Encrypted Storage Model
SSL/SSH protects data travelling from the client to the server: SSL/SSH does not protect persistent data stored in a database. SSL is an on-the-wire protocol.
Once an attacker gains access to your database directly (bypassing the webserver), stored sensitive data may be exposed or misused, unless the information is protected by the database itself. Encrypting the data is a good way to mitigate this threat, but very few databases offer this type of data encryption.
The easiest way to work around this problem is to first create your own encryption package, and then use it from within your PHP scripts. PHP can assist you in this with several extensions, such as Mcrypt and Mhash, covering a wide variety of encryption algorithms. The script encrypts the data before inserting it into the database, and decrypts it when retrieving. See the references for further examples of how encryption works.
Hashing
In the case of truly hidden data, if its raw representation is not needed (i.e. will not be displayed), hashing should be taken into consideration. The well-known example for hashing is storing the cryptographic hash of a password in a database, instead of the password itself.
In PHP 5.5 or newer password functions provide a convenient way to hash sensitive data and work with these hashes. In PHP 5.3.7+ » password_compat library can also be used.
password_hash() is used to hash a given string using the strongest algorithm currently available and password_verify() checks whether the given password matches the hash stored in database.
Example #1 Hashing password field
<?php
// storing password hash
$query = sprintf("INSERT INTO users(name,pwd) VALUES('%s','%s');",
pg_escape_string($username),
password_hash($password, PASSWORD_DEFAULT));
$result = pg_query($connection, $query);
// querying if user submitted the right password
$query = sprintf("SELECT pwd FROM users WHERE name='%s';",
pg_escape_string($username));
$row = pg_fetch_assoc(pg_query($connection, $query));
if ($row && password_verify($password, $row['pwd'])) {
echo 'Welcome, ' . htmlspecialchars($username) . '!';
} else {
echo 'Authentication failed for ' . htmlspecialchars($username) . '.';
}
?>
In older versions of PHP this can be achieved using crypt() function.
Example #2 Hashing password using crypt()s
<?php
// storing password hash
// $random_chars retrieved e.g. using /dev/random
$query = sprintf("INSERT INTO users(name,pwd) VALUES('%s','%s');",
pg_escape_string($username),
pg_escape_string(crypt($password, '$2a$07$' . $random_chars . '$')));
$result = pg_query($connection, $query);
// querying if user submitted the right password
$query = sprintf("SELECT pwd FROM users WHERE name='%s';",
pg_escape_string($username));
$row = pg_fetch_assoc(pg_query($connection, $query));
if ($row && crypt($password, $row['pwd']) == $row['pwd']) {
echo 'Welcome, ' . htmlspecialchars($username) . '!';
} else {
echo 'Authentication failed for ' . htmlspecialchars($username) . '.';
}
?>
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Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-security.database.storage.html
The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.
References
These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.
