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-rw-r--r--app/src/main/java/com/wireguard/crypto/Curve25519.java111
1 files changed, 56 insertions, 55 deletions
diff --git a/app/src/main/java/com/wireguard/crypto/Curve25519.java b/app/src/main/java/com/wireguard/crypto/Curve25519.java
index 694f557b..a20c9f97 100644
--- a/app/src/main/java/com/wireguard/crypto/Curve25519.java
+++ b/app/src/main/java/com/wireguard/crypto/Curve25519.java
@@ -21,28 +21,28 @@ import java.util.Arrays;
* <p>
* References: http://cr.yp.to/ecdh.html, RFC 7748
*/
-@SuppressWarnings("ALL")
+@SuppressWarnings("MagicNumber")
public final class Curve25519 {
// Numbers modulo 2^255 - 19 are broken up into ten 26-bit words.
private static final int NUM_LIMBS_255BIT = 10;
private static final int NUM_LIMBS_510BIT = 20;
- private int[] A;
- private int[] AA;
- private int[] B;
- private int[] BB;
- private int[] C;
- private int[] CB;
- private int[] D;
- private int[] DA;
- private int[] E;
- private long[] t1;
- private int[] t2;
- private int[] x_1;
- private int[] x_2;
- private int[] x_3;
- private int[] z_2;
- private int[] z_3;
+ private final int[] A;
+ private final int[] AA;
+ private final int[] B;
+ private final int[] BB;
+ private final int[] C;
+ private final int[] CB;
+ private final int[] D;
+ private final int[] DA;
+ private final int[] E;
+ private final long[] t1;
+ private final int[] t2;
+ private final int[] x_1;
+ private final int[] x_2;
+ private final int[] x_3;
+ private final int[] z_2;
+ private final int[] z_3;
/**
* Constructs the temporary state holder for Curve25519 evaluation.
@@ -74,11 +74,10 @@ public final class Curve25519 {
* @param x The first value.
* @param y The second value.
*/
- private static void cswap(int select, int[] x, int[] y) {
- int dummy;
+ private static void cswap(int select, final int[] x, final int[] y) {
select = -select;
for (int index = 0; index < NUM_LIMBS_255BIT; ++index) {
- dummy = select & (x[index] ^ y[index]);
+ final int dummy = select & (x[index] ^ y[index]);
x[index] ^= dummy;
y[index] ^= dummy;
}
@@ -93,17 +92,18 @@ public final class Curve25519 {
* @param publicKey The public key to use in the evaluation, or null
* if the base point of the curve should be used.
*/
- public static void eval(byte[] result, int offset, byte[] privateKey, byte[] publicKey) {
- Curve25519 state = new Curve25519();
+ public static void eval(final byte[] result, final int offset,
+ final byte[] privateKey, final byte[] publicKey) {
+ final Curve25519 state = new Curve25519();
try {
// Unpack the public key value. If null, use 9 as the base point.
Arrays.fill(state.x_1, 0);
if (publicKey != null) {
// Convert the input value from little-endian into 26-bit limbs.
for (int index = 0; index < 32; ++index) {
- int bit = (index * 8) % 26;
- int word = (index * 8) / 26;
- int value = publicKey[index] & 0xFF;
+ final int bit = (index * 8) % 26;
+ final int word = (index * 8) / 26;
+ final int value = publicKey[index] & 0xFF;
if (bit <= (26 - 8)) {
state.x_1[word] |= value << bit;
} else {
@@ -139,8 +139,8 @@ public final class Curve25519 {
// Convert x_2 into little-endian in the result buffer.
for (int index = 0; index < 32; ++index) {
- int bit = (index * 8) % 26;
- int word = (index * 8) / 26;
+ final int bit = (index * 8) % 26;
+ final int word = (index * 8) / 26;
if (bit <= (26 - 8))
result[offset + index] = (byte) (state.x_2[word] >> bit);
else
@@ -159,11 +159,11 @@ public final class Curve25519 {
* @param x The first number to add.
* @param y The second number to add.
*/
- private void add(int[] result, int[] x, int[] y) {
- int index, carry;
+ private void add(final int[] result, final int[] x, final int[] y) {
+ int carry;
carry = x[0] + y[0];
result[0] = carry & 0x03FFFFFF;
- for (index = 1; index < NUM_LIMBS_255BIT; ++index) {
+ for (int index = 1; index < NUM_LIMBS_255BIT; ++index) {
carry = (carry >> 26) + x[index] + y[index];
result[index] = carry & 0x03FFFFFF;
}
@@ -198,19 +198,17 @@ public final class Curve25519 {
*
* @param s The 32-byte secret key.
*/
- private void evalCurve(byte[] s) {
+ private void evalCurve(final byte[] s) {
int sposn = 31;
- int sbit = 6;
int svalue = s[sposn] | 0x40;
int swap = 0;
- int select;
// Iterate over all 255 bits of "s" from the highest to the lowest.
// We ignore the high bit of the 256-bit representation of "s".
- for (; ; ) {
+ for (int sbit = 6; ; ) {
// Conditional swaps on entry to this bit but only if we
// didn't swap on the previous bit.
