Php md5 with key

PHP md5() Function

The md5() function calculates the MD5 hash of a string.

The md5() function uses the RSA Data Security, Inc. MD5 Message-Digest Algorithm.

From RFC 1321 — The MD5 Message-Digest Algorithm: «The MD5 message-digest algorithm takes as input a message of arbitrary length and produces as output a 128-bit «fingerprint» or «message digest» of the input. The MD5 algorithm is intended for digital signature applications, where a large file must be «compressed» in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA.»

To calculate the MD5 hash of a file, use the md5_file() function.

Syntax

Parameter Values

Technical Details

Return Value:	Returns the calculated MD5 hash on success, or FALSE on failure
PHP Version:	4+
Changelog:	The raw parameter became optional in PHP 5.0

More Examples

Example

$str = «Hello»;
echo «The string: «.$str.»
«;
echo «TRUE — Raw 16 character binary format: «.md5($str, TRUE).»
«;
echo «FALSE — 32 character hex number: «.md5($str).»
«;
?>

Example

Print the result of md5() and then test it:

if (md5($str) == «8b1a9953c4611296a827abf8c47804d7»)
echo «
Hello world!»;
exit;
>
?>

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Php md5 with key

md5 — Возвращает MD5-хеш строки

Не рекомендуется использовать эту функцию для обеспечения безопасности хранения паролей ввиду высокой скорости работы данного алгоритма. Более подробно читайте в разделе Ответы на часто задаваемые вопросы по хешированию паролей.

Описание

Вычисляет MD5-хеш строки string , используя » алгоритм MD5 RSA Data Security, Inc. и возвращает этот хеш.

Список параметров

Если необязательный аргумент binary имеет значение true , то возвращается бинарная строка из 16 символов.

Возвращаемые значения

Возвращает хеш в виде 32-символьного шестнадцатеричного числа.

Примеры

Пример #1 Пример использования md5()

if ( md5 ( $str ) === ‘1afa148eb41f2e7103f21410bf48346c’ ) echo «Вам зелёное или красное яблоко?» ;
>
?>

Смотрите также

• md5_file() — Возвращает MD5-хеш файла
• sha1_file() — Возвращает SHA1-хеш файла
• crc32() — Вычисляет полином CRC32 для строки
• sha1() — Возвращает SHA1-хеш строки
• hash() — Генерирует хеш-код (подпись сообщения)
• crypt() — Необратимое хеширование строки
• password_hash() — Создаёт хеш пароля

User Contributed Notes 7 notes

This comparison is true because both md5() hashes start ‘0e’ so PHP type juggling understands these strings to be scientific notation. By definition, zero raised to any power is zero.

Regarding Ray Paseur’s comment, the strings hash to:

The odds of getting a hash exactly matching the format /^0+e5+$/ are not high but are also not negligible.

It should be added as a general warning for all hash functions to always use the triple equals === for comparison.

Actually, the warning should be in the operators section when comparing string values! There are lots of warnings about string comparisons, but nothing specific about the format /^0+e5+$/.

If you want to hash a large amount of data you can use the hash_init/hash_update/hash_final functions.

This allows you to hash chunks/parts/incremental or whatever you like to call it.

I’ve found multiple sites suggesting the code:

Until recently, I hadn’t noticed any issues with this locally. but then I tried to hash a 700MB file, with a 2048MB memory limit and kept getting out of memory errors.

There appears to be a limit to how long a string the md5() function can handle, and the alternative function is likely more memory efficient anyway. I would highly recommend to all who need file hashing (for detecting duplicates, not security digests) use the md5_file() function and NOT the regular string md5() function!

Note, to those interested, as this was for a local application not a server, I was more concerned with results than memory efficiency. In a live environment, you would never want to read an entire file into memory at once when avoidable. (at the time of coding, I did not know of the alternative function)

From the documentation on Digest::MD5:
md5($data. )
This function will concatenate all arguments, calculate the MD5 digest of this «message», and return it in binary form.

md5_hex($data. )
Same as md5(), but will return the digest in hexadecimal form.

PHP’s function returns the digest in hexadecimal form, so my guess is that you’re using md5() instead of md5_hex(). I have verified that md5_hex() generates the same string as PHP’s md5() function.

(original comment snipped in various places)
>Hexidecimal hashes generated with Perl’s Digest::MD5 module WILL
>NOT equal hashes generated with php’s md5() function if the input
>text contains any non-alphanumeric characters.
>
>$phphash = md5(‘pa$$’);
>echo «php original hash from text: $phphash»;
>echo «md5 hash from perl: » . $myrow[‘password’];
>
>outputs:
>
>php original hash from text: 0aed5d740d7fab4201e885019a36eace
>hash from perl: c18c9c57cb3658a50de06491a70b75cd

function raw2hex ( $rawBinaryChars )
return = array_pop ( unpack ( ‘H*’ , $rawBinaryChars ));
>
?>

The complement of hey2raw.
You can use to convert from raw md5-format to human-readable format.

This can be usefull to check «Content-Md5» HTTP-Header.

$rawMd5 = base64_decode ( $_SERVER [ ‘HTTP_CONTENT_MD5’ ]);
$post_data = file_get_contents ( «php://input» );

if( raw2hex ( $rawMd5 ) == md5 ( $post_data )) // Post-Data is okay
else // Post-Data is currupted
?>

Note: Before you get some idea like using md5 with password as way to prevent others tampering with message, read pages «Length extension attack» and «Hash-based message authentication code» on wikipedia. In short, naive constructions can be dangerously insecure. Use hash_hmac if available or reimplement HMAC properly without shortcuts.

