ in4 += o; t = o << 56; in7 -= t;
+
+ /* Output as bytes */
+ b[ 0] = (in0 >> 0);
+ b[ 1] = (in0 >> 8);
+ b[ 2] = (in0 >> 16);
+ b[ 3] = (in0 >> 24);
+ b[ 4] = (in0 >> 32);
+ b[ 5] = (in0 >> 40);
+ b[ 6] = (in0 >> 48);
+ b[ 7] = (in1 >> 0);
+ b[ 8] = (in1 >> 8);
+ b[ 9] = (in1 >> 16);
+ b[10] = (in1 >> 24);
+ b[11] = (in1 >> 32);
+ b[12] = (in1 >> 40);
+ b[13] = (in1 >> 48);
+ b[14] = (in2 >> 0);
+ b[15] = (in2 >> 8);
+ b[16] = (in2 >> 16);
+ b[17] = (in2 >> 24);
+ b[18] = (in2 >> 32);
+ b[19] = (in2 >> 40);
+ b[20] = (in2 >> 48);
+ b[21] = (in3 >> 0);
+ b[22] = (in3 >> 8);
+ b[23] = (in3 >> 16);
+ b[24] = (in3 >> 24);
+ b[25] = (in3 >> 32);
+ b[26] = (in3 >> 40);
+ b[27] = (in3 >> 48);
+ b[28] = (in4 >> 0);
+ b[29] = (in4 >> 8);
+ b[30] = (in4 >> 16);
+ b[31] = (in4 >> 24);
+ b[32] = (in4 >> 32);
+ b[33] = (in4 >> 40);
+ b[34] = (in4 >> 48);
+ b[35] = (in5 >> 0);
+ b[36] = (in5 >> 8);
+ b[37] = (in5 >> 16);
+ b[38] = (in5 >> 24);
+ b[39] = (in5 >> 32);
+ b[40] = (in5 >> 40);
+ b[41] = (in5 >> 48);
+ b[42] = (in6 >> 0);
+ b[43] = (in6 >> 8);
+ b[44] = (in6 >> 16);
+ b[45] = (in6 >> 24);
+ b[46] = (in6 >> 32);
+ b[47] = (in6 >> 40);
+ b[48] = (in6 >> 48);
+ b[49] = (in7 >> 0);
+ b[50] = (in7 >> 8);
+ b[51] = (in7 >> 16);
+ b[52] = (in7 >> 24);
+ b[53] = (in7 >> 32);
+ b[54] = (in7 >> 40);
+ b[55] = (in7 >> 48);
+}
+
+/* Set the field element to 0.
+ *
+ * a [in] Field element.
+ */
+void fe448_1(int64_t* a)
+{
+ a[0] = 1;
+ a[1] = 0;
+ a[2] = 0;
+ a[3] = 0;
+ a[4] = 0;
+ a[5] = 0;
+ a[6] = 0;
+ a[7] = 0;
+}
+
+/* Set the field element to 0.
+ *
+ * a [in] Field element.
+ */
+void fe448_0(int64_t* a)
+{
+ a[0] = 0;
+ a[1] = 0;
+ a[2] = 0;
+ a[3] = 0;
+ a[4] = 0;
+ a[5] = 0;
+ a[6] = 0;
+ a[7] = 0;
+}
+
+/* Copy one field element into another: d = a.
+ *
+ * d [in] Destination field element.
+ * a [in] Source field element.
+ */
+void fe448_copy(int64_t* d, const int64_t* a)
+{
+ d[0] = a[0];
+ d[1] = a[1];
+ d[2] = a[2];
+ d[3] = a[3];
+ d[4] = a[4];
+ d[5] = a[5];
+ d[6] = a[6];
+ d[7] = a[7];
+}
+
+/* Conditionally swap the elements.
+ * Constant time implementation.
+ *
+ * a [in] First field element.
+ * b [in] Second field element.
+ * c [in] Swap when 1. Valid values: 0, 1.
+ */
+static void fe448_cswap(int64_t* a, int64_t* b, int c)
+{
+ int64_t mask = -(int64_t)c;
+ int64_t t0 = (a[0] ^ b[0]) & mask;
+ int64_t t1 = (a[1] ^ b[1]) & mask;
+ int64_t t2 = (a[2] ^ b[2]) & mask;
+ int64_t t3 = (a[3] ^ b[3]) & mask;
+ int64_t t4 = (a[4] ^ b[4]) & mask;
+ int64_t t5 = (a[5] ^ b[5]) & mask;
+ int64_t t6 = (a[6] ^ b[6]) & mask;
+ int64_t t7 = (a[7] ^ b[7]) & mask;
+ a[0] ^= t0;
+ a[1] ^= t1;
+ a[2] ^= t2;
+ a[3] ^= t3;
+ a[4] ^= t4;
+ a[5] ^= t5;
+ a[6] ^= t6;
+ a[7] ^= t7;
+ b[0] ^= t0;
+ b[1] ^= t1;
+ b[2] ^= t2;
+ b[3] ^= t3;
+ b[4] ^= t4;
+ b[5] ^= t5;
+ b[6] ^= t6;
+ b[7] ^= t7;
+}
+
+/* Add two field elements. r = (a + b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold sum.
+ * a [in] Field element to add.
+ * b [in] Field element to add.
+ */
+void fe448_add(int64_t* r, const int64_t* a, const int64_t* b)
+{
+ r[0] = a[0] + b[0];
+ r[1] = a[1] + b[1];
+ r[2] = a[2] + b[2];
+ r[3] = a[3] + b[3];
+ r[4] = a[4] + b[4];
+ r[5] = a[5] + b[5];
+ r[6] = a[6] + b[6];
+ r[7] = a[7] + b[7];
+}
+
+/* Subtract a field element from another. r = (a - b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold difference.
+ * a [in] Field element to subtract from.
+ * b [in] Field element to subtract.
+ */
+void fe448_sub(int64_t* r, const int64_t* a, const int64_t* b)
+{
+ r[0] = a[0] - b[0];
+ r[1] = a[1] - b[1];
+ r[2] = a[2] - b[2];
+ r[3] = a[3] - b[3];
+ r[4] = a[4] - b[4];
+ r[5] = a[5] - b[5];
+ r[6] = a[6] - b[6];
+ r[7] = a[7] - b[7];
+}
+
+/* Mulitply a field element by 39081. r = (39081 * a) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to multiply.
+ */
+void fe448_mul39081(int64_t* r, const int64_t* a)
+{
+ int128_t t;
+ int64_t o;
+ int128_t t0 = a[0] * (int128_t)39081;
+ int128_t t1 = a[1] * (int128_t)39081;
+ int128_t t2 = a[2] * (int128_t)39081;
+ int128_t t3 = a[3] * (int128_t)39081;
+ int128_t t4 = a[4] * (int128_t)39081;
+ int128_t t5 = a[5] * (int128_t)39081;
+ int128_t t6 = a[6] * (int128_t)39081;
+ int128_t t7 = a[7] * (int128_t)39081;
+ o = t0 >> 56; t1 += o; t = (int128_t)o << 56; t0 -= t;
+ o = t1 >> 56; t2 += o; t = (int128_t)o << 56; t1 -= t;
+ o = t2 >> 56; t3 += o; t = (int128_t)o << 56; t2 -= t;
+ o = t3 >> 56; t4 += o; t = (int128_t)o << 56; t3 -= t;
+ o = t4 >> 56; t5 += o; t = (int128_t)o << 56; t4 -= t;
+ o = t5 >> 56; t6 += o; t = (int128_t)o << 56; t5 -= t;
+ o = t6 >> 56; t7 += o; t = (int128_t)o << 56; t6 -= t;
+ o = t7 >> 56; t0 += o;
+ t4 += o; t = (int128_t)o << 56; t7 -= t;
+
+ /* Store */
+ r[0] = t0;
+ r[1] = t1;
+ r[2] = t2;
+ r[3] = t3;
+ r[4] = t4;
+ r[5] = t5;
+ r[6] = t6;
+ r[7] = t7;
+}
+
+/* Mulitply two field elements. r = (a * b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to multiply.
+ * b [in] Field element to multiply.