- select = (svalue >> sbit) & 0x01;
+ final int select = (svalue >> sbit) & 0x01;
swap ^= select;
cswap(swap, x_2, x_3);
cswap(swap, z_2, z_3);
@@ -264,8 +262,8 @@ public final class Curve25519 {
* @param x The first number to multiply.
* @param y The second number to multiply.
*/
- private void mul(int[] result, int[] x, int[] y) {
- int i, j;
+ private void mul(final int[] result, final int[] x, final int[] y) {
+ int i;
// Multiply the two numbers to create the intermediate result.
long v = x[0];
@@ -274,7 +272,7 @@ public final class Curve25519 {
}
for (i = 1; i < NUM_LIMBS_255BIT; ++i) {
v = x[i];
- for (j = 0; j < (NUM_LIMBS_255BIT - 1); ++j) {
+ for (int j = 0; j < (NUM_LIMBS_255BIT - 1); ++j) {
t1[i + j] += v * y[j];
}
t1[i + NUM_LIMBS_255BIT - 1] = v * y[NUM_LIMBS_255BIT - 1];
@@ -298,11 +296,10 @@ public final class Curve25519 {
* @param result The result.
* @param x The number to multiply by a24.
*/
- private void mulA24(int[] result, int[] x) {
- long a24 = 121665;
+ private void mulA24(final int[] result, final int[] x) {
+ final long a24 = 121665;
long carry = 0;
- int index;
- for (index = 0; index < NUM_LIMBS_255BIT; ++index) {
+ for (int index = 0; index < NUM_LIMBS_255BIT; ++index) {
carry += a24 * x[index];
t2[index] = ((int) carry) & 0x03FFFFFF;
carry >>= 26;
@@ -317,8 +314,8 @@ public final class Curve25519 {
* @param result The result. Must not overlap with x.
* @param x The argument.
*/
- private void pow250(int[] result, int[] x) {
- int i, j;
+ private void pow250(final int[] result, final int[] x) {
+ int j;
// The big-endian hexadecimal expansion of (2^250 - 1) is:
// 03FFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF
@@ -335,7 +332,7 @@ public final class Curve25519 {
for (j = 0; j < 9; ++j)
square(A, A);
mul(result, A, x);
- for (i = 0; i < 23; ++i) {
+ for (int i = 0; i < 23; ++i) {
for (j = 0; j < 10; ++j)
square(A, A);
mul(result, result, A);
@@ -357,7 +354,7 @@ public final class Curve25519 {
* @param result The result. Must not overlap with x.
* @param x The argument.
*/
- private void recip(int[] result, int[] x) {
+ private void recip(final int[] result, final int[] x) {
// The reciprocal is the same as x ^ (p - 2) where p = 2^255 - 19.
// The big-endian hexadecimal expansion of (p - 2) is:
// 7FFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFEB
@@ -383,8 +380,10 @@ public final class Curve25519 {
* modified during the reduction.
* @param size The number of limbs in the high order half of x.
*/
- private void reduce(int[] result, int[] x, int size) {
- int index, limb, carry;
+ private void reduce(final int[] result, final int[] x, final int size) {
+ int index;
+ int limb;
+ int carry;
// Calculate (x mod 2^255) + ((x / 2^255) * 19) which will
// either produce the answer we want or it will produce a
@@ -436,8 +435,9 @@ public final class Curve25519 {
*
* @param x The number to reduce, and the result.
*/
- private void reduceQuick(int[] x) {
- int index, carry;
+ private void reduceQuick(final int[] x) {
+ int index;
+ int carry;
// Perform a trial subtraction of (2^255 - 19) from "x" which is
// equivalent to adding 19 and subtracting 2^255. We add 19 here;
@@ -454,8 +454,8 @@ public final class Curve25519 {
// correct answer but do it in a way that instruction timing will not
// reveal which value was selected. Borrow will occur if bit 21 of
// "t2" is zero. Turn the bit into a selection mask.
- int mask = -((t2[NUM_LIMBS_255BIT - 1] >> 21) & 0x01);
- int nmask = ~mask;
+ final int mask = -((t2[NUM_LIMBS_255BIT - 1] >> 21) & 0x01);
+ final int nmask = ~mask;
t2[NUM_LIMBS_255BIT - 1] &= 0x001FFFFF;
for (index = 0; index < NUM_LIMBS_255BIT; ++index)
x[index] = (x[index] & nmask) | (t2[index] & mask);
@@ -467,7 +467,7 @@ public final class Curve25519 {
* @param result The result.
* @param x The number to square.
*/
- private void square(int[] result, int[] x) {
+ private void square(final int[] result, final int[] x) {
mul(result, x, x);
}
@@ -478,8 +478,9 @@ public final class Curve25519 {
* @param x The first number to subtract.
* @param y The second number to subtract.
*/
- private void sub(int[] result, int[] x, int[] y) {
- int index, borrow;
+ private static void sub(final int[] result, final int[] x, final int[] y) {
+ int index;
+ int borrow;
// Subtract y from x to generate the intermediate result.
borrow = 0;
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-15 22:46:43 +0000