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<?php
if (class_exists('ParagonIE_Sodium_Core_X25519', false)) {
return;
}
/**
* Class ParagonIE_Sodium_Core_X25519
*/
abstract class ParagonIE_Sodium_Core_X25519 extends ParagonIE_Sodium_Core_Curve25519
{
/**
* Alters the objects passed to this method in place.
*
* @internal You should not use this directly from another application
*
* @param ParagonIE_Sodium_Core_Curve25519_Fe $f
* @param ParagonIE_Sodium_Core_Curve25519_Fe $g
* @param int $b
* @return void
* @psalm-suppress MixedAssignment
*/
public static function fe_cswap(
ParagonIE_Sodium_Core_Curve25519_Fe $f,
ParagonIE_Sodium_Core_Curve25519_Fe $g,
$b = 0
) {
$b = -$b;
$x0 = ($f->e0 ^ $g->e0) & $b;
$x1 = ($f->e1 ^ $g->e1) & $b;
$x2 = ($f->e2 ^ $g->e2) & $b;
$x3 = ($f->e3 ^ $g->e3) & $b;
$x4 = ($f->e4 ^ $g->e4) & $b;
$x5 = ($f->e5 ^ $g->e5) & $b;
$x6 = ($f->e6 ^ $g->e6) & $b;
$x7 = ($f->e7 ^ $g->e7) & $b;
$x8 = ($f->e8 ^ $g->e8) & $b;
$x9 = ($f->e9 ^ $g->e9) & $b;
$f->e0 ^= $x0;
$f->e1 ^= $x1;
$f->e2 ^= $x2;
$f->e3 ^= $x3;
$f->e4 ^= $x4;
$f->e5 ^= $x5;
$f->e6 ^= $x6;
$f->e7 ^= $x7;
$f->e8 ^= $x8;
$f->e9 ^= $x9;
$g->e0 ^= $x0;
$g->e1 ^= $x1;
$g->e2 ^= $x2;
$g->e3 ^= $x3;
$g->e4 ^= $x4;
$g->e5 ^= $x5;
$g->e6 ^= $x6;
$g->e7 ^= $x7;
$g->e8 ^= $x8;
$g->e9 ^= $x9;
}
/**
* @internal You should not use this directly from another application
*
* @param ParagonIE_Sodium_Core_Curve25519_Fe $f
* @return ParagonIE_Sodium_Core_Curve25519_Fe
*/
public static function fe_mul121666(ParagonIE_Sodium_Core_Curve25519_Fe $f)
{
$h0 = self::mul($f->e0, 121666, 17);
$h1 = self::mul($f->e1, 121666, 17);
$h2 = self::mul($f->e2, 121666, 17);
$h3 = self::mul($f->e3, 121666, 17);
$h4 = self::mul($f->e4, 121666, 17);
$h5 = self::mul($f->e5, 121666, 17);
$h6 = self::mul($f->e6, 121666, 17);
$h7 = self::mul($f->e7, 121666, 17);
$h8 = self::mul($f->e8, 121666, 17);
$h9 = self::mul($f->e9, 121666, 17);
$carry9 = ($h9 + (1 << 24)) >> 25;
$h0 += self::mul($carry9, 19, 5);
$h9 -= $carry9 << 25;
$carry1 = ($h1 + (1 << 24)) >> 25;
$h2 += $carry1;
$h1 -= $carry1 << 25;
$carry3 = ($h3 + (1 << 24)) >> 25;
$h4 += $carry3;
$h3 -= $carry3 << 25;
$carry5 = ($h5 + (1 << 24)) >> 25;
$h6 += $carry5;
$h5 -= $carry5 << 25;
$carry7 = ($h7 + (1 << 24)) >> 25;
$h8 += $carry7;
$h7 -= $carry7 << 25;
$carry0 = ($h0 + (1 << 25)) >> 26;
$h1 += $carry0;
$h0 -= $carry0 << 26;
$carry2 = ($h2 + (1 << 25)) >> 26;
$h3 += $carry2;
$h2 -= $carry2 << 26;
$carry4 = ($h4 + (1 << 25)) >> 26;
$h5 += $carry4;
$h4 -= $carry4 << 26;
$carry6 = ($h6 + (1 << 25)) >> 26;
$h7 += $carry6;
$h6 -= $carry6 << 26;
$carry8 = ($h8 + (1 << 25)) >> 26;
$h9 += $carry8;
$h8 -= $carry8 << 26;
return new ParagonIE_Sodium_Core_Curve25519_Fe($h0, $h1, $h2, $h3, $h4, $h5, $h6, $h7, $h8, $h9);
}
/**
* @internal You should not use this directly from another application
*
* Inline comments preceded by # are from libsodium's ref10 code.