+ */
+void fe448_mul(int64_t* r, const int64_t* a, const int64_t* b)
+{
+ int128_t t;
+ int64_t o;
+ int128_t t0 = (int128_t)a[ 0] * b[ 0];
+ int128_t t1 = (int128_t)a[ 0] * b[ 1];
+ int128_t t101 = (int128_t)a[ 1] * b[ 0];
+ int128_t t2 = (int128_t)a[ 0] * b[ 2];
+ int128_t t102 = (int128_t)a[ 1] * b[ 1];
+ int128_t t202 = (int128_t)a[ 2] * b[ 0];
+ int128_t t3 = (int128_t)a[ 0] * b[ 3];
+ int128_t t103 = (int128_t)a[ 1] * b[ 2];
+ int128_t t203 = (int128_t)a[ 2] * b[ 1];
+ int128_t t303 = (int128_t)a[ 3] * b[ 0];
+ int128_t t4 = (int128_t)a[ 0] * b[ 4];
+ int128_t t104 = (int128_t)a[ 1] * b[ 3];
+ int128_t t204 = (int128_t)a[ 2] * b[ 2];
+ int128_t t304 = (int128_t)a[ 3] * b[ 1];
+ int128_t t404 = (int128_t)a[ 4] * b[ 0];
+ int128_t t5 = (int128_t)a[ 0] * b[ 5];
+ int128_t t105 = (int128_t)a[ 1] * b[ 4];
+ int128_t t205 = (int128_t)a[ 2] * b[ 3];
+ int128_t t305 = (int128_t)a[ 3] * b[ 2];
+ int128_t t405 = (int128_t)a[ 4] * b[ 1];
+ int128_t t505 = (int128_t)a[ 5] * b[ 0];
+ int128_t t6 = (int128_t)a[ 0] * b[ 6];
+ int128_t t106 = (int128_t)a[ 1] * b[ 5];
+ int128_t t206 = (int128_t)a[ 2] * b[ 4];
+ int128_t t306 = (int128_t)a[ 3] * b[ 3];
+ int128_t t406 = (int128_t)a[ 4] * b[ 2];
+ int128_t t506 = (int128_t)a[ 5] * b[ 1];
+ int128_t t606 = (int128_t)a[ 6] * b[ 0];
+ int128_t t7 = (int128_t)a[ 0] * b[ 7];
+ int128_t t107 = (int128_t)a[ 1] * b[ 6];
+ int128_t t207 = (int128_t)a[ 2] * b[ 5];
+ int128_t t307 = (int128_t)a[ 3] * b[ 4];
+ int128_t t407 = (int128_t)a[ 4] * b[ 3];
+ int128_t t507 = (int128_t)a[ 5] * b[ 2];
+ int128_t t607 = (int128_t)a[ 6] * b[ 1];
+ int128_t t707 = (int128_t)a[ 7] * b[ 0];
+ int128_t t8 = (int128_t)a[ 1] * b[ 7];
+ int128_t t108 = (int128_t)a[ 2] * b[ 6];
+ int128_t t208 = (int128_t)a[ 3] * b[ 5];
+ int128_t t308 = (int128_t)a[ 4] * b[ 4];
+ int128_t t408 = (int128_t)a[ 5] * b[ 3];
+ int128_t t508 = (int128_t)a[ 6] * b[ 2];
+ int128_t t608 = (int128_t)a[ 7] * b[ 1];
+ int128_t t9 = (int128_t)a[ 2] * b[ 7];
+ int128_t t109 = (int128_t)a[ 3] * b[ 6];
+ int128_t t209 = (int128_t)a[ 4] * b[ 5];
+ int128_t t309 = (int128_t)a[ 5] * b[ 4];
+ int128_t t409 = (int128_t)a[ 6] * b[ 3];
+ int128_t t509 = (int128_t)a[ 7] * b[ 2];
+ int128_t t10 = (int128_t)a[ 3] * b[ 7];
+ int128_t t110 = (int128_t)a[ 4] * b[ 6];
+ int128_t t210 = (int128_t)a[ 5] * b[ 5];
+ int128_t t310 = (int128_t)a[ 6] * b[ 4];
+ int128_t t410 = (int128_t)a[ 7] * b[ 3];
+ int128_t t11 = (int128_t)a[ 4] * b[ 7];
+ int128_t t111 = (int128_t)a[ 5] * b[ 6];
+ int128_t t211 = (int128_t)a[ 6] * b[ 5];
+ int128_t t311 = (int128_t)a[ 7] * b[ 4];
+ int128_t t12 = (int128_t)a[ 5] * b[ 7];
+ int128_t t112 = (int128_t)a[ 6] * b[ 6];
+ int128_t t212 = (int128_t)a[ 7] * b[ 5];
+ int128_t t13 = (int128_t)a[ 6] * b[ 7];
+ int128_t t113 = (int128_t)a[ 7] * b[ 6];
+ int128_t t14 = (int128_t)a[ 7] * b[ 7];
+ t1 += t101;
+ t2 += t102; t2 += t202;
+ t3 += t103; t3 += t203; t3 += t303;
+ t4 += t104; t4 += t204; t4 += t304; t4 += t404;
+ t5 += t105; t5 += t205; t5 += t305; t5 += t405; t5 += t505;
+ t6 += t106; t6 += t206; t6 += t306; t6 += t406; t6 += t506;
+ t6 += t606;
+ t7 += t107; t7 += t207; t7 += t307; t7 += t407; t7 += t507;
+ t7 += t607;
+ t7 += t707;
+ t8 += t108; t8 += t208; t8 += t308; t8 += t408; t8 += t508;
+ t8 += t608;
+ t9 += t109; t9 += t209; t9 += t309; t9 += t409; t9 += t509;
+ t10 += t110; t10 += t210; t10 += t310; t10 += t410;
+ t11 += t111; t11 += t211; t11 += t311;
+ t12 += t112; t12 += t212;
+ t13 += t113;
+
+ /* Reduce */
+ t0 += t8 + t12;
+ t1 += t9 + t13;
+ t2 += t10 + t14;
+ t3 += t11;
+ t4 += t12 + t8 + t12;
+ t5 += t13 + t9 + t13;
+ t6 += t14 + t10 + t14;
+ t7 += t11;
+ o = t7 >> 56; t0 += o;
+ t4 += o; t = (int128_t)o << 56; t7 -= t;
+ o = t0 >> 56; t1 += o; t = (int128_t)o << 56; t0 -= t;
+ o = t1 >> 56; t2 += o; t = (int128_t)o << 56; t1 -= t;
+ o = t2 >> 56; t3 += o; t = (int128_t)o << 56; t2 -= t;
+ o = t3 >> 56; t4 += o; t = (int128_t)o << 56; t3 -= t;
+ o = t4 >> 56; t5 += o; t = (int128_t)o << 56; t4 -= t;
+ o = t5 >> 56; t6 += o; t = (int128_t)o << 56; t5 -= t;
+ o = t6 >> 56; t7 += o; t = (int128_t)o << 56; t6 -= t;
+ o = t7 >> 56; t0 += o;
+ t4 += o; t = (int128_t)o << 56; t7 -= t;
+
+ /* Store */
+ r[0] = t0;
+ r[1] = t1;
+ r[2] = t2;
+ r[3] = t3;
+ r[4] = t4;
+ r[5] = t5;
+ r[6] = t6;
+ r[7] = t7;
+}
+
+/* Square a field element. r = (a * a) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to square.
+ */
+void fe448_sqr(int64_t* r, const int64_t* a)
+{
+ int128_t t;
+ int64_t o;
+ int128_t t0 = (int128_t)a[ 0] * a[ 0];
+ int128_t t1 = 2 * (int128_t)a[ 0] * a[ 1];
+ int128_t t2 = 2 * (int128_t)a[ 0] * a[ 2];
+ int128_t t102 = (int128_t)a[ 1] * a[ 1];
+ int128_t t3 = 2 * (int128_t)a[ 0] * a[ 3];
+ int128_t t103 = 2 * (int128_t)a[ 1] * a[ 2];
+ int128_t t4 = 2 * (int128_t)a[ 0] * a[ 4];
+ int128_t t104 = 2 * (int128_t)a[ 1] * a[ 3];
+ int128_t t204 = (int128_t)a[ 2] * a[ 2];
+ int128_t t5 = 2 * (int128_t)a[ 0] * a[ 5];
+ int128_t t105 = 2 * (int128_t)a[ 1] * a[ 4];
+ int128_t t205 = 2 * (int128_t)a[ 2] * a[ 3];
+ int128_t t6 = 2 * (int128_t)a[ 0] * a[ 6];
+ int128_t t106 = 2 * (int128_t)a[ 1] * a[ 5];
+ int128_t t206 = 2 * (int128_t)a[ 2] * a[ 4];
+ int128_t t306 = (int128_t)a[ 3] * a[ 3];
+ int128_t t7 = 2 * (int128_t)a[ 0] * a[ 7];
+ int128_t t107 = 2 * (int128_t)a[ 1] * a[ 6];
+ int128_t t207 = 2 * (int128_t)a[ 2] * a[ 5];
+ int128_t t307 = 2 * (int128_t)a[ 3] * a[ 4];
+ int128_t t8 = 2 * (int128_t)a[ 1] * a[ 7];
+ int128_t t108 = 2 * (int128_t)a[ 2] * a[ 6];
+ int128_t t208 = 2 * (int128_t)a[ 3] * a[ 5];
+ int128_t t308 = (int128_t)a[ 4] * a[ 4];
+ int128_t t9 = 2 * (int128_t)a[ 2] * a[ 7];
+ int128_t t109 = 2 * (int128_t)a[ 3] * a[ 6];
+ int128_t t209 = 2 * (int128_t)a[ 4] * a[ 5];
+ int128_t t10 = 2 * (int128_t)a[ 3] * a[ 7];
+ int128_t t110 = 2 * (int128_t)a[ 4] * a[ 6];
+ int128_t t210 = (int128_t)a[ 5] * a[ 5];
+ int128_t t11 = 2 * (int128_t)a[ 4] * a[ 7];
+ int128_t t111 = 2 * (int128_t)a[ 5] * a[ 6];
+ int128_t t12 = 2 * (int128_t)a[ 5] * a[ 7];
+ int128_t t112 = (int128_t)a[ 6] * a[ 6];
+ int128_t t13 = 2 * (int128_t)a[ 6] * a[ 7];
+ int128_t t14 = (int128_t)a[ 7] * a[ 7];
+ t2 += t102;
+ t3 += t103;
+ t4 += t104; t4 += t204;
+ t5 += t105; t5 += t205;
+ t6 += t106; t6 += t206; t6 += t306;
+ t7 += t107; t7 += t207; t7 += t307;
+ t8 += t108; t8 += t208; t8 += t308;
+ t9 += t109; t9 += t209;
+ t10 += t110; t10 += t210;
+ t11 += t111;
+ t12 += t112;
+
+ /* Reduce */
+ t0 += t8 + t12;
+ t1 += t9 + t13;
+ t2 += t10 + t14;
+ t3 += t11;
+ t4 += t12 + t8 + t12;
+ t5 += t13 + t9 + t13;
+ t6 += t14 + t10 + t14;
+ t7 += t11;
+ o = t7 >> 56; t0 += o;
+ t4 += o; t = (int128_t)o << 56; t7 -= t;
+ o = t0 >> 56; t1 += o; t = (int128_t)o << 56; t0 -= t;
+ o = t1 >> 56; t2 += o; t = (int128_t)o << 56; t1 -= t;
+ o = t2 >> 56; t3 += o; t = (int128_t)o << 56; t2 -= t;
+ o = t3 >> 56; t4 += o; t = (int128_t)o << 56; t3 -= t;
+ o = t4 >> 56; t5 += o; t = (int128_t)o << 56; t4 -= t;
+ o = t5 >> 56; t6 += o; t = (int128_t)o << 56; t5 -= t;
+ o = t6 >> 56; t7 += o; t = (int128_t)o << 56; t6 -= t;
+ o = t7 >> 56; t0 += o;
+ t4 += o; t = (int128_t)o << 56; t7 -= t;
+
+ /* Store */
+ r[0] = t0;
+ r[1] = t1;
+ r[2] = t2;
+ r[3] = t3;
+ r[4] = t4;
+ r[5] = t5;
+ r[6] = t6;
+ r[7] = t7;
+}
+
+/* Invert the field element. (r * a) mod (2^448 - 2^224 - 1) = 1
+ * Constant time implementation - using Fermat's little theorem:
+ * a^(p-1) mod p = 1 => a^(p-2) mod p = 1/a
+ * For curve448: p - 2 = 2^448 - 2^224 - 3
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to invert.
