Can I Decrypt a Password Hash Generated by PHP\'s `password_hash` Function?

Decrypting Password Hashes in PHP Using Password_Hash

Question:

How do I decrypt a password hash generated using the PHP password_hash function? The password is stored in a database and needs to be compared to the entered user input.

Answer:

Unlike encryption, hashing is a one-way process. Once a password is hashed using password_hash, it cannot be decrypted back to its original value. Therefore, it is crucial to use password verification instead of decryption.

Password Verification using password_verify:

<code class="php">$hash = password_hash('examplepassword', PASSWORD_DEFAULT);
if (password_verify('examplepassword', $hash)) {
    echo 'Password is valid!';
} else {
    echo 'Invalid password.';
}</code>

In your login scenario, execute the SQL query using only the username:

<code class="php">$sql_script = 'SELECT * FROM USERS WHERE username=?';</code>

Then, compare the entered password to the stored hash in PHP:

<code class="php">if (password_verify($inputpassword, $fetchedPasswordHashFromDB)) {
   // Password matches
}</code>

Important Note:

Ensure you sanitize user input to prevent SQL injection attacks. Parameterize your queries using prepared statements or database abstraction layers.

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