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-rw-r--r--security/nss/lib/freebl/ecl/curve25519_32.c390
1 files changed, 390 insertions, 0 deletions
diff --git a/security/nss/lib/freebl/ecl/curve25519_32.c b/security/nss/lib/freebl/ecl/curve25519_32.c
new file mode 100644
index 000000000..0122961e6
--- /dev/null
+++ b/security/nss/lib/freebl/ecl/curve25519_32.c
@@ -0,0 +1,390 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Derived from public domain code by Matthew Dempsky and D. J. Bernstein.
+ */
+
+#include "ecl-priv.h"
+#include "mpi.h"
+
+#include <stdint.h>
+#include <stdio.h>
+
+typedef uint32_t elem[32];
+
+/*
+ * Add two field elements.
+ * out = a + b
+ */
+static void
+add(elem out, const elem a, const elem b)
+{
+ uint32_t j;
+ uint32_t u = 0;
+ for (j = 0; j < 31; ++j) {
+ u += a[j] + b[j];
+ out[j] = u & 0xFF;
+ u >>= 8;
+ }
+ u += a[31] + b[31];
+ out[31] = u;
+}
+
+/*
+ * Subtract two field elements.
+ * out = a - b
+ */
+static void
+sub(elem out, const elem a, const elem b)
+{
+ uint32_t j;
+ uint32_t u;
+ u = 218;
+ for (j = 0; j < 31; ++j) {
+ u += a[j] + 0xFF00 - b[j];
+ out[j] = u & 0xFF;
+ u >>= 8;
+ }
+ u += a[31] - b[31];
+ out[31] = u;
+}
+
+/*
+ * "Squeeze" an element after multiplication (and square).
+ */
+static void
+squeeze(elem a)
+{
+ uint32_t j;
+ uint32_t u;
+ u = 0;
+ for (j = 0; j < 31; ++j) {
+ u += a[j];
+ a[j] = u & 0xFF;
+ u >>= 8;
+ }
+ u += a[31];
+ a[31] = u & 0x7F;
+ u = 19 * (u >> 7);
+ for (j = 0; j < 31; ++j) {
+ u += a[j];
+ a[j] = u & 0xFF;
+ u >>= 8;
+ }
+ a[31] += u;
+}
+
+static const elem minusp = { 19, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 128 };
+
+/*
+ * Reduce point a by 2^255-19
+ */
+static void
+reduce(elem a)
+{
+ elem aorig;
+ uint32_t j;
+ uint32_t negative;
+
+ for (j = 0; j < 32; ++j) {
+ aorig[j] = a[j];
+ }
+ add(a, a, minusp);
+ negative = 1 + ~((a[31] >> 7) & 1);
+ for (j = 0; j < 32; ++j) {
+ a[j] ^= negative & (aorig[j] ^ a[j]);
+ }
+}
+
+/*
+ * Multiplication and squeeze
+ * out = a * b
+ */
+static void
+mult(elem out, const elem a, const elem b)
+{
+ uint32_t i;
+ uint32_t j;
+ uint32_t u;
+
+ for (i = 0; i < 32; ++i) {
+ u = 0;
+ for (j = 0; j <= i; ++j) {
+ u += a[j] * b[i - j];
+ }
+ for (j = i + 1; j < 32; ++j) {
+ u += 38 * a[j] * b[i + 32 - j];
+ }
+ out[i] = u;
+ }
+ squeeze(out);
+}
+
+/*
+ * Multiplication
+ * out = 121665 * a
+ */
+static void
+mult121665(elem out, const elem a)
+{
+ uint32_t j;
+ uint32_t u;
+
+ u = 0;
+ for (j = 0; j < 31; ++j) {
+ u += 121665 * a[j];
+ out[j] = u & 0xFF;
+ u >>= 8;
+ }
+ u += 121665 * a[31];
+ out[31] = u & 0x7F;
+ u = 19 * (u >> 7);
+ for (j = 0; j < 31; ++j) {
+ u += out[j];
+ out[j] = u & 0xFF;
+ u >>= 8;
+ }
+ u += out[j];
+ out[j] = u;
+}
+
+/*
+ * Square a and squeeze the result.
