How can I rehash my stored passwords which is stored in Database using md5?

Question

I have passwords stored in md5 hash. I want to rehash it using another hashing methods. How can I rehash it ?

I have tried to save the new hashed passwords in new field with new hashing methond eg SHA1

Answer 1

The usual approach is to check if user has new hash during the log-in. If she has — use it. If she doesn't — check via old hash and if there is a match then populate new field.

Also, please DO NOT USE md5 or sha1 or even sha256 for hashing passwords . Use password_hash() which is designed specifically for this use-case and provides way better security for your users.

This function is available starting with PHP 5.5, but there is a user-space implementation which works with older PHP versions