+ */
+void fe448_invert(int64_t* r, const int64_t* a)
+{
+ int64_t t1[8];
+ int64_t t2[8];
+ int64_t t3[8];
+ int64_t t4[8];
+ int i;
+
+ fe448_sqr(t1, a);
+ /* t1 = 2 */
+ fe448_mul(t1, t1, a);
+ /* t1 = 3 */
+ fe448_sqr(t2, t1); for (i = 1; i < 2; ++i) fe448_sqr(t2, t2);
+ /* t2 = c */
+ fe448_mul(t3, t2, a);
+ /* t3 = d */
+ fe448_mul(t1, t2, t1);
+ /* t1 = f */
+ fe448_sqr(t2, t1);
+ /* t2 = 1e */
+ fe448_mul(t4, t2, a);
+ /* t4 = 1f */
+ fe448_sqr(t2, t4); for (i = 1; i < 5; ++i) fe448_sqr(t2, t2);
+ /* t2 = 3e0 */
+ fe448_mul(t1, t2, t4);
+ /* t1 = 3ff */
+ fe448_sqr(t2, t1); for (i = 1; i < 10; ++i) fe448_sqr(t2, t2);
+ /* t2 = ffc00 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = fffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 5; ++i) fe448_sqr(t2, t2);
+ /* t2 = 1ffffe0 */
+ fe448_mul(t1, t2, t4);
+ /* t1 = 1ffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 25; ++i) fe448_sqr(t2, t2);
+ /* t2 = 3fffffe000000 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = 3ffffffffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 5; ++i) fe448_sqr(t2, t2);
+ /* t2 = 7fffffffffffe0 */
+ fe448_mul(t1, t2, t4);
+ /* t1 = 7fffffffffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 55; ++i) fe448_sqr(t2, t2);
+ /* t2 = 3fffffffffffff80000000000000 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = 3fffffffffffffffffffffffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 110; ++i) fe448_sqr(t2, t2);
+ /* t2 = fffffffffffffffffffffffffffc000000000000000000000000000 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 4; ++i) fe448_sqr(t2, t2);
+ /* t2 = fffffffffffffffffffffffffffffffffffffffffffffffffffffff0 */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffd */
+ fe448_mul(t1, t3, a);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffe */
+ fe448_sqr(t1, t1); for (i = 1; i < 224; ++i) fe448_sqr(t1, t1);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffe00000000000000000000000000000000000000000000000000000000 */
+ fe448_mul(r, t3, t1);
+ /* r = fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffffffffffffffffffffffffffffffffffffffffffffffffffffd */
+}
+
+/* Scalar multiply the point by a number. r = n.a
+ * Uses Montogmery ladder and only requires the x-ordinate.
+ *
+ * r [in] Field element to hold result.
+ * n [in] Scalar as an array of bytes.
+ * a [in] Point to multiply - x-ordinate only.
+ */
+int curve448(byte* r, const byte* n, const byte* a)
+{
+ int64_t x1[8];
+ int64_t x2[8];
+ int64_t z2[8];
+ int64_t x3[8];
+ int64_t z3[8];
+ int64_t t0[8];
+ int64_t t1[8];
+ int i;
+ unsigned int swap;
+ unsigned int b;
+
+ fe448_from_bytes(x1, a);
+ fe448_1(x2);
+ fe448_0(z2);
+ fe448_copy(x3, x1);
+ fe448_1(z3);
+
+ swap = 0;
+ for (i = 447; i >= 0; --i) {
+ b = (n[i >> 3] >> (i & 7)) & 1;
+ swap ^= b;
+ fe448_cswap(x2, x3, swap);
+ fe448_cswap(z2, z3, swap);
+ swap = b;
+
+ /* Montgomery Ladder - double and add */
+ fe448_add(t0, x2, z2);
+ fe448_reduce(t0);
+ fe448_add(t1, x3, z3);
+ fe448_reduce(t1);
+ fe448_sub(x2, x2, z2);
+ fe448_sub(x3, x3, z3);
+ fe448_mul(t1, t1, x2);
+ fe448_mul(z3, x3, t0);
+ fe448_sqr(t0, t0);
+ fe448_sqr(x2, x2);
+ fe448_add(x3, z3, t1);
+ fe448_reduce(x3);
+ fe448_sqr(x3, x3);
+ fe448_sub(z3, z3, t1);
+ fe448_sqr(z3, z3);
+ fe448_mul(z3, z3, x1);
+ fe448_sub(t1, t0, x2);
+ fe448_mul(x2, t0, x2);
+ fe448_mul39081(z2, t1);
+ fe448_add(z2, t0, z2);
+ fe448_mul(z2, z2, t1);
+ }
+ /* Last two bits are 0 - no final swap check required. */
+
+ fe448_invert(z2, z2);
+ fe448_mul(x2, x2, z2);
+ fe448_to_bytes(r, x2);
+
+ return 0;
+}
+
+#ifdef HAVE_ED448
+/* Check whether field element is not 0.
+ * Must convert to a normalized form before checking.
+ *
+ * a [in] Field element.
+ * returns 0 when zero, and any other value otherwise.
+ */
+int fe448_isnonzero(const int64_t* a)
+{
+ uint8_t b[56];
+ int i;
+ uint8_t c = 0;
+ fe448_to_bytes(b, a);
+ for (i = 0; i < 56; i++)
+ c |= b[i];
+ return c;
+}
+
+/* Check whether field element is negative.
+ * Must convert to a normalized form before checking.
+ *
+ * a [in] Field element.
+ * returns 1 when negative, and 0 otherwise.
+ */
+int fe448_isnegative(const int64_t* a)
+{
+ uint8_t b[56];
+ fe448_to_bytes(b, a);
+ return b[0] & 1;
+}
+
+/* Negates the field element. r = -a
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element.
+ */
+void fe448_neg(int64_t* r, const int64_t* a)
+{
+ r[0] = -a[0];
+ r[1] = -a[1];
+ r[2] = -a[2];
+ r[3] = -a[3];
+ r[4] = -a[4];
+ r[5] = -a[5];
+ r[6] = -a[6];
+ r[7] = -a[7];
+}
+
+/* Raise field element to (p-3) / 4: 2^446 - 2^222 - 1
+ * Used for calcualting y-ordinate from x-ordinate for Ed448.
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to exponentiate.
+ */
+void fe448_pow_2_446_222_1(int64_t* r, const int64_t* a)
+{
+ int64_t t1[8];
+ int64_t t2[8];
+ int64_t t3[8];
+ int64_t t4[8];
+ int64_t t5[8];
+ int i;
+
+ fe448_sqr(t3, a);
+ /* t3 = 2 */
+ fe448_mul(t1, t3, a);
+ /* t1 = 3 */
+ fe448_sqr(t5, t1);
+ /* t5 = 6 */
+ fe448_mul(t5, t5, a);
+ /* t5 = 7 */
+ fe448_sqr(t2, t1); for (i = 1; i < 2; ++i) fe448_sqr(t2, t2);
+ /* t2 = c */
+ fe448_mul(t3, t2, t3);
+ /* t3 = e */
+ fe448_mul(t1, t2, t1);
+ /* t1 = f */
+ fe448_sqr(t2, t1); for (i = 1; i < 3; ++i) fe448_sqr(t2, t2);
+ /* t2 = 78 */
+ fe448_mul(t5, t2, t5);
+ /* t5 = 7f */
+ fe448_sqr(t2, t1); for (i = 1; i < 4; ++i) fe448_sqr(t2, t2);
+ /* t2 = f0 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = ff */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fe */
+ fe448_sqr(t2, t1); for (i = 1; i < 7; ++i) fe448_sqr(t2, t2);
+ /* t2 = 7f80 */
+ fe448_mul(t5, t2, t5);
+ /* t5 = 7fff */
+ fe448_sqr(t2, t1); for (i = 1; i < 8; ++i) fe448_sqr(t2, t2);
+ /* t2 = ff00 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = ffff */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fffe */
+ fe448_sqr(t2, t5); for (i = 1; i < 15; ++i) fe448_sqr(t2, t2);
+ /* t2 = 3fff8000 */
+ fe448_mul(t5, t2, t5);
+ /* t5 = 3fffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 16; ++i) fe448_sqr(t2, t2);
+ /* t2 = ffff0000 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = ffffffff */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fffffffe */
+ fe448_sqr(t2, t1); for (i = 1; i < 32; ++i) fe448_sqr(t2, t2);
+ /* t2 = ffffffff00000000 */
+ fe448_mul(t2, t2, t1);
+ /* t2 = ffffffffffffffff */
+ fe448_sqr(t1, t2); for (i = 1; i < 64; ++i) fe448_sqr(t1, t1);
+ /* t1 = ffffffffffffffff0000000000000000 */
+ fe448_mul(t1, t1, t2);
+ /* t1 = ffffffffffffffffffffffffffffffff */
+ fe448_sqr(t1, t1); for (i = 1; i < 64; ++i) fe448_sqr(t1, t1);
+ /* t1 = ffffffffffffffffffffffffffffffff0000000000000000 */
+ fe448_mul(t4, t1, t2);
+ /* t4 = ffffffffffffffffffffffffffffffffffffffffffffffff */
+ fe448_sqr(t2, t4); for (i = 1; i < 32; ++i) fe448_sqr(t2, t2);
+ /* t2 = ffffffffffffffffffffffffffffffffffffffffffffffff00000000 */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffe */
+ fe448_sqr(t1, t3); for (i = 1; i < 192; ++i) fe448_sqr(t1, t1);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffe000000000000000000000000000000000000000000000000 */
+ fe448_mul(t1, t1, t4);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffeffffffffffffffffffffffffffffffffffffffffffffffff */
+ fe448_sqr(t1, t1); for (i = 1; i < 30; ++i) fe448_sqr(t1, t1);
+ /* t1 = 3fffffffffffffffffffffffffffffffffffffffffffffffffffffffbfffffffffffffffffffffffffffffffffffffffffffffffc0000000 */
+ fe448_mul(r, t5, t1);
+ /* r = 3fffffffffffffffffffffffffffffffffffffffffffffffffffffffbfffffffffffffffffffffffffffffffffffffffffffffffffffffff */
+}
+
+/* Constant time, conditional move of b into a.
+ * a is not changed if the condition is 0.
+ *
+ * a A field element.
+ * b A field element.
+ * c If 1 then copy and if 0 then don't copy.
+ */
+void fe448_cmov(int64_t* a, const int64_t* b, int c)
+{
+ int64_t m = -(int64_t)c;
+ int64_t t0 = m & (a[0] ^ b[0]);
+ int64_t t1 = m & (a[1] ^ b[1]);
+ int64_t t2 = m & (a[2] ^ b[2]);
+ int64_t t3 = m & (a[3] ^ b[3]);
+ int64_t t4 = m & (a[4] ^ b[4]);
+ int64_t t5 = m & (a[5] ^ b[5]);
+ int64_t t6 = m & (a[6] ^ b[6]);
+ int64_t t7 = m & (a[7] ^ b[7]);
+
+ a[0] ^= t0;
+ a[1] ^= t1;
+ a[2] ^= t2;
+ a[3] ^= t3;
+ a[4] ^= t4;
+ a[5] ^= t5;
+ a[6] ^= t6;
+ a[7] ^= t7;
+}
+
+#endif /* HAVE_ED448 */
+#else
+
+/* Initialize the field element operations.
