Oihana PHP

kdfIsAvailable.php

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Functions

kdfIsAvailable()  : bool
Tells whether the KDF a file names can actually be run here.

Functions

kdfIsAvailable()

Tells whether the KDF a file names can actually be run here.

kdfIsAvailable(int $algorithm[, bool|null $sodiumLoaded = null ]) : bool

Every encrypted file stores the identifier of the KDF its key was derived with, so a reader never has to guess. What that byte cannot do is make the KDF available: EncryptionFormat::KDF_ARGON2ID needs ext-sodium at decryption time exactly as much as at encryption time, and ext-sodium is a suggestion of this package, not a requirement.

Which produces the one case worth a function of its own: a file written on a host that has sodium, read on a host that does not. Measured on 2026-10-24, that read failed with "Decryption failed due to incorrect passphrase or corrupted data" — on an intact archive, with the right passphrase, because the real cause sat in a wrapped exception nobody prints. For someone restoring a backup, that message sends them looking for a lost passphrase or a corrupt file instead of a missing extension.

EncryptionFormat::KDF_PBKDF2_SHA256 is native to PHP, so it is available everywhere.

An unknown identifier answers true, and that is deliberate: it names no implementation that could be missing. A byte that is neither of the two known values is a corrupt or tampered header, or one from a newer release — all of which deriveKey() must reject, and under the generic message, since a forged byte must not get an answer of its own.

Parameters
$algorithm : int
$sodiumLoaded : bool|null = null

Whether ext-sodium is loaded. Testing seam; null asks function_exists().

Tags
example 
use function oihana\files\openssl\kdfIsAvailable;
use oihana\files\openssl\enums\EncryptionFormat;

kdfIsAvailable( EncryptionFormat::KDF_ARGON2ID ) ;             // false without ext-sodium
kdfIsAvailable( EncryptionFormat::KDF_PBKDF2_SHA256 ) ;        // always true
kdfIsAvailable( EncryptionFormat::KDF_ARGON2ID , false ) ;     // false
author

Marc Alcaraz (ekameleon)

since
1.5.0
Return values
bool
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