Simple one-way encryption in PHP

OneWayEncryption.php

<?php

class OneWayEncryption{
    /*
    * One way encryption; hash + salt
    */

    private const COST = '14';

    private function uniqueSalt() {
        return substr( strtr( base64_encode( random_bytes( 16 ) ), '+', '.' ), 0, 22 );
    }

    public function createHash( $string ) {
        return crypt( $string, ( '$2a$' . self::COST . '$' . $this->uniqueSalt() ) );
    }

    public function checkPassword( $hash, $password ) {
        // First 29 characters incl. algo + cost + salt
        $full_salt = substr( $hash, 0, 29 );
        
        // Hash
        $new_hash = crypt( $password, $full_salt );
        
        // Return
        if( hash_equals( $hash, $new_hash ) ) return TRUE;
    }
}

# Encryption
$encryptor = new OneWayEncryption();

# Create hash (and save to DB)
$salty_hash = $encryptor->createHash('mypassword123');

# Check hash
if($encryptor->checkPassword($db_password_entry, 'mypassword123')){
    # Correct password: proceed with login, session creation, etc.
}

?>