+ */
+void fe448_init(void)
+{
+}
+
+/* Convert the field element from a byte array to an array of 28-bits.
+ *
+ * r [in] Array to encode into.
+ * b [in] Byte array.
+ */
+void fe448_from_bytes(int32_t* r, const unsigned char* b)
+{
+ r[ 0] = (((int32_t)((b[ 0] ) >> 0)) << 0)
+ | (((int32_t)((b[ 1] ) >> 0)) << 8)
+ | (((int32_t)((b[ 2] ) >> 0)) << 16)
+ | ((((int32_t)((b[ 3] & 0xf )) >> 0)) << 24);
+ r[ 1] = (((int32_t)((b[ 3] ) >> 4)) << 0)
+ | (((int32_t)((b[ 4] ) >> 0)) << 4)
+ | (((int32_t)((b[ 5] ) >> 0)) << 12)
+ | (((int32_t)((b[ 6] ) >> 0)) << 20);
+ r[ 2] = (((int32_t)((b[ 7] ) >> 0)) << 0)
+ | (((int32_t)((b[ 8] ) >> 0)) << 8)
+ | (((int32_t)((b[ 9] ) >> 0)) << 16)
+ | ((((int32_t)((b[10] & 0xf )) >> 0)) << 24);
+ r[ 3] = (((int32_t)((b[10] ) >> 4)) << 0)
+ | (((int32_t)((b[11] ) >> 0)) << 4)
+ | (((int32_t)((b[12] ) >> 0)) << 12)
+ | (((int32_t)((b[13] ) >> 0)) << 20);
+ r[ 4] = (((int32_t)((b[14] ) >> 0)) << 0)
+ | (((int32_t)((b[15] ) >> 0)) << 8)
+ | (((int32_t)((b[16] ) >> 0)) << 16)
+ | ((((int32_t)((b[17] & 0xf )) >> 0)) << 24);
+ r[ 5] = (((int32_t)((b[17] ) >> 4)) << 0)
+ | (((int32_t)((b[18] ) >> 0)) << 4)
+ | (((int32_t)((b[19] ) >> 0)) << 12)
+ | (((int32_t)((b[20] ) >> 0)) << 20);
+ r[ 6] = (((int32_t)((b[21] ) >> 0)) << 0)
+ | (((int32_t)((b[22] ) >> 0)) << 8)
+ | (((int32_t)((b[23] ) >> 0)) << 16)
+ | ((((int32_t)((b[24] & 0xf )) >> 0)) << 24);
+ r[ 7] = (((int32_t)((b[24] ) >> 4)) << 0)
+ | (((int32_t)((b[25] ) >> 0)) << 4)
+ | (((int32_t)((b[26] ) >> 0)) << 12)
+ | (((int32_t)((b[27] ) >> 0)) << 20);
+ r[ 8] = (((int32_t)((b[28] ) >> 0)) << 0)
+ | (((int32_t)((b[29] ) >> 0)) << 8)
+ | (((int32_t)((b[30] ) >> 0)) << 16)
+ | ((((int32_t)((b[31] & 0xf )) >> 0)) << 24);
+ r[ 9] = (((int32_t)((b[31] ) >> 4)) << 0)
+ | (((int32_t)((b[32] ) >> 0)) << 4)
+ | (((int32_t)((b[33] ) >> 0)) << 12)
+ | (((int32_t)((b[34] ) >> 0)) << 20);
+ r[10] = (((int32_t)((b[35] ) >> 0)) << 0)
+ | (((int32_t)((b[36] ) >> 0)) << 8)
+ | (((int32_t)((b[37] ) >> 0)) << 16)
+ | ((((int32_t)((b[38] & 0xf )) >> 0)) << 24);
+ r[11] = (((int32_t)((b[38] ) >> 4)) << 0)
+ | (((int32_t)((b[39] ) >> 0)) << 4)
+ | (((int32_t)((b[40] ) >> 0)) << 12)
+ | (((int32_t)((b[41] ) >> 0)) << 20);
+ r[12] = (((int32_t)((b[42] ) >> 0)) << 0)
+ | (((int32_t)((b[43] ) >> 0)) << 8)
+ | (((int32_t)((b[44] ) >> 0)) << 16)
+ | ((((int32_t)((b[45] & 0xf )) >> 0)) << 24);
+ r[13] = (((int32_t)((b[45] ) >> 4)) << 0)
+ | (((int32_t)((b[46] ) >> 0)) << 4)
+ | (((int32_t)((b[47] ) >> 0)) << 12)
+ | (((int32_t)((b[48] ) >> 0)) << 20);
+ r[14] = (((int32_t)((b[49] ) >> 0)) << 0)
+ | (((int32_t)((b[50] ) >> 0)) << 8)
+ | (((int32_t)((b[51] ) >> 0)) << 16)
+ | ((((int32_t)((b[52] & 0xf )) >> 0)) << 24);
+ r[15] = (((int32_t)((b[52] ) >> 4)) << 0)
+ | (((int32_t)((b[53] ) >> 0)) << 4)
+ | (((int32_t)((b[54] ) >> 0)) << 12)
+ | (((int32_t)((b[55] ) >> 0)) << 20);
+}
+
+/* Convert the field element to a byte array from an array of 28-bits.
+ *
+ * b [in] Byte array.
+ * a [in] Array to encode into.
+ */
+void fe448_to_bytes(unsigned char* b, const int32_t* a)
+{
+ int64_t t;
+ /* Mod */
+ int32_t in0 = a[0];
+ int32_t in1 = a[1];
+ int32_t in2 = a[2];
+ int32_t in3 = a[3];
+ int32_t in4 = a[4];
+ int32_t in5 = a[5];
+ int32_t in6 = a[6];
+ int32_t in7 = a[7];
+ int32_t in8 = a[8];
+ int32_t in9 = a[9];
+ int32_t in10 = a[10];
+ int32_t in11 = a[11];
+ int32_t in12 = a[12];
+ int32_t in13 = a[13];
+ int32_t in14 = a[14];
+ int32_t in15 = a[15];
+ int32_t o = in15 >> 28;
+ in15 -= o << 28;
+ in0 += o;
+ in8 += o;
+ o = (in0 + 1) >> 28;
+ o = (o + in1) >> 28;
+ o = (o + in2) >> 28;
+ o = (o + in3) >> 28;
+ o = (o + in4) >> 28;
+ o = (o + in5) >> 28;
+ o = (o + in6) >> 28;
+ o = (o + in7) >> 28;
+ o = (o + in8 + 1) >> 28;
+ o = (o + in9) >> 28;
+ o = (o + in10) >> 28;
+ o = (o + in11) >> 28;
+ o = (o + in12) >> 28;
+ o = (o + in13) >> 28;
+ o = (o + in14) >> 28;
+ o = (o + in15) >> 28;
+ in0 += o;
+ in8 += o;
+ in15 -= o << 28;
+ o = in0 >> 28; in1 += o; t = o << 28; in0 -= t;
+ o = in1 >> 28; in2 += o; t = o << 28; in1 -= t;
+ o = in2 >> 28; in3 += o; t = o << 28; in2 -= t;
+ o = in3 >> 28; in4 += o; t = o << 28; in3 -= t;
+ o = in4 >> 28; in5 += o; t = o << 28; in4 -= t;
+ o = in5 >> 28; in6 += o; t = o << 28; in5 -= t;
+ o = in6 >> 28; in7 += o; t = o << 28; in6 -= t;
+ o = in7 >> 28; in8 += o; t = o << 28; in7 -= t;
+ o = in8 >> 28; in9 += o; t = o << 28; in8 -= t;
+ o = in9 >> 28; in10 += o; t = o << 28; in9 -= t;
+ o = in10 >> 28; in11 += o; t = o << 28; in10 -= t;
+ o = in11 >> 28; in12 += o; t = o << 28; in11 -= t;
+ o = in12 >> 28; in13 += o; t = o << 28; in12 -= t;
+ o = in13 >> 28; in14 += o; t = o << 28; in13 -= t;
+ o = in14 >> 28; in15 += o; t = o << 28; in14 -= t;
+ o = in15 >> 28; in0 += o;
+ in8 += o; t = o << 28; in15 -= t;
+
+ /* Output as bytes */
+ b[ 0] = (in0 >> 0);
+ b[ 1] = (in0 >> 8);
+ b[ 2] = (in0 >> 16);
+ b[ 3] = (in0 >> 24) + ((in1 >> 0) << 4);
+ b[ 4] = (in1 >> 4);
+ b[ 5] = (in1 >> 12);
+ b[ 6] = (in1 >> 20);
+ b[ 7] = (in2 >> 0);
+ b[ 8] = (in2 >> 8);
+ b[ 9] = (in2 >> 16);
+ b[10] = (in2 >> 24) + ((in3 >> 0) << 4);
+ b[11] = (in3 >> 4);
+ b[12] = (in3 >> 12);
+ b[13] = (in3 >> 20);
+ b[14] = (in4 >> 0);
+ b[15] = (in4 >> 8);
+ b[16] = (in4 >> 16);
+ b[17] = (in4 >> 24) + ((in5 >> 0) << 4);
+ b[18] = (in5 >> 4);
+ b[19] = (in5 >> 12);
+ b[20] = (in5 >> 20);
+ b[21] = (in6 >> 0);
+ b[22] = (in6 >> 8);
+ b[23] = (in6 >> 16);
+ b[24] = (in6 >> 24) + ((in7 >> 0) << 4);
+ b[25] = (in7 >> 4);
+ b[26] = (in7 >> 12);
+ b[27] = (in7 >> 20);
+ b[28] = (in8 >> 0);
+ b[29] = (in8 >> 8);
+ b[30] = (in8 >> 16);
+ b[31] = (in8 >> 24) + ((in9 >> 0) << 4);
+ b[32] = (in9 >> 4);
+ b[33] = (in9 >> 12);
+ b[34] = (in9 >> 20);
+ b[35] = (in10 >> 0);
+ b[36] = (in10 >> 8);
+ b[37] = (in10 >> 16);
+ b[38] = (in10 >> 24) + ((in11 >> 0) << 4);
+ b[39] = (in11 >> 4);
+ b[40] = (in11 >> 12);
+ b[41] = (in11 >> 20);
+ b[42] = (in12 >> 0);
+ b[43] = (in12 >> 8);
+ b[44] = (in12 >> 16);
+ b[45] = (in12 >> 24) + ((in13 >> 0) << 4);
+ b[46] = (in13 >> 4);
+ b[47] = (in13 >> 12);
+ b[48] = (in13 >> 20);
+ b[49] = (in14 >> 0);
+ b[50] = (in14 >> 8);
+ b[51] = (in14 >> 16);
+ b[52] = (in14 >> 24) + ((in15 >> 0) << 4);
+ b[53] = (in15 >> 4);
+ b[54] = (in15 >> 12);
+ b[55] = (in15 >> 20);
+}
+
+/* Set the field element to 0.
