ParagonIE_Sodium_Compat::crypto_kdf_derive_from_key( int $subkey_len, int $subkey_id, string $context, string $key ): string

Compatibility

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

Parameters

$subkey_lenint

$subkey_idint

$contextstring

$keystring

Return value

string

Performance profile

How much work a call to ParagonIE_Sodium_Compat::crypto_kdf_derive_from_key() 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

39–68

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 88.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

1

1 place in core call this, so the cost is paid more often than your own code shows.

What one call costs · 4 distinct outcomes

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

Uses · 6

• ParagonIE_Sodium_Core_Util::declareScalarType()If a variable does not match a given type, throw a TypeError.
• SodiumException::__construct()
• ParagonIE_Sodium_Core_Util::strlen()Safe string length
• ParagonIE_Sodium_Core_Util::store64_le()Stores a 64-bit integer as an string, treating it as little-endian.
• ParagonIE_Sodium_Compat::crypto_generichash_init_salt_personal()Initialize a BLAKE2b hashing context, for use in a streaming interface.
• ParagonIE_Sodium_Compat::crypto_generichash_final()Get the final BLAKE2b hash output for a given context.

Used by · 1

• sodium_crypto_kdf_derive_from_key()

Source code

View on Trac ↗View on GitHub ↗

1944    public static function crypto_kdf_derive_from_key(1945        $subkey_len,1946        $subkey_id,1947        $context,1948        #[\SensitiveParameter]1949        $key1950    ) {1951        ParagonIE_Sodium_Core_Util::declareScalarType($subkey_len, 'int', 1);1952        ParagonIE_Sodium_Core_Util::declareScalarType($subkey_id, 'int', 2);1953        ParagonIE_Sodium_Core_Util::declareScalarType($context, 'string', 3);1954        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);1955        $subkey_id = (int) $subkey_id;1956        $subkey_len = (int) $subkey_len;1957        $context = (string) $context;1958        $key = (string) $key;1959 1960        if ($subkey_len < self::CRYPTO_KDF_BYTES_MIN) {1961            throw new SodiumException('subkey cannot be smaller than SODIUM_CRYPTO_KDF_BYTES_MIN');1962        }1963        if ($subkey_len > self::CRYPTO_KDF_BYTES_MAX) {1964            throw new SodiumException('subkey cannot be larger than SODIUM_CRYPTO_KDF_BYTES_MAX');1965        }1966        if ($subkey_id < 0) {1967            throw new SodiumException('subkey_id cannot be negative');1968        }1969        if (ParagonIE_Sodium_Core_Util::strlen($context) !== self::CRYPTO_KDF_CONTEXTBYTES) {1970            throw new SodiumException('context should be SODIUM_CRYPTO_KDF_CONTEXTBYTES bytes');1971        }1972        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_KDF_KEYBYTES) {1973            throw new SodiumException('key should be SODIUM_CRYPTO_KDF_KEYBYTES bytes');1974        }1975 1976        $salt = ParagonIE_Sodium_Core_Util::store64_le($subkey_id);1977        $state = self::crypto_generichash_init_salt_personal(1978            $key,1979            $subkey_len,1980            $salt,1981            $context1982        );1983        return self::crypto_generichash_final($state, $subkey_len);1984    }

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

Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/sodium_compat/src/Compat.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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