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sodium_crypto_pwhash

(PHP 7 >= 7.2.0)

sodium_crypto_pwhashDerive a key from a password

説明

sodium_crypto_pwhash ( int $length , string $password , string $salt , int $opslimit , int $memlimit [, int $alg ] ) : string

This function provides low-level access to libsodium's crypto_pwhash key derivation function. Unless you have specific reason to use this function, you should use sodium_crypto_pwhash_str() or password_hash() functions instead.

パラメータ

length

integer; The length of the password hash to generate, in bytes.

password

string; The password to generate a hash for.

salt

string A salt to add to the password before hashing. The salt should be unpredictable, ideally generated from a good random mumber source such as random_bytes(), and have a length of at least SODIUM_CRYPTO_PWHASH_SALTBYTES bytes.

opslimit

Represents a maximum amount of computations to perform. Raising this number will make the function require more CPU cycles to compute a key. There are some constants available to set the operations limit to appropriate values depending on intended use, in order of strength: SODIUM_CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE, SODIUM_CRYPTO_PWHASH_OPSLIMIT_MODERATE and SODIUM_CRYPTO_PWHASH_OPSLIMIT_SENSITIVE.

memlimit

The maximum amount of RAM that the function will use, in bytes. There are constants to help you choose an appropriate value, in order of size: SODIUM_CRYPTO_PWHASH_MEMLIMIT_INTERACTIVE, SODIUM_CRYPTO_PWHASH_MEMLIMIT_MODERATE, and SODIUM_CRYPTO_PWHASH_MEMLIMIT_SENSITIVE. Typically these should be paired with the matching opslimit values.

alg

integer A number indicating the hash algorithm to use. By default SODIUM_CRYPTO_PWHASH_ALG_DEFAULT (the currently recommended algorithm, which can change from one version of libsodium to another), or explicitly using SODIUM_CRYPTO_PWHASH_ALG_ARGON2ID13, representing the Argon2id algorithm version 1.3.

返り値

Returns the derived key, 失敗した場合に FALSE を返します. The return value is a binary string of the hash, not an ASCII-encoded representation, and does not contain additional information about the parameters used to create the hash, so you will need to keep that information if you are ever going to verify the password in future. Use sodium_crypto_pwhash_str() to avoid needing to do all that.

例1 password_hash() example

<?php
//Need to keep the salt if we're ever going to be able to check this password
$salt random_bytes(SODIUM_CRYPTO_PWHASH_SALTBYTES);
//Using bin2hex to keep output readable
echo bin2hex(
    
sodium_crypto_pwhash(
        
16// == 128 bits
        
'password',
        
$salt,
        
SODIUM_CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE,
        
SODIUM_CRYPTO_PWHASH_MEMLIMIT_INTERACTIVE,
        
SODIUM_CRYPTO_PWHASH_ALG_ARGON2ID13
    
)
);
?>

上の例の出力は、 たとえば以下のようになります。

a18f346ba57992eb7e4ae6abf3fd30ee

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