ParagonIE_Sodium_Core32_Curve25519::ge_frombytes_negate_vartime( string $s ): ParagonIE_Sodium_Core32_Curve25519_Ge_P3

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$sstring

Return value

ParagonIE_Sodium_Core32_Curve25519_Ge_P3

Performance profile

How much work a call to ParagonIE_Sodium_Core32_Curve25519::ge_frombytes_negate_vartime() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Trivial

Touches nothing outside its own arguments.

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

127–242

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 246.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

0

Nothing in core calls this; the cost is only what you spend yourself.

What one call costs · 10 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost ParagonIE_Sodium_Core32_Curve25519::ge_frombytes_negate_vartime() can have, taken from its control-flow graph on PHP 8.5.

Uses · 17

• ParagonIE_Sodium_Core32_Curve25519_Fe::fromArray()
• ParagonIE_Sodium_Core32_Int32::fromInt()
• ParagonIE_Sodium_Core32_Curve25519_Ge_P3::__construct()ParagonIE_Sodium_Core32_Curve25519_Ge_P3 constructor.
• ParagonIE_Sodium_Core32_Curve25519::fe_0()Get a field element of size 10 with a value of 0
• ParagonIE_Sodium_Core32_Curve25519::fe_frombytes()Give: 32-byte string.
• ParagonIE_Sodium_Core32_Curve25519::fe_1()Get a field element of size 10 with a value of 1
• ParagonIE_Sodium_Core32_Curve25519::fe_sq()Square a field element
• ParagonIE_Sodium_Core32_Curve25519::fe_mul()Multiply two field elements
• ParagonIE_Sodium_Core32_Curve25519::fe_sub()Subtract two field elements.
• ParagonIE_Sodium_Core32_Curve25519::fe_add()Add two field elements.
• ParagonIE_Sodium_Core32_Curve25519::fe_pow22523()
• ParagonIE_Sodium_Core32_Curve25519::fe_isnonzero()Returns 0 if this field element results in all NUL bytes.

Source code

View on Trac ↗View on GitHub ↗

1441    public static function ge_frombytes_negate_vartime($s)1442    {1443        static $d = null;1444        if (!$d) {1445            $d = ParagonIE_Sodium_Core32_Curve25519_Fe::fromArray(1446                array(1447                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[0]),1448                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[1]),1449                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[2]),1450                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[3]),1451                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[4]),1452                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[5]),1453                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[6]),1454                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[7]),1455                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[8]),1456                    ParagonIE_Sodium_Core32_Int32::fromInt(self::$d[9])1457                )1458            );1459        }1460        /** @var ParagonIE_Sodium_Core32_Curve25519_Fe $d */1461 1462        # fe_frombytes(h->Y,s);1463        # fe_1(h->Z);1464        $h = new ParagonIE_Sodium_Core32_Curve25519_Ge_P3(1465            self::fe_0(),1466            self::fe_frombytes($s),1467            self::fe_1()1468        );1469 1470        # fe_sq(u,h->Y);1471        # fe_mul(v,u,d);1472        # fe_sub(u,u,h->Z);       /* u = y^2-1 */1473        # fe_add(v,v,h->Z);       /* v = dy^2+1 */1474        $u = self::fe_sq($h->Y);1475        /** @var ParagonIE_Sodium_Core32_Curve25519_Fe $d */1476        $v = self::fe_mul($u, $d);1477        $u = self::fe_sub($u, $h->Z); /* u =  y^2 - 1 */1478        $v = self::fe_add($v, $h->Z); /* v = dy^2 + 1 */1479 1480        # fe_sq(v3,v);1481        # fe_mul(v3,v3,v);        /* v3 = v^3 */1482        # fe_sq(h->X,v3);1483        # fe_mul(h->X,h->X,v);1484        # fe_mul(h->X,h->X,u);    /* x = uv^7 */1485        $v3 = self::fe_sq($v);1486        $v3 = self::fe_mul($v3, $v); /* v3 = v^3 */1487        $h->X = self::fe_sq($v3);1488        $h->X = self::fe_mul($h->X, $v);1489        $h->X = self::fe_mul($h->X, $u); /* x = uv^7 */1490 1491        # fe_pow22523(h->X,h->X); /* x = (uv^7)^((q-5)/8) */1492        # fe_mul(h->X,h->X,v3);1493        # fe_mul(h->X,h->X,u);    /* x = uv^3(uv^7)^((q-5)/8) */1494        $h->X = self::fe_pow22523($h->X); /* x = (uv^7)^((q-5)/8) */1495        $h->X = self::fe_mul($h->X, $v3);1496        $h->X = self::fe_mul($h->X, $u); /* x = uv^3(uv^7)^((q-5)/8) */1497 1498        # fe_sq(vxx,h->X);1499        # fe_mul(vxx,vxx,v);1500        # fe_sub(check,vxx,u);    /* vx^2-u */1501        $vxx = self::fe_sq($h->X);1502        $vxx = self::fe_mul($vxx, $v);1503        $check = self::fe_sub($vxx, $u); /* vx^2 - u */1504 1505        # if (fe_isnonzero(check)) {1506        #     fe_add(check,vxx,u);  /* vx^2+u */1507        #     if (fe_isnonzero(check)) {1508        #         return -1;1509        #     }1510        #     fe_mul(h->X,h->X,sqrtm1);1511        # }1512        if (self::fe_isnonzero($check)) {1513            $check = self::fe_add($vxx, $u); /* vx^2 + u */1514            if (self::fe_isnonzero($check)) {1515                throw new RangeException('Internal check failed.');1516            }1517            $h->X = self::fe_mul(1518                $h->X,1519                ParagonIE_Sodium_Core32_Curve25519_Fe::fromIntArray(self::$sqrtm1)1520            );

Changelog

Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

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