+ *
+ * a [in] Field element.
+ */
+void fe448_1(int32_t* a)
+{
+ a[0] = 1;
+ a[1] = 0;
+ a[2] = 0;
+ a[3] = 0;
+ a[4] = 0;
+ a[5] = 0;
+ a[6] = 0;
+ a[7] = 0;
+ a[8] = 0;
+ a[9] = 0;
+ a[10] = 0;
+ a[11] = 0;
+ a[12] = 0;
+ a[13] = 0;
+ a[14] = 0;
+ a[15] = 0;
+}
+
+/* Set the field element to 0.
+ *
+ * a [in] Field element.
+ */
+void fe448_0(int32_t* a)
+{
+ a[0] = 0;
+ a[1] = 0;
+ a[2] = 0;
+ a[3] = 0;
+ a[4] = 0;
+ a[5] = 0;
+ a[6] = 0;
+ a[7] = 0;
+ a[8] = 0;
+ a[9] = 0;
+ a[10] = 0;
+ a[11] = 0;
+ a[12] = 0;
+ a[13] = 0;
+ a[14] = 0;
+ a[15] = 0;
+}
+
+/* Copy one field element into another: d = a.
+ *
+ * d [in] Destination field element.
+ * a [in] Source field element.
+ */
+void fe448_copy(int32_t* d, const int32_t* a)
+{
+ d[0] = a[0];
+ d[1] = a[1];
+ d[2] = a[2];
+ d[3] = a[3];
+ d[4] = a[4];
+ d[5] = a[5];
+ d[6] = a[6];
+ d[7] = a[7];
+ d[8] = a[8];
+ d[9] = a[9];
+ d[10] = a[10];
+ d[11] = a[11];
+ d[12] = a[12];
+ d[13] = a[13];
+ d[14] = a[14];
+ d[15] = a[15];
+}
+
+/* Conditionally swap the elements.
+ * Constant time implementation.
+ *
+ * a [in] First field element.
+ * b [in] Second field element.
+ * c [in] Swap when 1. Valid values: 0, 1.
+ */
+static void fe448_cswap(int32_t* a, int32_t* b, int c)
+{
+ int32_t mask = -(int32_t)c;
+ int32_t t0 = (a[0] ^ b[0]) & mask;
+ int32_t t1 = (a[1] ^ b[1]) & mask;
+ int32_t t2 = (a[2] ^ b[2]) & mask;
+ int32_t t3 = (a[3] ^ b[3]) & mask;
+ int32_t t4 = (a[4] ^ b[4]) & mask;
+ int32_t t5 = (a[5] ^ b[5]) & mask;
+ int32_t t6 = (a[6] ^ b[6]) & mask;
+ int32_t t7 = (a[7] ^ b[7]) & mask;
+ int32_t t8 = (a[8] ^ b[8]) & mask;
+ int32_t t9 = (a[9] ^ b[9]) & mask;
+ int32_t t10 = (a[10] ^ b[10]) & mask;
+ int32_t t11 = (a[11] ^ b[11]) & mask;
+ int32_t t12 = (a[12] ^ b[12]) & mask;
+ int32_t t13 = (a[13] ^ b[13]) & mask;
+ int32_t t14 = (a[14] ^ b[14]) & mask;
+ int32_t t15 = (a[15] ^ b[15]) & mask;
+ a[0] ^= t0;
+ a[1] ^= t1;
+ a[2] ^= t2;
+ a[3] ^= t3;
+ a[4] ^= t4;
+ a[5] ^= t5;
+ a[6] ^= t6;
+ a[7] ^= t7;
+ a[8] ^= t8;
+ a[9] ^= t9;
+ a[10] ^= t10;
+ a[11] ^= t11;
+ a[12] ^= t12;
+ a[13] ^= t13;
+ a[14] ^= t14;
+ a[15] ^= t15;
+ b[0] ^= t0;
+ b[1] ^= t1;
+ b[2] ^= t2;
+ b[3] ^= t3;
+ b[4] ^= t4;
+ b[5] ^= t5;
+ b[6] ^= t6;
+ b[7] ^= t7;
+ b[8] ^= t8;
+ b[9] ^= t9;
+ b[10] ^= t10;
+ b[11] ^= t11;
+ b[12] ^= t12;
+ b[13] ^= t13;
+ b[14] ^= t14;
+ b[15] ^= t15;
+}
+
+/* Add two field elements. r = (a + b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold sum.
+ * a [in] Field element to add.
+ * b [in] Field element to add.
+ */
+void fe448_add(int32_t* r, const int32_t* a, const int32_t* b)
+{
+ r[0] = a[0] + b[0];
+ r[1] = a[1] + b[1];
+ r[2] = a[2] + b[2];
+ r[3] = a[3] + b[3];
+ r[4] = a[4] + b[4];
+ r[5] = a[5] + b[5];
+ r[6] = a[6] + b[6];
+ r[7] = a[7] + b[7];
+ r[8] = a[8] + b[8];
+ r[9] = a[9] + b[9];
+ r[10] = a[10] + b[10];
+ r[11] = a[11] + b[11];
+ r[12] = a[12] + b[12];
+ r[13] = a[13] + b[13];
+ r[14] = a[14] + b[14];
+ r[15] = a[15] + b[15];
+}
+
+/* Subtract a field element from another. r = (a - b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold difference.
+ * a [in] Field element to subtract from.
+ * b [in] Field element to subtract.
+ */
+void fe448_sub(int32_t* r, const int32_t* a, const int32_t* b)
+{
+ r[0] = a[0] - b[0];
+ r[1] = a[1] - b[1];
+ r[2] = a[2] - b[2];
+ r[3] = a[3] - b[3];
+ r[4] = a[4] - b[4];
+ r[5] = a[5] - b[5];
+ r[6] = a[6] - b[6];
+ r[7] = a[7] - b[7];
+ r[8] = a[8] - b[8];
+ r[9] = a[9] - b[9];
+ r[10] = a[10] - b[10];
+ r[11] = a[11] - b[11];
+ r[12] = a[12] - b[12];
+ r[13] = a[13] - b[13];
+ r[14] = a[14] - b[14];
+ r[15] = a[15] - b[15];
+}
+
+void fe448_reduce(int32_t* a)
+{
+ int64_t o;
+
+ o = a[0 ] >> 28; a[1 ] += o; a[0 ] -= o << 28;
+ o = a[1 ] >> 28; a[2 ] += o; a[1 ] -= o << 28;
+ o = a[2 ] >> 28; a[3 ] += o; a[2 ] -= o << 28;
+ o = a[3 ] >> 28; a[4 ] += o; a[3 ] -= o << 28;
+ o = a[4 ] >> 28; a[5 ] += o; a[4 ] -= o << 28;
+ o = a[5 ] >> 28; a[6 ] += o; a[5 ] -= o << 28;
+ o = a[6 ] >> 28; a[7 ] += o; a[6 ] -= o << 28;
+ o = a[7 ] >> 28; a[8 ] += o; a[7 ] -= o << 28;
+ o = a[8 ] >> 28; a[9 ] += o; a[8 ] -= o << 28;
+ o = a[9 ] >> 28; a[10] += o; a[9 ] -= o << 28;
+ o = a[10] >> 28; a[11] += o; a[10] -= o << 28;
+ o = a[11] >> 28; a[12] += o; a[11] -= o << 28;
+ o = a[12] >> 28; a[13] += o; a[12] -= o << 28;
+ o = a[13] >> 28; a[14] += o; a[13] -= o << 28;
+ o = a[14] >> 28; a[15] += o; a[14] -= o << 28;
+ o = a[15] >> 28; a[0] += o;
+ a[8] += o; a[15] -= o << 28;
+}
+/* Mulitply a field element by 39081. r = (39081 * a) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to multiply.
+ */
+void fe448_mul39081(int32_t* r, const int32_t* a)
+{
+ int64_t t;
+ int32_t o;
+ int64_t t0 = a[0] * (int64_t)39081;
+ int64_t t1 = a[1] * (int64_t)39081;
+ int64_t t2 = a[2] * (int64_t)39081;
+ int64_t t3 = a[3] * (int64_t)39081;
+ int64_t t4 = a[4] * (int64_t)39081;
+ int64_t t5 = a[5] * (int64_t)39081;
+ int64_t t6 = a[6] * (int64_t)39081;
+ int64_t t7 = a[7] * (int64_t)39081;
+ int64_t t8 = a[8] * (int64_t)39081;
+ int64_t t9 = a[9] * (int64_t)39081;
+ int64_t t10 = a[10] * (int64_t)39081;
+ int64_t t11 = a[11] * (int64_t)39081;
+ int64_t t12 = a[12] * (int64_t)39081;
+ int64_t t13 = a[13] * (int64_t)39081;
+ int64_t t14 = a[14] * (int64_t)39081;
+ int64_t t15 = a[15] * (int64_t)39081;
+ o = t0 >> 28; t1 += o; t = (int64_t)o << 28; t0 -= t;
+ o = t1 >> 28; t2 += o; t = (int64_t)o << 28; t1 -= t;
+ o = t2 >> 28; t3 += o; t = (int64_t)o << 28; t2 -= t;
+ o = t3 >> 28; t4 += o; t = (int64_t)o << 28; t3 -= t;
+ o = t4 >> 28; t5 += o; t = (int64_t)o << 28; t4 -= t;
+ o = t5 >> 28; t6 += o; t = (int64_t)o << 28; t5 -= t;
+ o = t6 >> 28; t7 += o; t = (int64_t)o << 28; t6 -= t;
+ o = t7 >> 28; t8 += o; t = (int64_t)o << 28; t7 -= t;
+ o = t8 >> 28; t9 += o; t = (int64_t)o << 28; t8 -= t;
+ o = t9 >> 28; t10 += o; t = (int64_t)o << 28; t9 -= t;
+ o = t10 >> 28; t11 += o; t = (int64_t)o << 28; t10 -= t;
+ o = t11 >> 28; t12 += o; t = (int64_t)o << 28; t11 -= t;
+ o = t12 >> 28; t13 += o; t = (int64_t)o << 28; t12 -= t;
+ o = t13 >> 28; t14 += o; t = (int64_t)o << 28; t13 -= t;
+ o = t14 >> 28; t15 += o; t = (int64_t)o << 28; t14 -= t;
+ o = t15 >> 28; t0 += o;
+ t8 += o; t = (int64_t)o << 28; t15 -= t;
+
+ /* Store */
+ r[0] = t0;
+ r[1] = t1;
+ r[2] = t2;
+ r[3] = t3;
+ r[4] = t4;
+ r[5] = t5;
+ r[6] = t6;
+ r[7] = t7;
+ r[8] = t8;
+ r[9] = t9;
+ r[10] = t10;
+ r[11] = t11;
+ r[12] = t12;
+ r[13] = t13;
+ r[14] = t14;
+ r[15] = t15;
+}
+
+/* Mulitply two field elements. r = a * b
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to multiply.
