hash_hkdf

Function • Misc changes in PHP 8.2

Generate a HKDF key derivation of a supplied key input.

PHP 5
PHP 7.0
PHP 7.1
Added
PHP 7.2-7.4
PHP 8.0
Improved
PHP 8.1
PHP 8.2
Changed
PHP 8.3
PHP 8.4
PHP 8.5
PHP 8.6

hash_hkdf Function synopsis

hash_hkdf(
    string $algo,
    string $key,
    int $length = 0,
    string $info = "",
    string $salt = ""
  ): string

Parameters

$algo

Typestring

Name of selected hashing algorithm (e.g. "sha256"). For a list of supported algorithms see hash_hmac_algos.

$key

Typestring

Input keying material (raw binary). Cannot be empty.

$length

OptionalTypeintDefault value0

Desired output length in bytes. Cannot be greater than 255 times the chosen hash function size.

$info

OptionalTypestringDefault value""

Application/context-specific info string.

$salt

OptionalTypestringDefault value""

Salt to use during derivation.

Return value

Typestring

Returns a string containing a raw binary representation of the derived key (also known as output keying material - OKM).

Changes to the hash_hkdf Function

PHP 8.2

PHP 8.0

  • Return type added: string
  • Parameter name of parameter #1 changed: $ikm to $algo
  • Parameter type added for parameter #1 ($algo): string
  • Parameter name of parameter #2 changed: $algo to $key
  • Parameter type added for parameter #2 ($key): string
  • Parameter type added for parameter #3 ($length): int
  • Parameter default value added for position #3 ($length): 0
  • Parameter name of parameter #4 changed: $string to $info
  • Parameter type added for parameter #4 ($info): string
  • Parameter default value added for position #4 ($info): ""
  • Parameter type added for parameter #5 ($salt): string
  • Parameter default value added for position #5 ($salt): ""
  hash_hkdf(
-     $ikm,
+     string $algo,
-     $algo,
+     string $key,
-     $length,
+     int $length = 0,
-     $string,
+     string $info = "",
-     $salt
+     string $salt = ""
-   )
+   ): string

PHP 7.1

  • Function added

hash_hkdf Function Availability

PHP VersionAvailability
PHP 8.6Upcoming Release Yes
PHP 8.5Supported (Latest) Yes
PHP 8.4Supported Yes
PHP 8.3Security-Fixes Only Yes
PHP 8.2Security-Fixes Only Yes
PHP 8.1Unsupported Yes
PHP 8.0Unsupported Yes
PHP 7.4Unsupported Yes
PHP 7.3Unsupported Yes
PHP 7.2Unsupported Yes
PHP 7.1Unsupported Yes
PHP 7.0Unsupported No
PHP 5.6Unsupported No
PHP 5.5Unsupported No
PHP 5.4Unsupported No
PHP 5.3Unsupported No