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How to Decrypt MD5 Passwords in PHP?

If you are new in the MD5 world, you probably ask yourself how to decrypt MD5 passwords in PHP after encrypting them.
In this post, I’ll show you how to do this, but you probably need an explanation about the MD5 algorithm before 🙂

The MD5 cryptographic algorithm is not reversible.
PHP can encrypt any word into MD5, but not decrypt an MD5 hash to retrieve the original word.
When using the MD5 algorithm to check passwords in PHP, we must have both side encrypted (the password typed and the password stored in the database).

I’ll remind you what is the MD5 algorithm and why you can’t reverse it to find the password.
Then I’ll show you how to validate the password in your code (with PHP samples).
And finally, I’ll show you how to use the MD5Online API to find lost passwords.

By the way, if you are interested in how MD5 decryption really works, I highly encourage you to take a look at my e-book “The Secrets of MD5 Decryption” here. It explains everything you need to know, going directly to the point with practical examples you can test on your computer. You don’t need any hardware to get started, just a few tips I give in this book.

What is MD5?

MD5 encryption

MD5 is an algorithm that generates a 32 characters string (hexadecimal) for any word or phrase given in input.
You can even encrypt an entire file into a MD5 hash.

MD5("MD5Online") = d49019c7a78cdaac54250ac56d0eda8a

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If you are interested in the encryption algorithm, you can check the Wikipedia page.
But for the moment you just have to remember that there is an infinite possibility of input for a finite output possibilities (always 32 characters).

So, the MD5 output is not unique, and you can’t reverse it.
But we’ll see in the next paragraph how the decryption works.

MD5 decryption

You must be saying, “If decryption is impossible, how does MD5Online work?”.

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• There is no decryption algorithm, the function md5_decrypt() doesn’t exist
• But every encryption process gives the same result

So, I now know that the MD5 hash corresponding to “MD5Online” is d49019c7a78cdaac54250ac56d0eda8a (previous part).
If someone asks me to decrypt this hash, I’m able to answer that there is a good chance that “MD5Online” is the encrypted word.

That is how the MD5 decryption tool is working on MD5Online.
We have a giant database of known MD5 hash, so we can find the result for a lot of hash.

The answer to your question is: no, it’s not really possible to decrypt MD5 passwords in PHP.
So, how can you validate user passwords if you can’t decrypt the database field?

How to validate MD5 passwords?

Theory

The MD5 algorithm is very fast.
So, you can use it where you want, without slowing down your website.

That’s why we were using MD5 to store passwords in a database.
And so to validate them, you can encrypt the input password, and check it with the database one.

The pseudo-code will look like this:

IF (MD5(INPUT_STRING) == DATABASE_PASSWORD) THEN LOGIN()

I’ll show you in the next paragraph how to manage the two steps with PHP.

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PHP/MySQL samples

Create a user account

The first step is to create a user account.
To do this, you need to create a database, with at least two fields: username and password.

For example, in MySQL, you can create something like this:

CREATE TABLE IF NOT EXISTS `users` ( `username` varchar(32) NOT NULL, `password` varchar(32) NOT NULL, PRIMARY KEY (`username`) )

The password will be MD5 encrypted, so it will always be 32 characters length.

To create a new user with PHP, you have to do something like that:

mysqli_query("INSERT INTO users (username, password) VALUES ('".$_POST['username']."','".md5($_POST['password'])."'"));

You probably already done that, you just need to use the md5() function to encrypt the password.
I recommend using salt with MD5, but it’s not mandatory to understand the process.

Obviously, before that, you need to connect to your MySQL database server, probably clean the $_POST data, and create a form in HTML to register the user.
But we are not here for a basic PHP lesson 🙂

Validate the user password

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Then come the part you didn’t know before reading this article.
In the login process, you need to compare the input password to the database password.

$query = mysqli_query("SELECT * FROM users WHERE username='".$_POST['username']."' AND password='".md5($_POST['password'])."'); if(mysqli_num_rows($query)) < //connect >else < //bad password >

So again, we’ll use the md5() function to encrypt the password before logging in the user.
We only check that the input password is the same as in the database.

At no time it is necessary to decrypt the password stored in the database.

How to finally decrypt passwords in PHP? (API)

If you still need to decrypt a high number of MD5 passwords for another reason that the one we have just seen, I have a solution for you.

MD5Online offer an API you can use in PHP (or with other languages) to send requests directly in our database
That way you can decrypt a lot of MD5 encrypted passwords automatically in PHP.

This is a paid service, if you are interested you will find more info on this page.

As soon as you have your VIP key, you can use this sample code:

 $md5 = I’ll let you adding a loop, and maybe a query to get all the passwords at once from your database.
But you have here the minimal part to use the MD5Online API in PHP.

Conclusion

That’s it, you now know how to decrypt MD5 passwords in PHP.
Or rather how to use them without decrypting them.

But I also give you a way to really decrypt them with the MD5Online API.
I hope you enjoy this article, feel free to share if it was helpful 🙂

Hi, my name is Patrick, I’m a web developer and network administrator. I have always been interested in security, and I created this website to share my findings with you.

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