+ * b [in] Field element to multiply.
+ */
+static WC_INLINE void fe448_mul_8(int32_t* r, const int32_t* a, const int32_t* b)
+{
+ int64_t t;
+ int64_t t0 = (int64_t)a[ 0] * b[ 0];
+ int64_t t1 = (int64_t)a[ 0] * b[ 1];
+ int64_t t101 = (int64_t)a[ 1] * b[ 0];
+ int64_t t2 = (int64_t)a[ 0] * b[ 2];
+ int64_t t102 = (int64_t)a[ 1] * b[ 1];
+ int64_t t202 = (int64_t)a[ 2] * b[ 0];
+ int64_t t3 = (int64_t)a[ 0] * b[ 3];
+ int64_t t103 = (int64_t)a[ 1] * b[ 2];
+ int64_t t203 = (int64_t)a[ 2] * b[ 1];
+ int64_t t303 = (int64_t)a[ 3] * b[ 0];
+ int64_t t4 = (int64_t)a[ 0] * b[ 4];
+ int64_t t104 = (int64_t)a[ 1] * b[ 3];
+ int64_t t204 = (int64_t)a[ 2] * b[ 2];
+ int64_t t304 = (int64_t)a[ 3] * b[ 1];
+ int64_t t404 = (int64_t)a[ 4] * b[ 0];
+ int64_t t5 = (int64_t)a[ 0] * b[ 5];
+ int64_t t105 = (int64_t)a[ 1] * b[ 4];
+ int64_t t205 = (int64_t)a[ 2] * b[ 3];
+ int64_t t305 = (int64_t)a[ 3] * b[ 2];
+ int64_t t405 = (int64_t)a[ 4] * b[ 1];
+ int64_t t505 = (int64_t)a[ 5] * b[ 0];
+ int64_t t6 = (int64_t)a[ 0] * b[ 6];
+ int64_t t106 = (int64_t)a[ 1] * b[ 5];
+ int64_t t206 = (int64_t)a[ 2] * b[ 4];
+ int64_t t306 = (int64_t)a[ 3] * b[ 3];
+ int64_t t406 = (int64_t)a[ 4] * b[ 2];
+ int64_t t506 = (int64_t)a[ 5] * b[ 1];
+ int64_t t606 = (int64_t)a[ 6] * b[ 0];
+ int64_t t7 = (int64_t)a[ 0] * b[ 7];
+ int64_t t107 = (int64_t)a[ 1] * b[ 6];
+ int64_t t207 = (int64_t)a[ 2] * b[ 5];
+ int64_t t307 = (int64_t)a[ 3] * b[ 4];
+ int64_t t407 = (int64_t)a[ 4] * b[ 3];
+ int64_t t507 = (int64_t)a[ 5] * b[ 2];
+ int64_t t607 = (int64_t)a[ 6] * b[ 1];
+ int64_t t707 = (int64_t)a[ 7] * b[ 0];
+ int64_t t8 = (int64_t)a[ 1] * b[ 7];
+ int64_t t108 = (int64_t)a[ 2] * b[ 6];
+ int64_t t208 = (int64_t)a[ 3] * b[ 5];
+ int64_t t308 = (int64_t)a[ 4] * b[ 4];
+ int64_t t408 = (int64_t)a[ 5] * b[ 3];
+ int64_t t508 = (int64_t)a[ 6] * b[ 2];
+ int64_t t608 = (int64_t)a[ 7] * b[ 1];
+ int64_t t9 = (int64_t)a[ 2] * b[ 7];
+ int64_t t109 = (int64_t)a[ 3] * b[ 6];
+ int64_t t209 = (int64_t)a[ 4] * b[ 5];
+ int64_t t309 = (int64_t)a[ 5] * b[ 4];
+ int64_t t409 = (int64_t)a[ 6] * b[ 3];
+ int64_t t509 = (int64_t)a[ 7] * b[ 2];
+ int64_t t10 = (int64_t)a[ 3] * b[ 7];
+ int64_t t110 = (int64_t)a[ 4] * b[ 6];
+ int64_t t210 = (int64_t)a[ 5] * b[ 5];
+ int64_t t310 = (int64_t)a[ 6] * b[ 4];
+ int64_t t410 = (int64_t)a[ 7] * b[ 3];
+ int64_t t11 = (int64_t)a[ 4] * b[ 7];
+ int64_t t111 = (int64_t)a[ 5] * b[ 6];
+ int64_t t211 = (int64_t)a[ 6] * b[ 5];
+ int64_t t311 = (int64_t)a[ 7] * b[ 4];
+ int64_t t12 = (int64_t)a[ 5] * b[ 7];
+ int64_t t112 = (int64_t)a[ 6] * b[ 6];
+ int64_t t212 = (int64_t)a[ 7] * b[ 5];
+ int64_t t13 = (int64_t)a[ 6] * b[ 7];
+ int64_t t113 = (int64_t)a[ 7] * b[ 6];
+ int64_t t14 = (int64_t)a[ 7] * b[ 7];
+ t1 += t101;
+ t2 += t102; t2 += t202;
+ t3 += t103; t3 += t203; t3 += t303;
+ t4 += t104; t4 += t204; t4 += t304; t4 += t404;
+ t5 += t105; t5 += t205; t5 += t305; t5 += t405; t5 += t505;
+ t6 += t106; t6 += t206; t6 += t306; t6 += t406; t6 += t506;
+ t6 += t606;
+ t7 += t107; t7 += t207; t7 += t307; t7 += t407; t7 += t507;
+ t7 += t607;
+ t7 += t707;
+ t8 += t108; t8 += t208; t8 += t308; t8 += t408; t8 += t508;
+ t8 += t608;
+ t9 += t109; t9 += t209; t9 += t309; t9 += t409; t9 += t509;
+ t10 += t110; t10 += t210; t10 += t310; t10 += t410;
+ t11 += t111; t11 += t211; t11 += t311;
+ t12 += t112; t12 += t212;
+ t13 += t113;
+ int64_t o = t14 >> 28;
+ int64_t t15 = o;
+ t14 -= o << 28;
+ o = t0 >> 28; t1 += o; t = (int64_t)o << 28; t0 -= t;
+ o = t1 >> 28; t2 += o; t = (int64_t)o << 28; t1 -= t;
+ o = t2 >> 28; t3 += o; t = (int64_t)o << 28; t2 -= t;
+ o = t3 >> 28; t4 += o; t = (int64_t)o << 28; t3 -= t;
+ o = t4 >> 28; t5 += o; t = (int64_t)o << 28; t4 -= t;
+ o = t5 >> 28; t6 += o; t = (int64_t)o << 28; t5 -= t;
+ o = t6 >> 28; t7 += o; t = (int64_t)o << 28; t6 -= t;
+ o = t7 >> 28; t8 += o; t = (int64_t)o << 28; t7 -= t;
+ o = t8 >> 28; t9 += o; t = (int64_t)o << 28; t8 -= t;
+ o = t9 >> 28; t10 += o; t = (int64_t)o << 28; t9 -= t;
+ o = t10 >> 28; t11 += o; t = (int64_t)o << 28; t10 -= t;
+ o = t11 >> 28; t12 += o; t = (int64_t)o << 28; t11 -= t;
+ o = t12 >> 28; t13 += o; t = (int64_t)o << 28; t12 -= t;
+ o = t13 >> 28; t14 += o; t = (int64_t)o << 28; t13 -= t;
+ o = t14 >> 28; t15 += o; t = (int64_t)o << 28; t14 -= t;
+ o = t15 >> 28; t0 += o;
+ t8 += o; t = (int64_t)o << 28; t15 -= t;
+
+ /* Store */
+ r[0] = t0;
+ r[1] = t1;
+ r[2] = t2;
+ r[3] = t3;
+ r[4] = t4;
+ r[5] = t5;
+ r[6] = t6;
+ r[7] = t7;
+ r[8] = t8;
+ r[9] = t9;
+ r[10] = t10;
+ r[11] = t11;
+ r[12] = t12;
+ r[13] = t13;
+ r[14] = t14;
+ r[15] = t15;
+}
+
+/* Mulitply two field elements. r = (a * b) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to multiply.
+ * b [in] Field element to multiply.
+ */
+void fe448_mul(int32_t* r, const int32_t* a, const int32_t* b)
+{
+ int32_t r0[16];
+ int32_t r1[16];
+ int32_t* a1 = r1;
+ int32_t b1[8];
+ int32_t r2[16];
+ a1[0] = a[0] + a[8];
+ a1[1] = a[1] + a[9];
+ a1[2] = a[2] + a[10];
+ a1[3] = a[3] + a[11];
+ a1[4] = a[4] + a[12];
+ a1[5] = a[5] + a[13];
+ a1[6] = a[6] + a[14];
+ a1[7] = a[7] + a[15];
+ b1[0] = b[0] + b[8];
+ b1[1] = b[1] + b[9];
+ b1[2] = b[2] + b[10];
+ b1[3] = b[3] + b[11];
+ b1[4] = b[4] + b[12];
+ b1[5] = b[5] + b[13];
+ b1[6] = b[6] + b[14];
+ b1[7] = b[7] + b[15];
+ fe448_mul_8(r2, a + 8, b + 8);
+ fe448_mul_8(r0, a, b);
+ fe448_mul_8(r1, a1, b1);
+ r[ 0] = r0[ 0] + r2[ 0] + r1[ 8] - r0[ 8];
+ r[ 1] = r0[ 1] + r2[ 1] + r1[ 9] - r0[ 9];
+ r[ 2] = r0[ 2] + r2[ 2] + r1[10] - r0[10];
+ r[ 3] = r0[ 3] + r2[ 3] + r1[11] - r0[11];
+ r[ 4] = r0[ 4] + r2[ 4] + r1[12] - r0[12];
+ r[ 5] = r0[ 5] + r2[ 5] + r1[13] - r0[13];
+ r[ 6] = r0[ 6] + r2[ 6] + r1[14] - r0[14];
+ r[ 7] = r0[ 7] + r2[ 7] + r1[15] - r0[15];
+ r[ 8] = r2[ 8] + r1[ 0] - r0[ 0] + r1[ 8];
+ r[ 9] = r2[ 9] + r1[ 1] - r0[ 1] + r1[ 9];
+ r[10] = r2[10] + r1[ 2] - r0[ 2] + r1[10];
+ r[11] = r2[11] + r1[ 3] - r0[ 3] + r1[11];
+ r[12] = r2[12] + r1[ 4] - r0[ 4] + r1[12];
+ r[13] = r2[13] + r1[ 5] - r0[ 5] + r1[13];
+ r[14] = r2[14] + r1[ 6] - r0[ 6] + r1[14];
+ r[15] = r2[15] + r1[ 7] - r0[ 7] + r1[15];
+}
+
+/* Square a field element. r = a * a
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to square.