*
* @param string $n
* @param string $p
* @return string
* @throws SodiumException
* @throws TypeError
*/
public static function crypto_scalarmult_curve25519_ref10($n, $p)
{
# for (i = 0;i < 32;++i) e[i] = n[i];
$e = '' . $n;
# e[0] &= 248;
$e[0] = self::intToChr(
self::chrToInt($e[0]) & 248
);
# e[31] &= 127;
# e[31] |= 64;
$e[31] = self::intToChr(
(self::chrToInt($e[31]) & 127) | 64
);
# fe_frombytes(x1,p);
$x1 = self::fe_frombytes($p);
# fe_1(x2);
$x2 = self::fe_1();
# fe_0(z2);
$z2 = self::fe_0();
# fe_copy(x3,x1);
$x3 = self::fe_copy($x1);
# fe_1(z3);
$z3 = self::fe_1();
# swap = 0;
/** @var int $swap */
$swap = 0;
# for (pos = 254;pos >= 0;--pos) {
for ($pos = 254; $pos >= 0; --$pos) {
# b = e[pos / 8] >> (pos & 7);
/** @var int $b */
$b = self::chrToInt(
$e[(int) floor($pos / 8)]
) >> ($pos & 7);
# b &= 1;
$b &= 1;
# swap ^= b;
$swap ^= $b;
# fe_cswap(x2,x3,swap);
self::fe_cswap($x2, $x3, $swap);
# fe_cswap(z2,z3,swap);
self::fe_cswap($z2, $z3, $swap);
# swap = b;
$swap = $b;
# fe_sub(tmp0,x3,z3);
$tmp0 = self::fe_sub($x3, $z3);
# fe_sub(tmp1,x2,z2);
$tmp1 = self::fe_sub($x2, $z2);
# fe_add(x2,x2,z2);
$x2 = self::fe_add($x2, $z2);
# fe_add(z2,x3,z3);
$z2 = self::fe_add($x3, $z3);
# fe_mul(z3,tmp0,x2);
$z3 = self::fe_mul($tmp0, $x2);
# fe_mul(z2,z2,tmp1);
$z2 = self::fe_mul($z2, $tmp1);
# fe_sq(tmp0,tmp1);
$tmp0 = self::fe_sq($tmp1);
# fe_sq(tmp1,x2);
$tmp1 = self::fe_sq($x2);
# fe_add(x3,z3,z2);
$x3 = self::fe_add($z3, $z2);
# fe_sub(z2,z3,z2);
$z2 = self::fe_sub($z3, $z2);
# fe_mul(x2,tmp1,tmp0);
$x2 = self::fe_mul($tmp1, $tmp0);
# fe_sub(tmp1,tmp1,tmp0);
$tmp1 = self::fe_sub($tmp1, $tmp0);
# fe_sq(z2,z2);
$z2 = self::fe_sq($z2);
# fe_mul121666(z3,tmp1);
$z3 = self::fe_mul121666($tmp1);
# fe_sq(x3,x3);
$x3 = self::fe_sq($x3);
# fe_add(tmp0,tmp0,z3);
$tmp0 = self::fe_add($tmp0, $z3);
# fe_mul(z3,x1,z2);
$z3 = self::fe_mul($x1, $z2);
# fe_mul(z2,tmp1,tmp0);
$z2 = self::fe_mul($tmp1, $tmp0);
}
# fe_cswap(x2,x3,swap);
self::fe_cswap($x2, $x3, $swap);
# fe_cswap(z2,z3,swap);
self::fe_cswap($z2, $z3, $swap);
# fe_invert(z2,z2);
$z2 = self::fe_invert($z2);
# fe_mul(x2,x2,z2);
$x2 = self::fe_mul($x2, $z2);
# fe_tobytes(q,x2);
return self::fe_tobytes($x2);
}
/**
* @internal You should not use this directly from another application
*
* @param ParagonIE_Sodium_Core_Curve25519_Fe $edwardsY
* @param ParagonIE_Sodium_Core_Curve25519_Fe $edwardsZ
* @return ParagonIE_Sodium_Core_Curve25519_Fe
*/
public static function edwards_to_montgomery(
ParagonIE_Sodium_Core_Curve25519_Fe $edwardsY,
ParagonIE_Sodium_Core_Curve25519_Fe $edwardsZ
) {
$tempX = self::fe_add($edwardsZ, $edwardsY);
$tempZ = self::fe_sub($edwardsZ, $edwardsY);
$tempZ = self::fe_invert($tempZ);
return self::fe_mul($tempX, $tempZ);
}
/**
* @internal You should not use this directly from another application
*
* @param string $n
* @return string
* @throws SodiumException
* @throws TypeError
*/
public static function crypto_scalarmult_curve25519_ref10_base($n)
{
# for (i = 0;i < 32;++i) e[i] = n[i];
$e = '' . $n;
# e[0] &= 248;
$e[0] = self::intToChr(
self::chrToInt($e[0]) & 248
);
# e[31] &= 127;
# e[31] |= 64;
$e[31] = self::intToChr(
(self::chrToInt($e[31]) & 127) | 64
);
$A = self::ge_scalarmult_base($e);
if (
!($A->Y instanceof ParagonIE_Sodium_Core_Curve25519_Fe)
||
!($A->Z instanceof ParagonIE_Sodium_Core_Curve25519_Fe)
) {
throw new TypeError('Null points encountered');
}
$pk = self::edwards_to_montgomery($A->Y, $A->Z);
return self::fe_tobytes($pk);
}
}
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