+ * out = a * a
+ */
+static void
+square(elem out, const elem a)
+{
+ uint32_t i;
+ uint32_t j;
+ uint32_t u;
+
+ for (i = 0; i < 32; ++i) {
+ u = 0;
+ for (j = 0; j < i - j; ++j) {
+ u += a[j] * a[i - j];
+ }
+ for (j = i + 1; j < i + 32 - j; ++j) {
+ u += 38 * a[j] * a[i + 32 - j];
+ }
+ u *= 2;
+ if ((i & 1) == 0) {
+ u += a[i / 2] * a[i / 2];
+ u += 38 * a[i / 2 + 16] * a[i / 2 + 16];
+ }
+ out[i] = u;
+ }
+ squeeze(out);
+}
+
+/*
+ * Constant time swap between r and s depending on b
+ */
+static void
+cswap(uint32_t p[64], uint32_t q[64], uint32_t b)
+{
+ uint32_t j;
+ uint32_t swap = 1 + ~b;
+
+ for (j = 0; j < 64; ++j) {
+ const uint32_t t = swap & (p[j] ^ q[j]);
+ p[j] ^= t;
+ q[j] ^= t;
+ }
+}
+
+/*
+ * Montgomery ladder
+ */
+static void
+monty(elem x_2_out, elem z_2_out,
+ const elem point, const elem scalar)
+{
+ uint32_t x_3[64] = { 0 };
+ uint32_t x_2[64] = { 0 };
+ uint32_t a0[64];
+ uint32_t a1[64];
+ uint32_t b0[64];
+ uint32_t b1[64];
+ uint32_t c1[64];
+ uint32_t r[32];
+ uint32_t s[32];
+ uint32_t t[32];
+ uint32_t u[32];
+ uint32_t swap = 0;
+ uint32_t k_t = 0;
+ int j;
+
+ for (j = 0; j < 32; ++j) {
+ x_3[j] = point[j];
+ }
+ x_3[32] = 1;
+ x_2[0] = 1;
+
+ for (j = 254; j >= 0; --j) {
+ k_t = (scalar[j >> 3] >> (j & 7)) & 1;
+ swap ^= k_t;
+ cswap(x_2, x_3, swap);
+ swap = k_t;
+ add(a0, x_2, x_2 + 32);
+ sub(a0 + 32, x_2, x_2 + 32);
+ add(a1, x_3, x_3 + 32);
+ sub(a1 + 32, x_3, x_3 + 32);
+ square(b0, a0);
+ square(b0 + 32, a0 + 32);
+ mult(b1, a1, a0 + 32);
+ mult(b1 + 32, a1 + 32, a0);
+ add(c1, b1, b1 + 32);
+ sub(c1 + 32, b1, b1 + 32);
+ square(r, c1 + 32);
+ sub(s, b0, b0 + 32);
+ mult121665(t, s);
+ add(u, t, b0);
+ mult(x_2, b0, b0 + 32);
+ mult(x_2 + 32, s, u);
+ square(x_3, c1);
+ mult(x_3 + 32, r, point);
+ }
+
+ cswap(x_2, x_3, swap);
+ for (j = 0; j < 32; ++j) {
+ x_2_out[j] = x_2[j];
+ }
+ for (j = 0; j < 32; ++j) {
+ z_2_out[j] = x_2[j + 32];
+ }
+}
+
+static void
+recip(elem out, const elem z)
+{
+ elem z2;
+ elem z9;
+ elem z11;
+ elem z2_5_0;
+ elem z2_10_0;
+ elem z2_20_0;
+ elem z2_50_0;
+ elem z2_100_0;
+ elem t0;
+ elem t1;
+ int i;
+
+ /* 2 */ square(z2, z);
+ /* 4 */ square(t1, z2);
+ /* 8 */ square(t0, t1);
+ /* 9 */ mult(z9, t0, z);
+ /* 11 */ mult(z11, z9, z2);
+ /* 22 */ square(t0, z11);
+ /* 2^5 - 2^0 = 31 */ mult(z2_5_0, t0, z9);
+
+ /* 2^6 - 2^1 */ square(t0, z2_5_0);