+ */
+static WC_INLINE void fe448_sqr_8(int32_t* r, const int32_t* a)
+{
+ int64_t t;
+ int64_t t0 = (int64_t)a[ 0] * a[ 0];
+ int64_t t1 = 2 * (int64_t)a[ 0] * a[ 1];
+ int64_t t2 = 2 * (int64_t)a[ 0] * a[ 2];
+ int64_t t102 = (int64_t)a[ 1] * a[ 1];
+ int64_t t3 = 2 * (int64_t)a[ 0] * a[ 3];
+ int64_t t103 = 2 * (int64_t)a[ 1] * a[ 2];
+ int64_t t4 = 2 * (int64_t)a[ 0] * a[ 4];
+ int64_t t104 = 2 * (int64_t)a[ 1] * a[ 3];
+ int64_t t204 = (int64_t)a[ 2] * a[ 2];
+ int64_t t5 = 2 * (int64_t)a[ 0] * a[ 5];
+ int64_t t105 = 2 * (int64_t)a[ 1] * a[ 4];
+ int64_t t205 = 2 * (int64_t)a[ 2] * a[ 3];
+ int64_t t6 = 2 * (int64_t)a[ 0] * a[ 6];
+ int64_t t106 = 2 * (int64_t)a[ 1] * a[ 5];
+ int64_t t206 = 2 * (int64_t)a[ 2] * a[ 4];
+ int64_t t306 = (int64_t)a[ 3] * a[ 3];
+ int64_t t7 = 2 * (int64_t)a[ 0] * a[ 7];
+ int64_t t107 = 2 * (int64_t)a[ 1] * a[ 6];
+ int64_t t207 = 2 * (int64_t)a[ 2] * a[ 5];
+ int64_t t307 = 2 * (int64_t)a[ 3] * a[ 4];
+ int64_t t8 = 2 * (int64_t)a[ 1] * a[ 7];
+ int64_t t108 = 2 * (int64_t)a[ 2] * a[ 6];
+ int64_t t208 = 2 * (int64_t)a[ 3] * a[ 5];
+ int64_t t308 = (int64_t)a[ 4] * a[ 4];
+ int64_t t9 = 2 * (int64_t)a[ 2] * a[ 7];
+ int64_t t109 = 2 * (int64_t)a[ 3] * a[ 6];
+ int64_t t209 = 2 * (int64_t)a[ 4] * a[ 5];
+ int64_t t10 = 2 * (int64_t)a[ 3] * a[ 7];
+ int64_t t110 = 2 * (int64_t)a[ 4] * a[ 6];
+ int64_t t210 = (int64_t)a[ 5] * a[ 5];
+ int64_t t11 = 2 * (int64_t)a[ 4] * a[ 7];
+ int64_t t111 = 2 * (int64_t)a[ 5] * a[ 6];
+ int64_t t12 = 2 * (int64_t)a[ 5] * a[ 7];
+ int64_t t112 = (int64_t)a[ 6] * a[ 6];
+ int64_t t13 = 2 * (int64_t)a[ 6] * a[ 7];
+ int64_t t14 = (int64_t)a[ 7] * a[ 7];
+ t2 += t102;
+ t3 += t103;
+ t4 += t104; t4 += t204;
+ t5 += t105; t5 += t205;
+ t6 += t106; t6 += t206; t6 += t306;
+ t7 += t107; t7 += t207; t7 += t307;
+ t8 += t108; t8 += t208; t8 += t308;
+ t9 += t109; t9 += t209;
+ t10 += t110; t10 += t210;
+ t11 += t111;
+ t12 += t112;
+ int64_t o = t14 >> 28;
+ int64_t t15 = o;
+ t14 -= o << 28;
+ o = t0 >> 28; t1 += o; t = (int64_t)o << 28; t0 -= t;
+ o = t1 >> 28; t2 += o; t = (int64_t)o << 28; t1 -= t;
+ o = t2 >> 28; t3 += o; t = (int64_t)o << 28; t2 -= t;
+ o = t3 >> 28; t4 += o; t = (int64_t)o << 28; t3 -= t;
+ o = t4 >> 28; t5 += o; t = (int64_t)o << 28; t4 -= t;
+ o = t5 >> 28; t6 += o; t = (int64_t)o << 28; t5 -= t;
+ o = t6 >> 28; t7 += o; t = (int64_t)o << 28; t6 -= t;
+ o = t7 >> 28; t8 += o; t = (int64_t)o << 28; t7 -= t;
+ o = t8 >> 28; t9 += o; t = (int64_t)o << 28; t8 -= t;
+ o = t9 >> 28; t10 += o; t = (int64_t)o << 28; t9 -= t;
+ o = t10 >> 28; t11 += o; t = (int64_t)o << 28; t10 -= t;
+ o = t11 >> 28; t12 += o; t = (int64_t)o << 28; t11 -= t;
+ o = t12 >> 28; t13 += o; t = (int64_t)o << 28; t12 -= t;
+ o = t13 >> 28; t14 += o; t = (int64_t)o << 28; t13 -= t;
+ o = t14 >> 28; t15 += o; t = (int64_t)o << 28; t14 -= t;
+ o = t15 >> 28; t0 += o;
+ t8 += o; t = (int64_t)o << 28; t15 -= t;
+
+ /* Store */
+ r[0] = t0;
+ r[1] = t1;
+ r[2] = t2;
+ r[3] = t3;
+ r[4] = t4;
+ r[5] = t5;
+ r[6] = t6;
+ r[7] = t7;
+ r[8] = t8;
+ r[9] = t9;
+ r[10] = t10;
+ r[11] = t11;
+ r[12] = t12;
+ r[13] = t13;
+ r[14] = t14;
+ r[15] = t15;
+}
+
+/* Square a field element. r = (a * a) mod (2^448 - 2^224 - 1)
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to square.
+ */
+void fe448_sqr(int32_t* r, const int32_t* a)
+{
+ int32_t r0[16];
+ int32_t r1[16];
+ int32_t* a1 = r1;
+ int32_t r2[16];
+ a1[0] = a[0] + a[8];
+ a1[1] = a[1] + a[9];
+ a1[2] = a[2] + a[10];
+ a1[3] = a[3] + a[11];
+ a1[4] = a[4] + a[12];
+ a1[5] = a[5] + a[13];
+ a1[6] = a[6] + a[14];
+ a1[7] = a[7] + a[15];
+ fe448_sqr_8(r2, a + 8);
+ fe448_sqr_8(r0, a);
+ fe448_sqr_8(r1, a1);
+ r[ 0] = r0[ 0] + r2[ 0] + r1[ 8] - r0[ 8];
+ r[ 1] = r0[ 1] + r2[ 1] + r1[ 9] - r0[ 9];
+ r[ 2] = r0[ 2] + r2[ 2] + r1[10] - r0[10];
+ r[ 3] = r0[ 3] + r2[ 3] + r1[11] - r0[11];
+ r[ 4] = r0[ 4] + r2[ 4] + r1[12] - r0[12];
+ r[ 5] = r0[ 5] + r2[ 5] + r1[13] - r0[13];
+ r[ 6] = r0[ 6] + r2[ 6] + r1[14] - r0[14];
+ r[ 7] = r0[ 7] + r2[ 7] + r1[15] - r0[15];
+ r[ 8] = r2[ 8] + r1[ 0] - r0[ 0] + r1[ 8];
+ r[ 9] = r2[ 9] + r1[ 1] - r0[ 1] + r1[ 9];
+ r[10] = r2[10] + r1[ 2] - r0[ 2] + r1[10];
+ r[11] = r2[11] + r1[ 3] - r0[ 3] + r1[11];
+ r[12] = r2[12] + r1[ 4] - r0[ 4] + r1[12];
+ r[13] = r2[13] + r1[ 5] - r0[ 5] + r1[13];
+ r[14] = r2[14] + r1[ 6] - r0[ 6] + r1[14];
+ r[15] = r2[15] + r1[ 7] - r0[ 7] + r1[15];
+}
+
+/* Invert the field element. (r * a) mod (2^448 - 2^224 - 1) = 1
+ * Constant time implementation - using Fermat's little theorem:
+ * a^(p-1) mod p = 1 => a^(p-2) mod p = 1/a
+ * For curve448: p - 2 = 2^448 - 2^224 - 3
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to invert.
+ */
+void fe448_invert(int32_t* r, const int32_t* a)
+{
+ int32_t t1[16];
+ int32_t t2[16];
+ int32_t t3[16];
+ int32_t t4[16];
+ int i;
+
+ fe448_sqr(t1, a);
+ /* t1 = 2 */
+ fe448_mul(t1, t1, a);
+ /* t1 = 3 */
+ fe448_sqr(t2, t1); for (i = 1; i < 2; ++i) fe448_sqr(t2, t2);
+ /* t2 = c */
+ fe448_mul(t3, t2, a);
+ /* t3 = d */
+ fe448_mul(t1, t2, t1);
+ /* t1 = f */
+ fe448_sqr(t2, t1);
+ /* t2 = 1e */
+ fe448_mul(t4, t2, a);
+ /* t4 = 1f */
+ fe448_sqr(t2, t4); for (i = 1; i < 5; ++i) fe448_sqr(t2, t2);
+ /* t2 = 3e0 */
+ fe448_mul(t1, t2, t4);
+ /* t1 = 3ff */
+ fe448_sqr(t2, t1); for (i = 1; i < 10; ++i) fe448_sqr(t2, t2);
+ /* t2 = ffc00 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = fffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 5; ++i) fe448_sqr(t2, t2);
+ /* t2 = 1ffffe0 */
+ fe448_mul(t1, t2, t4);
+ /* t1 = 1ffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 25; ++i) fe448_sqr(t2, t2);
+ /* t2 = 3fffffe000000 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = 3ffffffffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 5; ++i) fe448_sqr(t2, t2);
+ /* t2 = 7fffffffffffe0 */
+ fe448_mul(t1, t2, t4);
+ /* t1 = 7fffffffffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 55; ++i) fe448_sqr(t2, t2);
+ /* t2 = 3fffffffffffff80000000000000 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = 3fffffffffffffffffffffffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 110; ++i) fe448_sqr(t2, t2);
+ /* t2 = fffffffffffffffffffffffffffc000000000000000000000000000 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 4; ++i) fe448_sqr(t2, t2);
+ /* t2 = fffffffffffffffffffffffffffffffffffffffffffffffffffffff0 */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffd */
+ fe448_mul(t1, t3, a);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffe */
+ fe448_sqr(t1, t1); for (i = 1; i < 224; ++i) fe448_sqr(t1, t1);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffe00000000000000000000000000000000000000000000000000000000 */
+ fe448_mul(r, t3, t1);
+ /* r = fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffffffffffffffffffffffffffffffffffffffffffffffffffffd */
+}
+
+/* Scalar multiply the point by a number. r = n.a
+ * Uses Montogmery ladder and only requires the x-ordinate.
