Generate a HKDF key derivation of a supplied key input
Syntax
hash_hkdf(
string $algo,
string $key,
int $length = 0,
string $info = "",
string $salt = ""
): stringParameters
algoName of selected hashing algorithm.
keyInput keying material (raw binary). Cannot be empty.
lengthDesired output length in bytes. Cannot be greater than 255 times the chosen hash function size.
If length is 0, the output length will default to the chosen hash function size.
infoApplication/context-specific info string.
saltSalt to use during derivation.
While optional, adding random salt significantly improves the strength of HKDF.
Return
Returns a string containing a raw binary representation of the derived key (also known as output keying material - OKM).
Examples
1 · algo key
<? $algo = 'sha384'; $key = random_bytes(32); $return = hash_hkdf($algo, $key); echo $return . PHP_EOL . bin2hex($return); ?>
� � Df�0��DR �C �U�S� ���4��t ��Bg�lO�� f2ba1ff0204466e430bcdc445200a1431dd155f5530816e0b71ceee80fac1634b4af741e0f1418fbb14267ee6c4ffffa
2 · length
<? $algo = 'sha384'; $key = random_bytes(32); $length = 32; $return = hash_hkdf($algo, $key, $length); echo $return . PHP_EOL . bin2hex($return); ?>
� �n���q�Ѭ���\�>\D��b3 d61c7fe66e8ec1d0120771a6d1ac14bee0e6a40f035ceb3e5c44fbf49bb86233
3 · info
<? $algo = 'sha384'; $key = random_bytes(32); $length = 32; $info = 'sha-384-authentication'; $return = hash_hkdf($algo, $key, $length, $info); echo $return . PHP_EOL . bin2hex($return); ?>
����B^��W�۹�˓���S ^*���4��� aaf07fb5f8425ebfca57d2dbb9e7cb93a6b0b3531c5e112aa489df34cf0eb88a
4 · salt
<? $algo = 'sha384'; $key = random_bytes(32); $length = 32; $info = 'sha-384-authentication'; $salt = random_bytes(16); $return = hash_hkdf($algo, $key, $length, $info, $salt); echo $return . PHP_EOL . bin2hex($return); ?>
=��>���l� �8t2��'�+v��Q�m�d}?E 3d85a73e9ee6f26cfd1ea4387432cbf3279d2b087681b351876d15f9647d3f45
