Data Encryption

Data encryption is the process of scrambling stored or transmitted information so that it is unintelligible
until it is unscrambled by the intended recipient. The intended recipient can then decode (or decrypt) the
information. PHP offers multiple means to make this happen. However, none of these solutions are very
effective without the applications running on secure servers and connections. The following are a list of
the more common encryption functions in PHP:

• md5() - MD5 is a third-party hash algorithm that PHP can use to create a digital fingerprint of a piece
of data. It is next to impossible to (efficiently) recover the original text when a piece of data has been
encrypted with the md5 hash algorithm. It is also vastly unlikely that any different text string will
create an identical hash - a 'hash collision'. These properties make hashes ideally suited for storing an
application's passwords because although an attacker may compromise a part of the system and reveal
the list of password hashes, they can't determine from the hashes alone what the real passwords are.
The md5() function returns a 128-bit hash (32 hexadecimal characters) that can then be stored with
the ultimate outcome of comparing it for security purposes.

<?php
$string = "IamAbigFanofIceCream";
$string_md5 = md5($string);
if (md5($string) = $string_md5) {
print "$string = md5($string_md5)";
}
?>

Will print:

IamAbigFanofIceCream = md5(673d924425c45b1f2221fdfcbe2160cf)

• sha1() - SHA-1 (Secure Hash Algorithm 1) is another hashing algorithm that can be used by
PHP for encryption purposes. The sha1() function returns a 160-bit hash (40 hexadecimal
characters).

<?php
$string = "IamAbigFanofIceCream";
$string_sha1 = sha1($string);
if (sha1($string) == $string_sha1) {
print "$string = sha1($string_sha1)";
}
?>

Will print:

IamAbigFanofIceCream = sha1(e2a0049b70506530f7b9bfc8e5967505a5b366ec)