+ *
+ * r [in] Field element to hold result.
+ * n [in] Scalar as an array of bytes.
+ * a [in] Point to multiply - x-ordinate only.
+ */
+int curve448(byte* r, const byte* n, const byte* a)
+{
+ int32_t x1[16];
+ int32_t x2[16];
+ int32_t z2[16];
+ int32_t x3[16];
+ int32_t z3[16];
+ int32_t t0[16];
+ int32_t t1[16];
+ int i;
+ unsigned int swap;
+ unsigned int b;
+
+ fe448_from_bytes(x1, a);
+ fe448_1(x2);
+ fe448_0(z2);
+ fe448_copy(x3, x1);
+ fe448_1(z3);
+
+ swap = 0;
+ for (i = 447; i >= 0; --i) {
+ b = (n[i >> 3] >> (i & 7)) & 1;
+ swap ^= b;
+ fe448_cswap(x2, x3, swap);
+ fe448_cswap(z2, z3, swap);
+ swap = b;
+
+ /* Montgomery Ladder - double and add */
+ fe448_add(t0, x2, z2);
+ fe448_reduce(t0);
+ fe448_add(t1, x3, z3);
+ fe448_reduce(t1);
+ fe448_sub(x2, x2, z2);
+ fe448_sub(x3, x3, z3);
+ fe448_mul(t1, t1, x2);
+ fe448_mul(z3, x3, t0);
+ fe448_sqr(t0, t0);
+ fe448_sqr(x2, x2);
+ fe448_add(x3, z3, t1);
+ fe448_reduce(x3);
+ fe448_sqr(x3, x3);
+ fe448_sub(z3, z3, t1);
+ fe448_sqr(z3, z3);
+ fe448_mul(z3, z3, x1);
+ fe448_sub(t1, t0, x2);
+ fe448_mul(x2, t0, x2);
+ fe448_mul39081(z2, t1);
+ fe448_add(z2, t0, z2);
+ fe448_mul(z2, z2, t1);
+ }
+ /* Last two bits are 0 - no final swap check required. */
+
+ fe448_invert(z2, z2);
+ fe448_mul(x2, x2, z2);
+ fe448_to_bytes(r, x2);
+
+ return 0;
+}
+
+#ifdef HAVE_ED448
+/* Check whether field element is not 0.
+ * Must convert to a normalized form before checking.
+ *
+ * a [in] Field element.
+ * returns 0 when zero, and any other value otherwise.
+ */
+int fe448_isnonzero(const int32_t* a)
+{
+ uint8_t b[56];
+ int i;
+ uint8_t c = 0;
+ fe448_to_bytes(b, a);
+ for (i = 0; i < 56; i++)
+ c |= b[i];
+ return c;
+}
+
+/* Check whether field element is negative.
+ * Must convert to a normalized form before checking.
+ *
+ * a [in] Field element.
+ * returns 1 when negative, and 0 otherwise.
+ */
+int fe448_isnegative(const int32_t* a)
+{
+ uint8_t b[56];
+ fe448_to_bytes(b, a);
+ return b[0] & 1;
+}
+
+/* Negates the field element. r = -a
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element.
+ */
+void fe448_neg(int32_t* r, const int32_t* a)
+{
+ r[0] = -a[0];
+ r[1] = -a[1];
+ r[2] = -a[2];
+ r[3] = -a[3];
+ r[4] = -a[4];
+ r[5] = -a[5];
+ r[6] = -a[6];
+ r[7] = -a[7];
+ r[8] = -a[8];
+ r[9] = -a[9];
+ r[10] = -a[10];
+ r[11] = -a[11];
+ r[12] = -a[12];
+ r[13] = -a[13];
+ r[14] = -a[14];
+ r[15] = -a[15];
+}
+
+/* Raise field element to (p-3) / 4: 2^446 - 2^222 - 1
+ * Used for calcualting y-ordinate from x-ordinate for Ed448.
+ *
+ * r [in] Field element to hold result.
+ * a [in] Field element to exponentiate.
+ */
+void fe448_pow_2_446_222_1(int32_t* r, const int32_t* a)
+{
+ int32_t t1[16];
+ int32_t t2[16];
+ int32_t t3[16];
+ int32_t t4[16];
+ int32_t t5[16];
+ int i;
+
+ fe448_sqr(t3, a);
+ /* t3 = 2 */
+ fe448_mul(t1, t3, a);
+ /* t1 = 3 */
+ fe448_sqr(t5, t1);
+ /* t5 = 6 */
+ fe448_mul(t5, t5, a);
+ /* t5 = 7 */
+ fe448_sqr(t2, t1); for (i = 1; i < 2; ++i) fe448_sqr(t2, t2);
+ /* t2 = c */
+ fe448_mul(t3, t2, t3);
+ /* t3 = e */
+ fe448_mul(t1, t2, t1);
+ /* t1 = f */
+ fe448_sqr(t2, t1); for (i = 1; i < 3; ++i) fe448_sqr(t2, t2);
+ /* t2 = 78 */
+ fe448_mul(t5, t2, t5);
+ /* t5 = 7f */
+ fe448_sqr(t2, t1); for (i = 1; i < 4; ++i) fe448_sqr(t2, t2);
+ /* t2 = f0 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = ff */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fe */
+ fe448_sqr(t2, t1); for (i = 1; i < 7; ++i) fe448_sqr(t2, t2);
+ /* t2 = 7f80 */
+ fe448_mul(t5, t2, t5);
+ /* t5 = 7fff */
+ fe448_sqr(t2, t1); for (i = 1; i < 8; ++i) fe448_sqr(t2, t2);
+ /* t2 = ff00 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = ffff */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fffe */
+ fe448_sqr(t2, t5); for (i = 1; i < 15; ++i) fe448_sqr(t2, t2);
+ /* t2 = 3fff8000 */
+ fe448_mul(t5, t2, t5);
+ /* t5 = 3fffffff */
+ fe448_sqr(t2, t1); for (i = 1; i < 16; ++i) fe448_sqr(t2, t2);
+ /* t2 = ffff0000 */
+ fe448_mul(t1, t2, t1);
+ /* t1 = ffffffff */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fffffffe */
+ fe448_sqr(t2, t1); for (i = 1; i < 32; ++i) fe448_sqr(t2, t2);
+ /* t2 = ffffffff00000000 */
+ fe448_mul(t2, t2, t1);
+ /* t2 = ffffffffffffffff */
+ fe448_sqr(t1, t2); for (i = 1; i < 64; ++i) fe448_sqr(t1, t1);
+ /* t1 = ffffffffffffffff0000000000000000 */
+ fe448_mul(t1, t1, t2);
+ /* t1 = ffffffffffffffffffffffffffffffff */
+ fe448_sqr(t1, t1); for (i = 1; i < 64; ++i) fe448_sqr(t1, t1);
+ /* t1 = ffffffffffffffffffffffffffffffff0000000000000000 */
+ fe448_mul(t4, t1, t2);
+ /* t4 = ffffffffffffffffffffffffffffffffffffffffffffffff */
+ fe448_sqr(t2, t4); for (i = 1; i < 32; ++i) fe448_sqr(t2, t2);
+ /* t2 = ffffffffffffffffffffffffffffffffffffffffffffffff00000000 */
+ fe448_mul(t3, t3, t2);
+ /* t3 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffe */
+ fe448_sqr(t1, t3); for (i = 1; i < 192; ++i) fe448_sqr(t1, t1);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffe000000000000000000000000000000000000000000000000 */
+ fe448_mul(t1, t1, t4);
+ /* t1 = fffffffffffffffffffffffffffffffffffffffffffffffffffffffeffffffffffffffffffffffffffffffffffffffffffffffff */
+ fe448_sqr(t1, t1); for (i = 1; i < 30; ++i) fe448_sqr(t1, t1);
+ /* t1 = 3fffffffffffffffffffffffffffffffffffffffffffffffffffffffbfffffffffffffffffffffffffffffffffffffffffffffffc0000000 */
+ fe448_mul(r, t5, t1);
+ /* r = 3fffffffffffffffffffffffffffffffffffffffffffffffffffffffbfffffffffffffffffffffffffffffffffffffffffffffffffffffff */
+}
+
+/* Constant time, conditional move of b into a.
+ * a is not changed if the condition is 0.
+ *
+ * a A field element.
+ * b A field element.
+ * c If 1 then copy and if 0 then don't copy.
+ */
+void fe448_cmov(int32_t* a, const int32_t* b, int c)
+{
+ int32_t m = -(int32_t)c;
+ int32_t t0 = m & (a[0] ^ b[0]);
+ int32_t t1 = m & (a[1] ^ b[1]);
+ int32_t t2 = m & (a[2] ^ b[2]);
+ int32_t t3 = m & (a[3] ^ b[3]);
+ int32_t t4 = m & (a[4] ^ b[4]);
+ int32_t t5 = m & (a[5] ^ b[5]);
+ int32_t t6 = m & (a[6] ^ b[6]);
+ int32_t t7 = m & (a[7] ^ b[7]);
+ int32_t t8 = m & (a[8] ^ b[8]);
+ int32_t t9 = m & (a[9] ^ b[9]);
+ int32_t t10 = m & (a[10] ^ b[10]);
+ int32_t t11 = m & (a[11] ^ b[11]);
+ int32_t t12 = m & (a[12] ^ b[12]);
+ int32_t t13 = m & (a[13] ^ b[13]);
+ int32_t t14 = m & (a[14] ^ b[14]);
+ int32_t t15 = m & (a[15] ^ b[15]);
+
+ a[0] ^= t0;
+ a[1] ^= t1;
+ a[2] ^= t2;
+ a[3] ^= t3;
+ a[4] ^= t4;
+ a[5] ^= t5;
+ a[6] ^= t6;
+ a[7] ^= t7;
+ a[8] ^= t8;
+ a[9] ^= t9;
+ a[10] ^= t10;
+ a[11] ^= t11;
+ a[12] ^= t12;
+ a[13] ^= t13;
+ a[14] ^= t14;
+ a[15] ^= t15;
+}
+
+#endif /* HAVE_ED448 */
+#endif
+
+#endif /* HAVE_CURVE448 || HAVE_ED448 */
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