SHA1, MD5, or SHA256: Which Hashing Algorithm Should I Use for PHP Logins?

SHA1, MD5, or SHA256: Which is Best for PHP Logins?

When implementing a PHP login system, choosing the optimal hashing algorithm is crucial for ensuring the security of stored passwords. This article will compare the three common options, SHA1, MD5, and SHA256, and recommend the most secure choice: bcrypt.

SHA1, MD5, and SHA256: Are There Security Differences?

None of these algorithms are inherently more secure than the others. They have been optimized for speed, making them susceptible to cracking using specialized hardware.

Using a Salt with SHA1/256

While using a salt is recommended, it is not enough to mitigate the weaknesses of SHA1 and SHA256. The attacker can still apply brute-force or rainbow table attacks on the salted hashes.

Secure Storage of Password Hashes

The provided function for creating a salt is inadequate. It uses a poorly designed MD5 function that is also susceptible to attack.

The Superior Choice: bcrypt

For modern PHP applications, bcrypt is the recommended option. It is a work factor based hashing algorithm that inherently incorporates salting and iterated hashing, making it highly resistant to cracking.

Implementing bcrypt in PHP 5.5

PHP 5.5 introduced built-in functions for password hashing, using bcrypt by default. Here's how to use them:

<code class="php">// Create a hash
$hash = password_hash($password, PASSWORD_DEFAULT, ['cost' => 12]);

// Verify the password
if (password_verify($password, $hash)) {
    // Success! Log the user in.
}</code>

For older versions of PHP, use password_compat to expose the API.

Caveats of bcrypt

• Truncates passwords longer than 72 characters.
• Truncates passwords containing NUL characters.

To address these caveats, consider using third-party libraries like ZendCrypt or PasswordLock.

TL;DR

Don't use SHA1, MD5, or SHA256 for PHP logins. Instead, opt for bcrypt for maximum security and resistance to cracking.

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