ParagonIE_Sodium_Core_Curve25519::ge_scalarmult_base( string $a ): ParagonIE_Sodium_Core_Curve25519_Ge_P3

2017    public static function ge_scalarmult_base($a)2018    {2019        /** @var array<int, int> $e */2020        $e = array();2021        $r = new ParagonIE_Sodium_Core_Curve25519_Ge_P1p1();2022 2023        for ($i = 0; $i < 32; ++$i) {2024            $dbl = (int) $i << 1;2025            $e[$dbl] = (int) self::chrToInt($a[$i]) & 15;2026            $e[$dbl + 1] = (int) (self::chrToInt($a[$i]) >> 4) & 15;2027        }2028 2029        $carry = 0;2030        for ($i = 0; $i < 63; ++$i) {2031            $e[$i] += $carry;2032            $carry = $e[$i] + 8;2033            $carry >>= 4;2034            $e[$i] -= $carry << 4;2035        }2036        $e[63] += (int) $carry;2037 2038        $h = self::ge_p3_0();2039 2040        for ($i = 1; $i < 64; $i += 2) {2041            $t = self::ge_select((int) floor($i / 2), (int) $e[$i]);2042            $r = self::ge_madd($r, $h, $t);2043            $h = self::ge_p1p1_to_p3($r);2044        }2045 2046        $r = self::ge_p3_dbl($h);2047 2048        $s = self::ge_p1p1_to_p2($r);2049        $r = self::ge_p2_dbl($s);2050        $s = self::ge_p1p1_to_p2($r);2051        $r = self::ge_p2_dbl($s);2052        $s = self::ge_p1p1_to_p2($r);2053        $r = self::ge_p2_dbl($s);2054 2055        $h = self::ge_p1p1_to_p3($r);2056 2057        for ($i = 0; $i < 64; $i += 2) {2058            $t = self::ge_select($i >> 1, (int) $e[$i]);2059            $r = self::ge_madd($r, $h, $t);2060            $h = self::ge_p1p1_to_p3($r);2061        }2062        return $h;2063    }