+ /* 2^7 - 2^2 */ square(t1, t0);
+ /* 2^8 - 2^3 */ square(t0, t1);
+ /* 2^9 - 2^4 */ square(t1, t0);
+ /* 2^10 - 2^5 */ square(t0, t1);
+ /* 2^10 - 2^0 */ mult(z2_10_0, t0, z2_5_0);
+
+ /* 2^11 - 2^1 */ square(t0, z2_10_0);
+ /* 2^12 - 2^2 */ square(t1, t0);
+ /* 2^20 - 2^10 */
+ for (i = 2; i < 10; i += 2) {
+ square(t0, t1);
+ square(t1, t0);
+ }
+ /* 2^20 - 2^0 */ mult(z2_20_0, t1, z2_10_0);
+
+ /* 2^21 - 2^1 */ square(t0, z2_20_0);
+ /* 2^22 - 2^2 */ square(t1, t0);
+ /* 2^40 - 2^20 */
+ for (i = 2; i < 20; i += 2) {
+ square(t0, t1);
+ square(t1, t0);
+ }
+ /* 2^40 - 2^0 */ mult(t0, t1, z2_20_0);
+
+ /* 2^41 - 2^1 */ square(t1, t0);
+ /* 2^42 - 2^2 */ square(t0, t1);
+ /* 2^50 - 2^10 */
+ for (i = 2; i < 10; i += 2) {
+ square(t1, t0);
+ square(t0, t1);
+ }
+ /* 2^50 - 2^0 */ mult(z2_50_0, t0, z2_10_0);
+
+ /* 2^51 - 2^1 */ square(t0, z2_50_0);
+ /* 2^52 - 2^2 */ square(t1, t0);
+ /* 2^100 - 2^50 */
+ for (i = 2; i < 50; i += 2) {
+ square(t0, t1);
+ square(t1, t0);
+ }
+ /* 2^100 - 2^0 */ mult(z2_100_0, t1, z2_50_0);
+
+ /* 2^101 - 2^1 */ square(t1, z2_100_0);
+ /* 2^102 - 2^2 */ square(t0, t1);
+ /* 2^200 - 2^100 */
+ for (i = 2; i < 100; i += 2) {
+ square(t1, t0);
+ square(t0, t1);
+ }
+ /* 2^200 - 2^0 */ mult(t1, t0, z2_100_0);
+
+ /* 2^201 - 2^1 */ square(t0, t1);
+ /* 2^202 - 2^2 */ square(t1, t0);
+ /* 2^250 - 2^50 */
+ for (i = 2; i < 50; i += 2) {
+ square(t0, t1);
+ square(t1, t0);
+ }
+ /* 2^250 - 2^0 */ mult(t0, t1, z2_50_0);
+
+ /* 2^251 - 2^1 */ square(t1, t0);
+ /* 2^252 - 2^2 */ square(t0, t1);
+ /* 2^253 - 2^3 */ square(t1, t0);
+ /* 2^254 - 2^4 */ square(t0, t1);
+ /* 2^255 - 2^5 */ square(t1, t0);
+ /* 2^255 - 21 */ mult(out, t1, z11);
+}
+
+/*
+ * Computes q = Curve25519(p, s)
+ */
+SECStatus
+ec_Curve25519_mul(PRUint8 *q, const PRUint8 *s, const PRUint8 *p)
+{
+ elem point = { 0 };
+ elem x_2 = { 0 };
+ elem z_2 = { 0 };
+ elem X = { 0 };
+ elem scalar = { 0 };
+ uint32_t i;
+
+ /* read and mask scalar */
+ for (i = 0; i < 32; ++i) {
+ scalar[i] = s[i];
+ }
+ scalar[0] &= 0xF8;
+ scalar[31] &= 0x7F;
+ scalar[31] |= 64;
+
+ /* read and mask point */
+ for (i = 0; i < 32; ++i) {
+ point[i] = p[i];
+ }
+ point[31] &= 0x7F;
+
+ monty(x_2, z_2, point, scalar);
+ recip(z_2, z_2);
+ mult(X, x_2, z_2);
+ reduce(X);
+ for (i = 0; i < 32; ++i) {
+ q[i] = X[i];
+ }
+ return 0;
+}
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